2017 Florida Beef Research Report

Transcription

1 2017 Florida Beef Research Report Department of Animal Sciences

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3 Table of Contents Genetics Impact of Hair Coat on Thermoregulation in Brangus Heifers...1 Fatty Acid Composition and Mineral Content Variation in Florida Crossbred Cattle... 5 Impact of Fetal Versus Maternal Contributions of Bos indicus and Bos taurus Genetics on Fetal Embryonic Development... 9 Genome Scan for Beef Tenderness in an Angus-Brahman Crossbred Population in Florida Meats Muscle Fiber Properties, Protein Degradation, and Tenderness of Angus-Brahman Multibreed Steers Nutrition Upcycling Bahiagrass Hay Using Cull Potatoes in an Ensiling System Comparison of Trace Mineral Source on Cow Trace Mineral Status, Reproduction, and Calf Weaning Weight on Two Commercial Ranches Effects of Prenatal and Postnatal Trace Mineral Supplement Source Provided to Gestating Angus and Brangus Cows over Two Production Cycles on Performance and Trace Mineral Status of Cows Effects of Prenatal and Postnatal Trace Mineral Supplement Source Provided to Gestating Angus and Brangus Cows over Two Production Cycles on Performance and Trace Mineral Status of Calves Effects of Prenatal and Postnatal Trace Mineral Supplement Source and Breed on Beef Calf Acute Phase Response to Weaning Effects of Prenatal and Postnatal Trace Mineral Supplement Source on Angus and Brangus Bull Growth, Performance, and Sexual Development Impact of Estrus Synchronization and Fixed-time Artificial Insemination on Calving Distribution in Bos indicus Influenced Beef Heifers Effects of Bismuth Subsalicylate and Calcium-Ammonium Nitrate on Liver Mineral Concentration and Performance of Growing Beef Heifers Supplementation of Cinnamaldehyde and Garlic Oil on Pre- and Post-weaning Growth Performance of Beef Cattle Fed Warm-season Forages... 91

4 Effect of Post-weaning Trace Mineral Source on Measures of Growth, Performance, and Sexual Development in Pre-pubertal Bos taurus Beef Bulls Evaluation of Brassica carinata as a Protein Supplement for Growing Beef Heifers Effects of Gradual Reduction in Frequency of Energy Supplementation on Growth and Immunity of Beef Steers Intake and Ruminal Fermentation Parameters of Beef Steers Consuming Bahiagrass Hay Treated with Calcium Oxide Effects of Timing of Vaccination Relative to Weaning and Post-weaning Supplementation Frequency on Growth and Immunity of Growing Beef Calves Reproduction The Effects of Biweekly Administration of Recombinant Bovine Somatotropin During the First Trimester on Fetal and Placental Development in Beef Heifers Pre-Weaning Injections of Bovine Somatotropin Enhanced Puberty Attainment and Calving Rates of Bos indicus-influenced Beef Heifers Administration of Recombinant Bovine Somatotropin Prior to Fixed-time Artificial Insemination and the Effects on Pregnancy Rates and Embryo Development in Beef Heifers Comparison of Two Alternate PGF2α Products in Two Estrus Synchronization Protocols in Beef Heifers Effects of Administration of Prostaglandin F2α 7 Days Prior to Initiation of the 7-Day CO-synch + CIDR Protocol in Beef Heifers on Estrus Response and Pregnancy Rates Forages Bahiagrass Performance Under Low Soil Nitrogen Annual and Perennial Peanut Mixed with Pensacola Bahiagrass in North Florida Warm-Season Grass-Legume Mixtures Options for North Florida Bermudagrass Varieties Testing in North Florida Limpograss Performance in North Florida The use of trade names in this publication is solely for the purpose of providing specific information. UF/IFAS does not guarantee or warranty the products named, and references to them in this publication does not signify our approval to the exclusion of other products of suitable composition.

5 Impact of Hair Coat on Thermoregulation in Brangus Heifers H. Hamblen 1, A. Zolini 1, M. Gobena 1, P. J. Hansen 1 and R. G. Mateescu 1 Synopsis Heat stress has detrimental impacts on the beef cattle industry in the state of Florida causing producers and researchers to work towards the development of selection strategies for thermoregulation. Hair coat significantly impacts vaginal body temperature in Brangus heifers and the high amount of variation in the temperatures suggest that a genetic component may be influencing thermoregulation. Summary Daily body temperatures at 5-min intervals over a 5-day period were recorded on approximately 725 Brangus two-year old heifers from the Seminole Tribe of Florida during summer Hair coat is one of the many factors we are examining. Length and thickness of hair varies considerably not only between breeds but also within breeds. This variation suggests that selection for a coat advantageous for improved thermotolerance in cattle is possible. A repeated measures model was used to investigate the effect of coat score on body temperature The coat was scored as excessively smooth (score 1, n = 526), fairly smooth (score 2, n = 189) or long coat (score 3, n = 7). The coat score had a significant effect on body temperature, where heifers with excessively smooth coat had lower body temperature throughout the 3 days of continuous body temperature measurements indicating that coat type plays an important role in the control of body temperature. Introduction High production levels in livestock are dependent on a good environment while unfavorable environments could lead to lower productivity by not allowing the true genetic potential of the animal to be expressed. Heat stress is a major cause of economic loss for beef cattle producers in tropical and subtropical environments. To cope with harsh environmental conditions, many producers have introduced Bos indicus breeds into their herds. While this has improved the heat adaptability in the crossbred animals, it also introduced other challenges. The hair type of an animal is one important factor influencing the ability of cattle to maintain a normal body temperature under extreme environmental conditions. Hair insulates the body by trapping air next to the skin, making heat exchange less efficient. More importantly, long and thick hair traps sweat, not allowing it to evaporate efficiently. Materials and Methods Data Collected on the ranch This experiment was conducted in August to September of 2016 with a total of 725 two-year old Brangus heifers at the Seminole Brighton Reservation in Okeechobee, Florida. The experiment was conducted over 4 weeks with approximately 200 heifers per week. Environmental variables were recorded. Temperature, humidity, and dewpoint temperature were measured using a HOBO U23 data logger. Additionally, two HOBO U22 data loggers recorded black globe temperature, with one being placed in the shade and the other in the sun at the location where the heifers were kept. All HOBO data loggers were programmed to take measurements every 15 minutes. Vaginal temperature was measured for five consecutive days by I-button data loggers attached to a blank CIDR. Each week, data loggers were placed in all heifers on Monday and removed on Friday. The I- buttons were programmed to record temperature every 5 minutes. Several parameters to describe animal s response were developed, such as minimum and maximum vaginal temperature, the difference between minimum and maximum vaginal temperature, and time between minimum and maximum vaginal temperature Florida Beef Research Report

6 Each heifer was assigned a coat score based on the length and thickness of their hair. Coat score classes are as follows: 1) excessively smooth; 2) fairly smooth; 3) long coat. A photograph was taken of each animal to later confirm coat scores. A repeated measures model was used to investigate the effect of the coat score and body temperature. Additionally, hair samples were taken from the top coat and under coat of each heifer to be used for length and diameter measurements. Results Preliminary data from this ongoing research trial are summarized in Table 1. There was a good level of variation in the temperature-humidity index (THI) over the time period evaluated, ranging from a minimum of 73 to a maximum of 89. Previous studies suggest that 72 to 79 THI corresponds to mild level of heat stress, 80 to 89 THI represents moderate level of heat stress, and a THI greater than 90 is indicative of severe heat stress. There was also a high level of variation in the vaginal temperature (Figure 1), which ranged overall from 36.6 C to 42.3 C. Most importantly, the variation in the maximum vaginal temperature between 38.8 C and 42.3 C is suggesting that genetic variants controlling body temperature are segregating in Brangus cattle. All heifers were managed on the same environment; therefore, the variation in vaginal temperature was not an effect of the environment. The coat was scored as excessively smooth (score 1, n = 526), fairly smooth (score 2, n = 189) or long coat (score 3, n= 7). The fairly smooth and long coat classes were combined into one due to the small number of long coat scores. The coat score had a significant effect on body temperature, where cows with excessively smooth coat had lower body temperatures throughout the 3 days of continuous body temperature measurements (Figure 2) indicating that coat type plays an important role in the control of body temperature. A slick dense coat provides a greater resistance to heat transfer to the skin and therefore reduces the heat gain from the environment when the animals is in sunlight. Differences in coat score significantly affected body temperature on the hottest day of the study. On average, animals with an excessively smooth coat score regulated their body temperature and kept themselves cooler than those with a coat score of fairly smooth. Conclusion Beef cattle producers in tropical and subtropical climates, such as Florida, feel the burden of economic losses caused by heat stress. Although producers have greatly improved the heat tolerance of their herds by introducing Bos indicus genetics, there is still room for improvement. The preliminary analysis of the data we have collected so far leads us to believe that there is a genetic component to thermotolerance. The goal of this study is to develop the genomic tools that can be implemented in selection programs in order to increase thermotolerance while still maintaining high production traits. Acknowledgements Financial support was provided by the Florida Agricultural Experiment Station Hatch Project number FLA-ANS , The Seminole Tribe of Florida, and the International Brangus Breeders Association Florida Beef Research Report

7 Table 1. Summary statistics including mean, standard deviation, minimum, and maximum values of 725 two-year old Brangus heifers exposed to heat stress during summer Variable 1 Mean Std Dev Minimum Maximum Minimum vaginal temp, C Maximum vaginal temp, C Minimum THI Maximum THI Max-Min vaginal temp, C Minimum and maximum vaginal temperature during 3 consecutive days, minimum and maximum temperature-humidity index (THI) during the same 3 consecutive days, and the difference between the minimum and maximum vaginal temperature for each heifer. Figure 1. High (red), average (blue), and low (green) vaginal temperatures over a 3 day period Florida Beef Research Report

8 Figure 2. Relationship of vaginal temperature and coat score during a 24-h period. Excessively smooth = coat score 1, fairly smooth = coat score 2 and 3. Figure 3. Relationship of coat score and vaginal temperature between coat scores and within coat scores over a 3 day period. Excessively smooth = coat score 1, fairly smooth = coat score Florida Beef Research Report

9 Fatty Acid Composition and Mineral Content Variation in Florida Crossbred Cattle S. Flowers 1, H. Hamblen 1, and R. G. Mateescu 1 Synopsis This study analyzed the fatty acid composition and mineral content variation in beef from Florida crossbred cattle and determined the relationship of these beef nutritional attributes with breed type. Summary Carcass data and steak samples were collected from 230 head of cattle. The breed type of the population ranged from 100% Angus to 100% Brahman. All 230 samples were analyzed for fatty acid composition and 150 were tested for mineral content. There is a correlation between the fatty acid content and breed type. A wide range of variation was found in terms of mineral content, specifically iron, which implies there is opportunity for selection of cattle with a desirable phenotype: in this case the desirable phenotype is beef of higher mineral content. Introduction Seven factors have been identified as consequential for driving beef demand. Ranked in the order of their relevance to consumers these factors are: price, food safety, product quality, health, nutrition, social aspects, and sustainability. Since Florida beef producers cannot control price, they should focus on the safety, quality, healthfulness, and nutritional value of beef products to best meet the desires of the consumer. One of the greatest selling points of beef is that it provides a superior eating experience/taste over other protein sources. Over and above this eating experience, beef is a nutrient rich foodstuff. However, it also is considered to have an unhealthful fatty acid composition. Nutrient profiles are not uniform across cattle, and variations in fatty acid composition and mineral content is partially attributable to genetic factors. If beef producers could select cattle that have more healthy fatty acid profiles or higher iron and zinc content, they could enhance the nutritional and health value of beef. Beef perceived as more healthy could increase profit to producers because consumers may likely be willing to pay a premium for beef that consistently has an improved nutritional and health value. In addition, this nutritionally-enhanced beef could increase overall demand for beef and lead to continued growth of the beef industry. The goal of this study was to characterize the amount of natural variation in fatty acid and mineral content and determine the relationship between the nutritional and healthfulness value and breed composition. Materials and Methods Population and phenotypic data collection The cattle in this study are part of the University of Florida multibreed herd of cattle that range from 100% Angus to 100% Brahman. All cattle in this study have full pedigree records defining their exact breed composition. Cattle were classified into six different groups based on their expected Angus and Brahman breed composition. Based on the Angus composition, the grouping was as follows: 1 = 100 to 80%; 2 = 79-65%; 3 = 62.5% (Brangus); 4 = 59 to 40%; 5 = 39 to 20%; 6 = 19 to 0%..Steers were fed a high-grain diet to reach a predetermined finishing end-point. When steers reached 0.5 inch of backfat over the ribeye, they were transported to a commercial packing plant and harvested using established USDA- FSIS procedures. A 1-inch steak removed from the 12th/13th rib was sampled per animal from the Longissimus dorsi muscle interface. Steaks were transported to the Meat Science laboratory of the Department of Animal Sciences at University of Florida, vacuum packaged, aged for 14 d from the harvest date at 36 F and frozen at -4 F. A thin shaving of each steak trimmed of external fat and Florida Beef Research Report

10 connective tissue, was powdered, and analyzed at Iowa State University for fatty acid and mineral composition. Statistical Analysis Fatty acid composition was calculated on a percentage basis by using the peak areas. All fatty acid components were used to calculate total percentage of saturated fatty acids (SFA), monounsaturated fatty acids (MUFA), polyunsaturated fatty acids (PUFA), omega-3 PUFA, and omega-6 PUFA. Additionally, the atherogenic index was calculated as described by Ulbricht and Southgate (1991) by using the ratio of palmitic and myristic acids to total unsaturated fatty acid. All statistical analyses were performed using SAS (SAS Inst. Inc., Cary, NC). The MEANS procedure was used to produce descriptive statistics for fatty acid and mineral composition data. Least squares means estimating the effect of breed were obtained from the PROC GLM procedure of SAS using a fixed effects model which had breed and birth year. Least squares means were separated using the PDIFF option of GLM in SAS. Results Saturated fatty acids are known to have a negative effect on human health, while polyunsaturated fatty acids are known to have a positive effect. There was no significant difference (P>0.05) in the amount of MUFA among the different breed groups (ranging for 44.2% to 45.8%). However, a beneficial trend was found in both the SFA and PUFA, with SFA declining from 51.3% to 47.5% and the PUFA increasing from 4.3% to 6.9% as the percentage of Brahman increased from 0 to 100%, as shown in Figure 1. The mean iron concentration in Bos indicus influenced cattle was µg/g muscle. However, there was variation in iron concentration; in beef from Bos indicus influenced cattle, as shown in Figure 2. The maximum iron concentration in this study was µg/g muscle; which represents between 15 and 34% of the recommended daily allowance for iron depending on gender and age. The variation in iron content provides an opportunity for genetic selection of cattle with a superior phenotype, or nutritional value. Conclusion Genomic selection provides an opportunity to change nutritive value and healthfulness of Florida beef in a desirable direction with substantial positive consequences for human health and wellbeing. We anticipate that genomic tools for implementing genetic marker-assisted selection will soon be available and will open up opportunities for the breeding of Florida beef with improved nutritional and healthfulness value. Additionally, we anticipate consumers will be willing to pay a premium for more nutritious and healthier beef. Future work will clarify how large these economic returns may be and how the premium would impact Florida beef producers. Acknowledgements Financial support provided by Florida Agricultural Experiment Station Hatch Project number FLA-ANS and the Florida Beef Council Florida Beef Research Report

11 Mean SFA (% of total FA) 52% 51% 51% 50% 50% 49% 49% 48% 48% 47% 100%A 75%A Brangus 50%A 25%A 100%B 8% 7% 6% 5% 4% 3% Mean PUFA (% of total FA) Figure 1. Effect of breed type on saturated fatty acids (SFA) vs polyunsaturated fatty acids (PUFA) as a proportion of total fatty acid (FA) in cattle harvested after finishing on a high-grain diet. Angus = A, Brahman = B. Number of animals Iron concentration in Brahman influenced cattle Iron concentration (µg iron/g muscle) Figure 2. Distribution of iron concentration in Brahman-influenced cattle harvested after finishing on a high-grain diet Florida Beef Research Report

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13 Impact of Fetal Versus Maternal Contributions of Bos Indicus and Bos Taurus Genetics on Fetal Embryonic Development P. L. P. Fontes 1, D. D. Henry 1, F. M. Ciriaco 1, N. Oosthuizen 1, L. B. Canal 1, C. D. Sanford 1, V. R. G. Mercadante 2, A. D. Ealy 2, S. E. Johnson 2, N. DiLorenzo 1 and G. C. Lamb 3 Synopsis Bos taurus recipients and embryos experienced greater pregnancy failure when exposed to nutrient restriction. In addition, Bos indicus fetuses were smaller than Bos taurus fetuses, and resulted in greater recipient circulating concentrations of pregnancy associated glycoproteins. Summary The aim of this study was to evaluate the impact of energy restriction on embryonic survival in Bos taurus and Bos indicus genotypes, as well as the influence of maternal and fetal systems on early fetal development. The experiment used a reciprocal embryo transfer approach in a completely randomized design with a factorial arrangement of treatments. Embryo recipient cows were assigned to 1) a diet to meet daily maintenance requirements (MAINT), or 2) a diet that restricted intake of nutrients to 70% of energy maintenance requirements (RESTR). Angus (AN) and Brangus (BN) female embryos were produced and randomly transferred to either AN or BN recipients fed the respective diets for 28 d to create the following treatment combinations (AN AN RESTR, n =14; AN AN MAINT, n = 19; AN BN RESTR, n = 16; AN BN MAINT, n = 17; BN BN RESTR, n = 15; BN BN MAINT, n = 19; BN AN RESTR, n = 14, BN AN MAINT, n = 19). Recipients remained on the dietary scheme until d 91. Pregnancy diagnosis was assessed at d 28 of gestation and fetal morphometries from d 42 to 91. Plasma pregnancy specific protein B (PSPB) was assessed weekly from d 28 to 91. Recipient body weight (BW) and BCS were significantly impacted by the dietary treatments (P<0.05). In addition, AN RESTR recipients had greater (P<0.05) pregnancy failure at d 28 than AN MAINT and BN in both diets. Furthermore, RESTR recipients that received an AN embryo experienced greater (P< 0.05) pregnancy failure than AN embryos transferred to MAINT recipients. Angus embryos resulted in lesser (P<0.05) plasma PSPB concentration, but greater (P<0.05) fetal length when compared to BN embryos. These results indicate that Bos taurus cattle may be more susceptible to embryonic loss than Bos indicus when submitted to a feed restriction scheme during the first trimester of gestation, and that differences in growth rate and PSPB production exists between the two subspecies. Introduction Breeds generated from crossing Bos indicus Bos taurus cattle breeds contain greater tolerance to elevated ambient temperatures and humidity than most Bos taurus beef breeds (Hansen, 2004). It is estimated that approximately 30% of cattle in the U.S. contain some Bos indicus genetics. In addition, 40% of beef cows and 50% of the country s cow-calf producers are located in the southern U.S. where Bos indicus cattle and their crosses are located. It, therefore, is paramount that we learn more about the biology of Bos indicus cattle so that this new knowledge can be used to modify management systems for optimal production efficiency. Both historical literature and recent findings from our laboratory demonstrate that Bos indicus fetuses grow at a slower rate in utero during early and mid-gestation (Mercadante et al., 2013, Ferrell, 1991; O'Rourke et al., 1991). Moreover, there are indications that Bos indicus fetuses undergo compensatory growth in late gestation to generate fetuses that can be larger than their Bos taurus counterparts at birth (Mercadante et al., 2013). Subspecies genotype also affects plasma pregnancy-associated glycoproteins (PAG) concentrations in early pregnancy, where Brangus cows have greater PAG concentrations than 1 North Florida Research and Education Center, University of Florida, Marianna, FL 2 Department of Animal & Poultry Sciences, Virginia Tech, Blacksburg, VA 3 Department of Animal Science, Texas A&M University, College Station, TX Florida Beef Research Report

14 Angus (Mercadante et al., 2013). Nutrient utilization and feed efficiency are also thought to be different between Bos indicus and Bos taurus animals (Elzo et al., 2009). Therefore, the objective of this study was to determine how maternal and fetal systems influence early fetal development in Bos indicus and Bos taurus cattle. We hypothesize that early fetal and placental development is modified by inclusion of Bos indicus genetics into the maternal genotype. In addition, we hypothesize that dietary restriction in early pregnancy will limit fetal development in both Bos indicus and Bos taurus cows, but the magnitude of the comprised development will be less evident in Bos indicus cattle. Materials and Methods A reciprocal embryo transfer (ET) approach was used in a completely randomized design with a factorial arrangement of treatments in order to generate 55 pregnancies over two consecutive years (n = 55). Recipient cows (n = 134) were randomly assigned to 1 of the 2 dietary treatments: 1) a diet to meet 100% daily maintenance requirements (MAINT), or 2) restricted intake of nutrients to 70% of energy maintenance requirements (RESTR). Angus (AN) and Brangus (BN) embryo donors were superovulated and artificially inseminated (AI) with female sexed-sorted semen from the same breed. Embryos were then collected and randomly transferred to either AN or BN recipients fed the respective diets; therefore generating 8 treatment combinations (AN AN RESTR, n =15; AN AN MAINT, n = 19; AN BN RESTR, n = 16; AN BN MAINT, n = 17; BN BN RESTR, n = 15; BN BN MAINT, n = 19; BN AN RESTR, n = 14, BN AN MAINT, n = 19). Female sex-sorted semen from 4 AN and 2 BN sires was utilized to AI donor cows. In addition, the generated embryos were not only assigned to recipients in order to equally generate the previously described treatment combinations, but also to equally distribute the effects of sire, donor cow, and embryo grade score (Bo and Maplesoft, 2013) between the different recipient breeds, dietary treatment, and parity (primiparous or multiparous). Angus and BN cows were randomly assigned to 1 of 2 dietary treatments 28 d prior to embryo transfer (d- 21): 1) diet formulated to meet the daily requirements of a 1213 lb of BW beef cow (NRC, 2000), comprised of 60 % fiber pallets, 30%, soybean hulls, 5 % bermudagrass (Cynodon dactylon), and 5 % peanut hulls (CP = 12.5%, TDN = 46 %; MAINT); and 2) diet formulated to meet 70% of daily requirements, comprised of 70 % fiber pallets, 10 % soybean hulls, 5 % bermudagrass (Cynodon dactylon) hay, and 15 % peanut hulls (CP = 11.2 %, TDN = 37 %; REST). Recipient cows remained on the described feeding scheme until d 91 (91 d of gestation), then all cows were submitted to a diet to meet 100% of the maintenance requirements for the remaining of gestation. Diagnosis of pregnancy was assessed by transrectal ultrasonography on d 28 with an Ibex ultrasound equipped with a linear 5 MHz multifrequency transducer. A ultrasound video was recorded at d 42, 49, 56, 63, 70, 77, 84 and 91 and in a frame-by-frame fashion, the ideal position and orientation of the conceptus was chosen to measure embryo length (CRL) as previously described (Riding et al., 2008). The BioPRYN Quantitative pregnancy-specific protein B (PSPB) ELISA (BioTracking Inc., Moscow, ID) was used to quantify circulating pregnancy-associated glycoprotein (PAG) concentrations in plasma harvested from blood collected at d 28, 35, 42, 49, 56, 63, 70, 77, 84, and 91 of pregnancy. This assay was developed to recognize PSPB (also known as PAG1), but it also detects other PAGs in circulation (Sasser et al. 1986, Xie et al. 1997). Intra-assay coefficients of variation averaged 2.78% and 1.60% for the two controls. Inter-assay coefficients of variation were 3.89% and 4.09% for the same two controls, respectively. All data were analyzed using the SAS statistical package (SAS Inst. Inc., Cary, NC; Version 9.4). The present study was a completely randomized design with a 2 x 2 x 2 factorial arrangement of treatments, where recipient breed (AN and BN), embryo breed (AN and BN) and recipient diet (MAINT and REST) represented the 3 different levels of factorials. Recipient cow s individual intake of nutrients were obtained during the experiment, therefore cow was considered the experimental unit. Continuous variables were analyzed by the MIXED procedure and categorical variables were analyzed using the Florida Beef Research Report

15 GLIMMIX procedure. For a more conservative interpretation of the data, the Tuckey s method was used for all simultaneous pairwise comparisons. P-values 0.05 were considered significant, and no tendencies will be discussed throughout this report. Results The dietary approach used in this experiment successfully induced an energy restriction scenario, as shown by the different percentage of energy requirements met by the diets (MAINT = 107.3% and REST = 81.4%), along with the significant impact of diet in recipient BW (P = 0.02) and BCS loss from d-21 to d 91(P = 0.02; Table 1). When weekly repeated measurements of BW and BCS were evaluated, a diet day interaction was observed for both recipient BW (P<0.01; Figure 1) and BCS (P<0.01; Figure 2), where recipients in the REST diet had lower BW on d 28, 35, 56, 70, 77 and 84 (P<0.05), together with lower BCS at d 56, 63, 70, 77, 84 and 91 (P<0.05). A recipient breed diet interaction was observed on pregnancy failure by d 28 of gestation (P<0.01), where AN cows submitted to the REST diet had increased pregnancy failure compared to AN in the MAINT diet and BN cows in both REST and MAINT diets (Figure 3). In addition, there was an embryo breed diet interaction (P = 0.01) on pregnancy failure at d 28. Recipients in the REST diet that received an AN embryo experienced greater pregnancy loss than recipients in the REST diet receiving BN embryos, regardless of the recipient breed (Figure 4). Embryos that were transferred to AN recipients had greater CRL at d 91 of gestation when compared to embryos carried by BN recipients (recipient breed day: P<0.01; Figure 5), regardless of the embryo breed. Furthermore, recipients that received BN embryos had greater plasma concentrations of PSPB at d 91 when compared to recipients that received AN embryos (embryo breed day: P<0.01; Figure 6), regardless of the recipient breed. Acknowledgements The authors would like to thank Zoetis Animal Health (Parsippany, NJ) for their donation of PGF 2α (Lutalyse), GnRH (Factrel), and CIDR inserts (EAZI-BREED CIDR). Sincere appreciation is also expressed to P. Folsom, M. Foran, O. Helms, D. Jones, C. Nowell, T. Schulmeister, and D. Thomas for their assistance with data collection and laboratory analysis. Furthermore, the authors would like to acknowledge the USDA for providing funding for this experiment. Literature Cited Bo and Maplesoft Anim. Reprod., 10: Elzo, M. A. et al., J. Anim. Sci. 90: Ferrell, C. L J. Anim. Sci. 69: Hansen, P.J Anim. Reprod. Sci. 83: Mercadante et al., : O Rourke P. K. et al., Theriogenology 36: Florida Beef Research Report

16 Table 1. Effects of dietary treatments 1 on recipient BW and BCS. Item REST MAINT SEM P-value Initial BW, lb BW at d 28, lb BW change d-21 to 28, lb BW change d-21 to 91, lb Initial BCS BCS change d-21 to < MAINT: diet formulated to meet the daily requirements of a 1213 lb of BW suckled beef cow (NRC, 2000), comprised of 60 % fiber pallets, 30%, soybean hulls, 5% bermudagrass (Cynodon dactylon) hay, and 5% peanut hulls (CP = 12.5%, TDN = 46%) and REST: diet formulated to meet 70% of daily requirements, comprised of 70% fiber pallets, 10% soybean hulls, 5% bermudagrass (Cynodon dactylon) hay, and 15% peanut hulls (CP = 11.2%, TDN = 37%;). Diet effect: P<0.01; Day effect: P<0.01; Diet Day: P< Body weight, lb MAINT REST Day of gestation Figure 1. Effects of dietary scheme on recipient BW; MAINT: Diet formulated to meet the daily requirements of a 1213 lb of BW suckled beef cow (NRC, 2000), comprised of 60 % fiber pallets, 30%, soybean hulls, 5% bermudagrass (Cynodon dactylon) hay, and 5% peanut hulls (CP = 12.5%, TDN = 46%) and REST: Diet formulated to meet 70% of daily requirements, comprised of 70% fiber pallets, 10% soybean hulls, 5% bermudagrass (Cynodon dactylon) hay, and 15% peanut hulls (CP = 11.2%, TDN = 37%;). Diet effect: P<0.01; Day effect: P<0.01; Diet Day: P< Florida Beef Research Report

17 6 Body condition score 5 4 * * * * * * 3 MAINT REST Day of gestation Figure 2. Effects of dietary scheme on recipient BCS; MAINT: Diet formulated to meet the daily requirements of a 1213 lb of BW suckled beef cow (NRC, 2000), comprised of 60 % fiber pallets, 30%, soybean hulls, 5% bermudagrass (Cynodon dactylon) hay, and 5% peanut hulls (CP = 12.5%, TDN = 46%) and REST: Diet formulated to meet 70% of daily requirements, comprised of 70% fiber pallets, 10% soybean hulls, 5% bermudagrass (Cynodon dactylon) hay, and 15% peanut hulls (CP = 11.2%, TDN = 37%;). Diet effect: P<0.01; Day effect: P<0.01; Diet Day: P< Florida Beef Research Report

18 100 Pregnancy failure, % a b 75.4 a a MAINT REST AN BN 18.7 Recipient breed Figure 3. Effects of recipient embryo breed on pregnancy failure at d 28 of gestation. MAINT: Diet formulated to meet the daily requirements of a 550 kg of BW suckled beef cow (NRC, 2000), comprised of 60 % fiber pallets, 30%, soybean hulls, 5% bermudagrass (Cynodon dactylon) hay, and 5% peanut hulls (CP = 12.5%, TDN = 46%) and REST: Diet formulated to meet 70% of daily requirements, comprised of 70% fiber pallets, 10% soybean hulls, 5% bermudagrass (Cynodon dactylon) hay, and 15% peanut hulls (CP = 11.2%, TDN = 37%;). Recipient breed diet interaction: P<0.01. a, b Means without a common letter within bar differ (P<0.05) Florida Beef Research Report

19 MAINT REST Pregnancy failure, % AN BN Embryo breed Figure 4. Effects of embryo breed and diet on pregnancy failure at d 28 of gestation. MAINT: Diet formulated to meet the daily requirements of a 550 kg of BW suckled beef cow (NRC, 2000), comprised of 60 % fiber pallets, 30%, soybean hulls, 5% bermudagrass (Cynodon dactylon) hay, and 5% peanut hulls (CP = 12.5%, TDN = 46%) and REST: Diet formulated to meet 70% of daily requirements, comprised of 70% fiber pallets, 10% soybean hulls, 5% bermudagrass (Cynodon dactylon) hay, and 15% peanut hulls (CP = 11.2%, TDN = 37%;). Recipient breed diet interaction: P<0.01. a, b Means without a common letter within bar differ (P<0.05) Florida Beef Research Report

20 * Crown to rump length, mm AN BN Day of gestation Figure 5. Effects of recipient breed on fetal crown to rump length (CRL). Transrectal ultrasonography was performed weekly from d 42 to d 91, and fetal CRL was assessed. At d 63, 70, 77, 84 and 91, crown to nose length (CNL) was used to estimate CRL as previously described (Riding et al., 2008). AN: Angus recipient and BN: Brangus recipient. *Recipient breed Day interaction: P< Florida Beef Research Report

21 Plasma concentration of PSPB, ng/ml * AN BN Day of gestation Figure 6. Effects of embryo breed on recipient s plasma concentration of PSPB. Blood samples were collected weekly from d 28 to 91. AN: recipients that received an Angus embryo. BN: Recipients that received a Brangus embryo. Embryo breed day interaction: * P< Florida Beef Research Report

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23 Genome Scan for Beef Tenderness in an Angus-Brahman Crossbred Population in Florida J.D. Leal-Gutíerrez 1, M.A. Elzo 1, D. Johnson 1 and R.G. Mateescu 1 Synopsis Potential chromosomal regions containing 22 genes could explain phenotypic variation in traits related to tenderness in Angus-Brahman steers. Summary Consumers develop perceptions that will directly contribute to subsequent market demand for beef; however, inconsistencies in meat tenderness have been widely reported. Genetic markers have been used as the most suitable strategy to uncover genomic regions able to explain the phenotypic variability present in meat quality. One steak from the longissimus dorsi muscle of 673 steers was used to determine tenderness by Warner-Bratzler shear force and 496 steaks were used in a trained sensory panel to assess tenderness and connective tissue amount. A total number of 22 genes were determine as potential chromosomal regions able to explain phenotypic variation in traits related to tenderness in the present population. Introduction Meat quality is determined by multiple factors, including tenderness, water-holding capacity, color, nutritional value and safety, and importance of these traits varies depending on both the type of product and the consumer profile (Koohmaraie & Geesink, 2006). Tenderness has been established as the most important quality trait in beef, and it depends on the amount of connective tissue, myofibrillar protein degradation (Houbak, et al., 2008) and intramuscular fat content. In a few seconds, a consumer develops perceptions that will directly contribute to subsequent market demand for beef (Harper, 1999), but a big problem of inconsistent meat tenderness has been reported, and this inconsistency must be a top priority of the beef cattle industry (Mohammad Koohmaraie, 1996). This requires a greater understanding of the processes that affect meat tenderness and the adoption of such information by the beef cattle industry (Mohammad Koohmaraie, 1996). The assessment of meat quality by trained panels or even physical measures is costly, and direct selection on sensory tests is not feasible (Renand, et al., 2001). Accordingly, it is important to find biological components related to sensory attributes which are easy to measure and sufficiently heritable to be selected for (Renand et al., 2001), because the consumer dissatisfaction will be addressed only when the problem of unacceptable variation in meat tenderness is solved (Mohammad Koohmaraie, 1996). Genetic markers such as single nucleotide polymorphisms (SNPs) have been used as the most suitable strategy to uncover genomic regions able to explain the phenotypic variability in traits like meat quality. The objective of this study was to perform a whole genome scan (WGS) to find genes and genomic regions associated with meat quality traits related to beef tenderness. Materials and Methods Population and phenotypic data Animals used in the study belong to the multibreed Angus-Brahman herd from University of Florida (Elzo et al., 2012) born between 2007 and This population has animals with different percentages of Angus-Brahman blood. When steers reached 0.5 in over the ribeye, they were transported to a commercial packing plant and harvested. The average slaughter weight was 1186 ± 721 lb at 17 ± 1.2 months. Two 1.0 in steaks from the longissimus dorsi muscle at the 12th/13th rib interface were sampled from each animal, transported to the Meat Science laboratory at University of Florida, aged for 14 d at 1-4 C, and then stored at 20 C. Thawed steaks were cooked to an internal temperature of 71 C in an openhearth grill. Objective tenderness was measured by Warner-Bratzler Shear Force (WBSF) on 673 steaks, Florida Beef Research Report

24 and sensory tenderness (TEND) and sensory connective tissue amount (CT) were measured through a trained sensory panel on 496 steaks. Genome-wide association analysis Genomic DNA was extracted from blood using the DNeasy Blood & Tissue kit (Qiagen, Valencia, California) and stored at 20 C. Animals were genotyped with the Bovine GGP F250 array (GeneSeek, Inc., Lincoln, NE, USA) which contains approximately 250,000 SNPs or genetic markers. Data processing and analysis were performed using the Genetics Q-K analysis workflow of JMP-Genomics 6.0 software (SAS Institute). Only animals with a calling rate higher that 85%, and autosomal markers with minor allele frequency higher that 5% were included in the analysis. The mixed model K method including the genomic relationship matrix and fixed effects SNP and birth year was applied (Stich et al., 2008; Stich & Melchinger, 2009; Yu et al., 2006). The genome wide significance threshold was equal to Results The means and standard deviations for WBSF, TEND and CT in this population were 9.48 ± 3.31 lb, 5.5±0.84 and 6.1±0.82, respectively. Out of 221,077 SNPs, 115,287 were included in the WGS analysis. Figure 1 shows the six significant SNPs identified by the WGS for TEND. Figure 2 presents the association results for the WGS for CT and Figure 3 the association results for the WGS for WBSF. Thirteen SNPs were associated with CT and seven with WBSF. Table 1 reports the chromosomal location of the associated SNPs by trait. In the present population 22 genes were identified as potential chromosomal regions able to explain phenotypic variation in traits related to tenderness, and 32% of these genes have been reported as involved in gene expression, 27% play a role in cell differentiation and 9% in apoptosis (Table 1). Further research is necessary in order to be able to identify the causative polymorphisms located in the chromosomal regions mapped in the present population. Literature Cited Harper Aust J Agr Res, 50, Houbak et al Meat Sci, 79(1), Koohmaraie Meat Sci, 43(SUPPL. 1), Koohmaraie and Geesink Meat Sci, 74, Renand et al Meat Sci, 59, Stich and Melchinger BMC Genomics, 10(1), 94. Stich et al Genetics, 178(3), Yu et al Nat Genet, 38(2), Acknowledgements Financial support provided by Florida Agricultural Experiment Station Hatch Project number FLA-ANS , Florida Beef Council, and Florida Cattlemen s Association Beef Enhancement Fund Award Florida Beef Research Report

25 Table 1. Genomic location of the significant SNPs for connective tissue, (CT), sensory tenderness (TEND) and Warner-Bratzler Shear Force (WBSF) in longissimus dorsi muscle in an Angus-Brahman crossbred population Trait SNP name Allele s Chr.$ Position SNP locatio n* Gene+ Gene name Cellular pathway# A B C D E POU class 6 CT rs T_C Genic POU6F2 homeobox Interge CT BTB_ A_G CT rs G_A Genic SSC5D Interge CT rs C_T neic RPS9 CT rs G_A Genic CNOT3 CT rs C_G Genic OSCAR CT rs C_T Genic NLRP5 CT CT neic NFIB Nuclear factor I B + Scavenger receptor cysteine rich family member with 5 domains + Ribosomal protein S9 + CCR4-NOT transcription complex subunit 3 + Osteoclast associated, immunoglobulinlike receptor + + NLR family pyrin domain containing 5 + BovineHD A_G Interge neic SLC47A1 Solute carrier family 47 member 1 + BovineHD T_G Genic ATRNL1 Attractin like 1 + ARS_BFGL_N GS_ A_G Interge BCL2 interacting CT neic BNIP3 protein 3 + UA_IFASA_75 Interge CREB/ATF bzip CT 12 A_C neic CREBZF transcription factor + Interge CT rs C_T neic LGALS12 Galectin 12 + EH-domain CT rs G_A Genic EHD1 containing 1 + Cilia and flagella associated protein TEND rs G_A Genic CFAP TEND rs G_A Genic CFAP54 TEND rs A_G Genic GPR98 TEND rs T_C Genic GPR98 TEND rs A_G Genic GPR98 Cilia and flagella associated protein 54 + Adhesion G protein-coupled receptor V1 + Adhesion G protein-coupled receptor V1 + Adhesion G protein-coupled receptor V Florida Beef Research Report

26 TEND BovineHD A_G Interge neic SLC47A1 WBSF rs A_C Genic NUMBL BovineHD1900 WBSF T_C Genic BLMH Solute carrier family 47 member 1 + Terminal uridylyl transferase 1, U6 snrna-specific + TEND rs A_C Genic TUT1 BovineHD1800 Interge WBSF A_G neic IFNL1 Interferon lambda 1 + NUMB like, endocytic adaptor protein + WBSF rs C_T Genic SMG6 Interge WBSF rs C_T neic RWDD4A Interge WBSF rs A_G neic RWDD4A ARS_BFGL_N GS_ WBSF T_C Genic LRP5 Bleomycin hydrolase + SMG6, nonsense mediated mrna decay factor + RWD domain containing 4 + RWD domain containing 4 + LDL receptor related protein 5 + $Chromosome number *Location of the SNP relative to the gene (genic = inside the gene, intergenic = outside the gene). +The gene where the SNP is located or the closest gene for SNPs located outside a gene. #The cellular pathways involving the genes: A = Gene-expression; B= Cell-differentiation; C= Cell-signaling; D= Apoptosis; E= other pathway Florida Beef Research Report

27 Figure 1. Plot of the genome-scan results for connective tissue in longissimus dorsi muscle in an Angus- Brahman crossbred population. Each dot corresponds to a SNP having its chromosomal location in the X axis and its significance level in the Y axis. The red line represents the genome wide significance threshold (any SNP above this line has a significant effect on the trait) Florida Beef Research Report

28 Figure 2. Plot of the genome-scan results for sensory tenderness in longissimus dorsi muscle in an Angus-Brahman crossbred population. Each dot corresponds to a SNP having its chromosomal location in the X axis and its significance level in the Y axis. The red line determine the genome wide significance threshold (any SNP above this line has a significant effect on the trait) Florida Beef Research Report

29 Figure 3. Plot of the genome-scan results for Warner-Bratzler shear force (WBSF) in longissimus dorsi muscle in an Angus-Brahman crossbred population. Each dot corresponds to a SNP having its chromosomal location in the X axis and its significance level in the Y axis. The red line determine the genome wide significance threshold (any SNP above this line has a significant effect on the trait) Florida Beef Research Report

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31 Muscle Fiber Properties, Protein Degradation, and Tenderness of Angus- Brahman Multibreed Steers T. Scheffler 1, P. Ramos 1, D. Johnson 1, J. Scheffler 1, M. Elzo 1, R. Mateescu 1, A. Bass 1, C. Carr 1, and S. Wright 1 Synopsis Muscle characteristics and protein degradation were evaluated in steers varying in Brahman composition. Delayed postmortem proteolysis stunts tenderization of Brahman beef, which may be related to mitochondrial parameters that prevent calcium-mediated activation of proteases involved in beef tenderization. Summary Inconsistent tenderness is a major obstacle to improving the value of Brahman-influenced calves and enhancing the overall quality of the beef supply. Greater toughness of Brahman beef is typically attributed to greater content of calpastatin, an inhibitor of protein degradation and tenderization. However, little is known regarding the mechanistic basis for greater calpastatin content and if other muscle properties differ among breed types. The objectives of this study were to evaluate muscle metabolic and contractile characteristics in Angus, Brangus, and Brahman cattle, and their relation to protein degradation and tenderness. Muscle from Brahman steers exhibited greater mitochondrial content, but paradoxically, this was not associated with corresponding changes in fiber contractile properties. A 14 d aging period was not sufficient to overcome the delayed activation of proteolysis observed in Brahman beef. Thus, earlier activation of calpain-1 is critical for promoting protein breakdown and enhancing tenderness of Brahman-influenced beef. Introduction Brahman genetics are utilized to convey heat tolerance, but Brahman cattle exhibit less desirable carcass and palatability traits. Despite improvements in genetic selection, beef from Bos indicus influenced cattle remains tougher and exhibits greater variation in tenderness than beef from Bos taurus cattle (Casas et al., 2006; Elzo et al., 2012). Toughness of Brahman-influenced beef is primarily attributed to the rate and extent of postmortem protein degradation during aging. In the aging period, proteases disrupt the structural integrity of muscle cells, thereby contributing to tenderization. The protease calpain-1 appears responsible for the majority of postmortem proteolysis. Calpain-1 is activated by an increase in cellular calcium concentration, and it is inhibited by calpastatin. Previously, others have documented that Brahman and Bos indicus-influenced cattle exhibit higher calpastatin activity compared to Bos taurus breeds, leading to diminished protein degradation and tougher beef. Genetics, breed, and other factors may influence muscle fiber characteristics. However, the mechanistic basis for increased calpastatin content is not known, and its relationship to other muscle fiber characteristics has not been established. While the calpain/calpastatin system is undoubtedly important to tenderization, several aspects of the conversion of muscle to meat remain relatively unexplored; further investigation may aid in understanding the development of meat quality traits. After harvest, hypoxic/ischemic conditions lead to generation of reactive oxygen species, which may trigger programmed cell death, or apoptosis. Recent evidence supports that the calpain system may interact with caspases, the proteases involved in cell death signaling (Kemp and Parr, 2012). Mitochondria are also involved in these cell death pathways, indicating that metabolic properties of muscle fibers may play an important role in dictating the cellular environment in postmortem muscle. Therefore, our objectives were to evaluate contractile and metabolic characteristics of muscle and determine their association with proteolysis and tenderness in cattle varying in Brahman composition Florida Beef Research Report

32 Materials & Methods Animal breeding and management Cattle used in this study were part of the long-term multibreed Angus-Brahman project at the University of Florida and represent a continuous spectrum of Angus-Brahman genetic variation. Calves were born between November and February, castrated at birth, and weaned in August. Preweaning calves were kept with their dams on bahiagrass pastures at the UF Beef Research Unit and provided free access to mineral supplement. Yearling steers were transported to a contract feeder (Suwannee Farms, O Brien, FL in 2015; Quincey Cattle Company, Chiefland, FL in 2016) and provided a standard commercial corn-protein diet with vitamins and minerals. In years 2015 and 2016, a subset of steers at the feedlot was selected for one of three slaughter dates. Steers from Angus (80-100% Angus; 0-20% Brahman), Brangus (62.5% Angus, 37.5% Brahman), and Brahman (0-20% Angus; % Brahman) groups from 2015 and 2016 were included in this analysis. Slaughter and sample collection Steers (n=2 per breed per day; 18 total each year) were harvested under USDA-FSIS inspection at the UF Meat Lab. Samples from the longissimus (loin) muscle were collected at 1.5 h, 24 h, 7 d, and 14 d postmortem. At 48 h, two 1-inch steaks were removed, vacuum packaged, and aged for 7 d or 14 d. Steaks were used for objective tenderness (Warner-Bratzler shear force, WBSF) and subjective tenderness by a trained sensory panel according to Wright et al. (2018). Muscle fiber characteristics Muscle fiber metabolic properties were assessed using activity of citrate synthase, a marker for mitochondrial content, according to procedures outlined by Scheffler et al. (2014) and Wright et al. (2018). Muscle contractile type was established using immunohistochemical detection of myosin heavy chain proteins according to Wright et al (2018). Proteolyis Conversion of calpain-1 from its full-length form to a shorter fragment (76 kilodalton, kda) was used as an indicator calpain activation. Degradation of a muscle protein (troponin T) was determined by evaluating conversion of intact form to degradation products. These changes in protein size and amount were assessed by Western blotting according to Wright et al. (2018). Statistical analysis Data were analyzed using analysis of variance in SAS-JMP with breed group as a fixed effect. Years were analyzed separately. Data presented are least square means of each breed group ± standard error (SE). Means of breed groups were compared using Tukey s adjustment for multiple comparisons. Results Brahman influence is associated with increased toughness of beef loin steaks. Brahman steaks exhibited greater shear force than Angus in 2015, but not 2016 (Table 1); in comparison, sensory panelists consistently evaluated Brahman steaks as tougher than Angus steaks. Because tenderization is related to both the rate and extent of postmortem proteolysis, we evaluated activation of the protease calpain-1 at 24 h as an indication of early rate of protein degradation (Figure 1). Activation of calpain-1 was numerically lowest in Brahman in both years, and differed (P<0.05) from Angus in 2015 and Brangus in In the 2016 cohort, activation of calpain-1 was virtually complete in all breed groups by 7 d (not shown). However, calpain-1 activity may be gradually lost during this period. In this case, the delay in calpain-1 activation early postmortem may contribute to reduced protein degradation at 14 d. The extent of protein degradation at 14 d, indicated by troponin T degradation, was reduced in Brahman compared to Angus and Brangus (Figure 3; P<0.05). In the 2015 set, troponin T degradation at 14 d was associated with WBSF (R 2 = 0.48, P=0.001) and sensory tenderness (R 2 = 0.69, P<0.0001), consistent with the concept that diminished protein degradation is a primary factor driving toughness of Brahman beef Florida Beef Research Report

33 The early postmortem period is particularly critical to instigating calpain activation and protein degradation. Mitochondria may regulate cell death and influence cellular calcium levels early postmortem. Citrate synthase activity, a marker of mitochondrial content, was higher in Brahman muscle compared to Angus (Table 2, P = 0.005). Oxidative (mitochondrial) metabolic capacity typically corresponds with expression of certain type 1 or 2a fiber types and smaller cross sectional area. Although breed group influenced frequency and cross sectional area of 2x fibers, results were not consistent with metabolic data. Contrary to expectation, Brahman possessed larger 2x fibers compared to Angus. Mitochondria content and functional parameters may contribute to early postmortem metabolism and meat quality development by regulating cell death pathways and intracellular calcium concentrations. Further work is aimed at investigating the how mitochondria content and function influence early postmortem processes during the conversion of muscle to meat. Literature cited Casas et al J. Anim. Sci. 84: Elzo et al Meat Sci. 90: Kemp and Parr Meat Sci. 92: Scheffler et al Amer. J. Phys.-Cell Phys. Wright et al Meat Sci. 135: : C354-C Florida Beef Research Report

34 Table 1. Effect of Brahman influence 1 on instrumental (Warner-Bratzler shear force, WBSF) and trained sensory panel evaluations of tenderness of loin steaks. Breed group Angus Brangus Brahman SE P-value 2015 WBSF, 14d (lb) 7.96 b 9.51 ab a Sensory tenderness a 5.60 a 4.01 b WBSF, 7d (lb) WBSF, 14d (lb) Sensory tenderness 5.42 a 5.01 ab 4.24 b Breed composition: Angus = % Angus (0-20% Brahman); Brangus = 62.5% Angus, 37.5% Brahman, and Brahman = % Brahman (0-20% Angus). 2 Sensory tenderness: 1 = extremely tough, 2 = very tough, 3 = moderately tough, 4 = slightly tough, 5 = slightly tender, 6 = moderately tender, 7 = very tender, 8 = extremely tender. a,b means lacking a common superscript differ (P<0.05). Calpain-1 activation at 24h Proportion of activated calpain a ab b ab a b Angus Brangus Brahman Figure 1. Calpain-1 activation in longissimus (loin) muscle at 24h postmortem. Activation was determined by evaluating the proportion of autolyzed calpain-1 relative to total, which is indicative of its activity. a,b means lacking a common superscript differ (P<0.05) Florida Beef Research Report

35 Degradation of Troponin T at 14d Degradation (products rel. to total) a a a a b b Angus Brangus Brahman Figure 2. Degradation of the protein troponin T after 14d aging in longissimus (loin) muscle of steers differing in Brahman composition. Degradation was calculated by determining signal of degradation products relative to total (degradation products + intact protein). a,b means lacking a common superscript differ (P<0.05). Table 2. Effect of Brahman influence 1 on metabolic and contractile characteristics of longissimus muscle. 2 Breed group Angus Brangus Brahman SE P-value Metabolic characteristic Citrate synthase activity (nmol/min/mg) 5.11 a 6.43 ab 7.26 b Contractile characteristic Type 1, % Type 2a, % Type 2x, % 48.7 a 40.8 b 45.4 ab Type 2x, CSA b 4626 ab 5577 a Breed composition: Angus = % Angus (0-20% Brahman); Brangus = 62.5% Angus, 37.5% Brahman, and Brahman = % Brahman (0-20% Angus). 2 Data are from 2015 only. 3 Represents frequency of a given fiber type relative to total number of fibers evaluated. 4 Cross-sectional area a,b means lacking a common superscript differ (P<0.05) Florida Beef Research Report

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37 Upcycling Bahiagrass Hay Using Cull Potatoes in an Ensiling System Tim Wilson 1, Matt Hersom 2, Mark Warren 3, Gary England 4, David Baggett 4 Synopsis Combining bahiagrass hay and cull potatoes is a viable option to increase the nutritive value of bahiagrass hay and utilize cull potatoes. Up-scaling to farm sized feeding is necessary to validate this conclusion. Summary A proof of concept demonstration was conducted to examine the use of cull potatoes and bahiagrass hay to create an ensiled feed resource for cattle. Bahiagrass and potatoes were layered in plastic drums and sealed under vacuum for 72 days to undergo an ensiling process. Samples of the final product were collected and analyzed for nutritional composition. Dry matter content of the final product was less than desired. Energy values on a dry matter basis of the ensiled product were less than predicted, however when expressed on an as fed basis energy values were greater than predicted. Fermentation profiles and acid concentrations indicate a marginal fermentation process. Proof of concept was successful with this demonstration. Up scaling this demonstration to a small-scale, on-farm demonstration would seem warranted. Introduction Too often, the harvest of conserved forage for hay becomes a postponed event that happens late in the growing season when the weather is more predictable and the forage yield is maximal. This practice too often results in poor-quality hay that requires additional supplementation to meet the nutritional requirements of mature gestating and lactating cows. An inexpensive means of improving the value of bahiagrass forage would increase the value of this feed resource and decrease the total expense assigned to feeding the cow herd. In Northeast Florida, table stock or fresh market potatoes are harvested between late April and early June. Large amounts of cull potatoes are generated by these operations. Being high in moisture and energy these cull potatoes are relatively unstable and need to be removed from the grading and packing facilities in a timely manner to avoid contamination from spoiled potatoes. Today many of these potatoes are being fed fresh to cattle during the harvest season. This practice both reduces the environmental contamination on the vegetable farm and also provides a low-cost nutrient source for local cattlemen. On a dry matter basis, potatoes have a nutritional profile similar to that of corn with a crude protein content of 9-10% and TDN around 80%. Potatoes are high in moisture (~75%) compared to corn and other grains (<10%), so it requires about 400 pounds of fresh potatoes to equal the dry matter of 100 pounds of grain. A significant amount of work has been done in other potato producing regions of the country to ensile potatoes combining them with low quality stored forages. Typically the high moisture, low fiber potatoes are ground and mixed with dry chopped forages (oat or wheat straw) to create a material that is approximately 60-65% dry matter. This upcycling of low-quality forage by using an available cull crop has potential to be implemented in Florida. This initial project was conducted to determine the feasibility of upcycling bahiagrass hay through the addition of cull potatoes and ensiling the final product as a means of conserving the final product for later use. The intent of the project was to upcycle the bahiagrass hay and to extend the storage life of the cull potatoes. If successful this system could optimized nutrient availability and use efficiency Florida Beef Research Report

38 Materials and Methods One bahiagrass large round bale of hay was used for the demonstration. Cull potatoes originated from the UF/IFAS Hastings Agricultural Extension Center. Hay and potatoes were sampled prior to initiation of the project and analyzed at a commercial laboratory (DairyOne, Ithaca, NY). Two treatments were utilized to examine the feasibility of the hay-potato ensiling product. Treatment one (Trt1) was a combination of 25% hay and 75% cull potatoes. On an as-fed basis 7.3 lbs of hay and 22 lbs of potatoes were combined. Treatment two (Trt2) was a combination of 20% hay and 80% cull potatoes. On an as-fed basis, 5.5 lbs of hay and 22 lbs of potatoes were combined. For each treatment two 55-gal and one 35-gal plastic barrels with lids were utilized. Hay was peeled off of the hay bale and potatoes were rough chopped through a wood chipper. Hay and potatoes were alternately layered into a barrel and compressed using a front-end loader of a tractor. After the sixth layer, barrels were sealed with a matching lid fitted with a check-valve and a vacuum applied to remove as much air as possible to create an anaerobic environment. Sealed barrels were placed in a three-sided shed. After 72 days barrels were opened and samples taken via a tube silage core-sampler. Two cores from each barrel were collected for analysis. Each sample was sealed in a re-sealable plastic bag and placed on ice for transport to the laboratory and subsequently frozen. Subsamples of each sample were sent to a commercial laboratory for chemical and fermentation analysis (DairyOne). Comparisons of ensilage treatments was conducted with the Mixed procedure of SAS. Model included ensiling treatment and replication. Least squares means are reported. Results A summary of the hay, Trt1, and Trt2 is presented in Table 1. The hay utilized for the demonstration was typical of what might be sourced in Florida. The lone notable exception is 61% TDN value which might be considered greater than average. Dry matter content of the Trt1 and Trt2 were 50% below the goal of a 60-65% dry matter product. The lower than anticipated dry matter of the products likely led to the marginal fermentation profile of both treatments. The lower than anticipated dry matter is somewhat puzzling in light of the 93% dry matter hay and 70% dry matter potatoes. One potential explanation could be the large amount of headspace that remained in the barrels used to store the treatments allowed for the accumulation moisture as a result of aerobic respiration rather than complete anaerobic fermentation as desired. Energy values on a dry matter basis are below expectation (Trt1 = 67% TDN, Trt2 = 80% TDN) based on the proportions used. However, when energy values are expressed on an as fed basis energy values (Trt1 = 58% TDN, Trt2 = 59% TDN) are greater than predicted. In contrast, crude protein values for Trt1 are greater than predicted and equal for Trt2. This outcome may be indicative of the similar protein value between the hay and potatoes, and minimal change of protein status associated with fermentation. Starch concentrations are indicative of the addition of potatoes, but incomplete fermentation of the starch to lactic acid that would preserve the product. A nearly 50% greater (P = 0.11) amount of starch in Trt2 compared to Trt1 likely indicates that fermentation of starch was limited. Limited fermentation could be surmised by the similar (P = 0.92) lactic acid, but nearly 50% decreased (P = 0.06) in total acid production in Trt2 compared to Trt1. It should be noted that the greater amount of total acids is comprised of acetic and butyric acid (data not shown) which are indicative of a poor fermentation outcome. Fiber fractions (ADF and NDF) of Trt1 and 2 are indicative of dilution of the hay fiber with potatoes. The decrease in fiber fractions could be predictive of increased digestibility (ADF) and increased dry matter intake potential (NDF) compared to the original hay. This conclusion must be taken with caution as no measure of digestibility or intake was established with this demonstration. A robust conclusion can t be drawn from this data as to the superiority of one treatment compared to the other. A primary issue is the dry matter content of the Trt1 and Trt2. Different outcomes of the dry matter content might have altered the fermentation outcome of the products. However, based upon the outcome of this proof of concept demonstration either proportion may hold promise for use as feedstock for cattle production. Selection of the higher potato proportion facilitates increased use of an available by-product, increases the total energy concentration of the product, moderates the occurrence of ammonia-n production, and indicates a greater potential for dry matter intake of the product. Potential areas of Florida Beef Research Report

39 alteration to the demonstration would include utilizing ground hay, hay of lower quality, greater processing of the potatoes, and an inoculant to stimulate fermentation. Proof of concept was successful with this demonstration. Up scaling this demonstration to a small-scale, on-farm demonstration would seem warranted. Up scaling the demonstration will involve grinding multiple bales of hay, processing a larger amount of potatoes, construction of a ensiling facility (likely a bunker), other procedures relevant to silage production, and ultimately cattle to offer the product. None of the aforementioned issues appears to be insurmountable hurdles that would prevent success. Table 1. Comparison of upcycled bahiagrass hay and potato ensiled mixture to bahiagrass hay Hay:Potato Mixture Item Trt 1 1 Trt 2 2 SEM P-value Hay 3 Potato Diff. Hay and Trt1 Diff. Hay and Trt2 Dry Matter, % analysis on DM basis TDN, % Net Energy maintenance, mcal/lb Net Energy gain, mcal/lb Crude Protein, % ADF, % NDF, % Ammonia, % Ammonia-N, % Total Nitrogen Starch, % ph Lactic Acid, % Total Acid, % DMI Potential Trt1: 25:75 hay to potato proportion ensiled for 72 days. 2 Trt2: 20:80 hay to potato proportion ensiled for 72 days. 3 Bahiagrass hay. 4 Total digestible nutrients. 5 Acid detergent fiber. 6 Neutral detergent fiber. 7 Dry matter intake potential = 1.1 x cow body weight / %NDF. A body weight of 1200 lbs was used Florida Beef Research Report

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41 Comparison of Trace Mineral Source on Cow Trace Mineral Status, Reproduction, and Calf Weaning Weight on Two Commercial Ranches M. Hersom 1, J. Yelich 1, M. Irsik 2 Synopsis Supplementation with organic trace mineral improved cow pregnancy rate and calf weaning weight compared to inorganic trace mineral sources. Liver trace mineral concentration varied over time in the production season regardless of trace mineral source. Summary Trace mineral source technology was evaluated using two, adjacent, large, south-florida ranch cowherds (designated as Ranch A and Ranch B). Over two consecutive years two mineral supplements containing either inorganic (ING, sodium selenite and salt sulfates) or full replacement with organic source (ORG, proteinates and yeast sources) trace minerals were compared. Trace mineral supplements delivered as loose mineral in a free choice application. Pregnant cows grazed bahiagrass pastures and were supplemented with other feedstuffs to maintain cow body condition score as determined by the participating ranches. Cow pregnancy rate was collected from both ranches in year 1 and only Ranch A in year 2. Calf weaning weight was collected from Ranch A in both years. Cow mineral liver status was collected from both ranches in year 1 and Ranch A in year 2. When evaluated over two years and both ranches, ORG cows had greater breeding season pregnancy rate (95.3%) compared to ING cows (92.6%). Calves from cows supplemented with ORG weaned an average of 548 lb calf compared to 523 lbs for calves from cows supplemented with ING (P = 0.009), an improvement of 25 lbs of weaning weight. Organic trace minerals appear to be permissive to positive cow and calf performance, but cow age and body condition score are influential drivers in the overall system. Introduction Trace minerals have traditionally been supplemented to cattle diets as inorganic salts. In spite of this tradition, recent attention has been placed on the use of organic or chelated trace mineral supplementation in the rumen diets. Organic trace minerals differ from inorganic forms as a result of their chemical association with an organic ligand. Numerous groups of these organic trace minerals are formed from this mineral-organic ligand combination, which are available in the animal feeding industry and include chelates, proteinates, and complexes (AAFCO, 2000). The recent attention towards organic mineral supplementation in ruminant diets has been fueled by numerous studies that have shown an increase in overall performance in cattle supplemented with organic minerals. It is generally accepted that this association is due to the increased bioavailability of organic minerals. Minerals play a significant role in many metabolic processes that affect growth performance, reproductive efficiency and immune function. Selecting the correct mineral supplement is crucial for maintaining these processes. With research clearly demonstrating across animal species that organic minerals are move bioavailable to the animal further investigation is imperative to determine whether the greater bioavailability of these organic mineral will have a more positive effect on the overall performance of beef cattle reproduction. The object of this study was to evaluate the effect of pre- and postpartum trace mineral supplement source on cow pregnancy rate, cow liver mineral status, and calf weaning weight in a commercial beef cattle production setting. Materials and Methods Trace mineral source technology was evaluated using two, adjacent, large, south-florida ranch cowherds (designated as Ranch A and Ranch B). Over two consecutive years two mineral supplements containing either inorganic (ING, sodium selenite and salt sulfates) or full replacement with organic source (ORG, 1 Department of Animal Sciences, University of Florida, Gainesville, FL 2 College of Veterinary Medicine, University of Florida, Gainesville, FL Florida Beef Research Report

42 proteinates and yeast sources) trace minerals were compared. Trace mineral supplements delivered as loose mineral in a free choice application. Pregnant cows grazed bahiagrass pastures and were supplemented with other feedstuffs to maintain cow body condition score as determined by the participating ranches. In year 1, supplementation began approximately 90 days prior to calving and continued to weaning on both ranches. In the year 2 only Ranch A participated and trace mineral supplementation occurred from conception through weaning. Cow pregnancy rate was collected from both ranches in year 1 and only Ranch A in year 2. Calf weaning weight was collected from Ranch A in both years. Cow mineral liver status was collected from both ranches in year 1 and Ranch A in year 2. Ranch A utilized cows between 3 to 10 years of age, Ranch B used predominately older mature cows. In total over 2 years using 3 groups of cows, 973 cows were allotted to inorganic trace mineral treatment and 916 cows were allotted to the organic trace mineral treatment. Breeding seasons were days and pregnancy was determined 60 days after the breeding season at each ranch. The ING trace mineral supplement was formulated to meet the mature beef cow mineral requirements based on NRC recommendations (Table 1). The ORG trace mineral supplement was formulated to meet beef cow NRC requirements based on the assumption of greater bioavailability for organic sources of minerals. A subset of cows was used to collect liver biopsies for liver mineral analysis. Liver tissue samples were analyzed for trace mineral concentration of cobalt (Co), copper (Cu), iron (Fe), manganese (Mn), molybdenum (Mo), selenium (Se), and zinc (Zn) and was carried out using ICP-Spectroscopy-MS (DCPAH, Lansing, MI) on three collection points: pre-calving (PreC), post-calving (PostC), and weaning. Cow data were analyzed with the Mixed procedure of SAS using a repeated measures analysis. Fixed effects included mineral source treatment, time, and appropriate interactions. Calf weaning weight was data was adjusted to account for differential sizes of groups weighed at weaning and analyzed with the Mixed procedure of SAS. Fixed effects included mineral source treatment. Results Pregnancy rate, a key driver for cattle enterprise profitability was exceptionally good for both ranches (Table 2). There were no differences (P<0.44) between trace mineral sources for Ranch A in either year. Whereas Ranch B had greater (P = 0.006) pregnancy rate in cows supplemented with ORG compared to ING cows. When evaluated over two years and both ranches, ORG cows had greater (P = 0.01) breeding season pregnancy rate (95.3%) compared to ING cows (92.6%). There was also a significant mineral source effect on weaning weights collected from Ranch A. Calves from cows supplemented with ORG weaned an average of 548 lb calf compared to 523 lbs for calves from cows supplemented with ING (P = 0.009), an improvement of 25 lbs of weaning weight. The majority of this improvement came in heifers from ORG that weighed 31 lbs more (P = 0.02) than heifers from ING. The difference between mineral sources for steer weaning weight was significant (P = 0.17), but 18 lbs greater for ORG mineral steers. Cow liver cobalt concentration was not affected by source, time, or year (P>0.05), mean cobalt concentration was 0.22 μg/g. Liver copper concentration exhibited a year x source x time effect (P<0.05). Copper declined over time within Year 1 for both ranches. Liver copper concentration in Ranch A cows was less in Year 2 compared to Year 1. Cow liver iron concentration was greater (P<0.05) at Pre-calving compared to other sampling dates. Manganese demonstrated a time effect (P<0.05) and a year effect (P<0.05). A clear time pattern for manganese is not evident at either ranch, but liver concentrations were greater in Year 1 than Year 2. Molybdenum demonstrated no statistical differences (P>0.05). Selenium exhibited a year x source x time (P<0.05) effect. Selenium concentration in the liver were greater in ORG than ING, was lowest at Post-calving compared to Pre-calving, and greater in Year 1 than Year 2. Zinc liver concentration exhibited a year x time (P<0.05) and source x time (P<0.05) effects. In Year 2 liver Florida Beef Research Report

43 concentrations were greater at weaning compared to post-calving. Throughout the production cycle liver zinc concentration changed in a different patter for ORG compared to ING cows. Organic trace minerals appear to be permissive to positive cow and calf performance, but cow age and body condition score are influential drivers in the overall system. Literature Cited AAFCO Official Publication. Association of American Feed Control Officials, Inc Florida Beef Research Report

44 Table 1. Composition of trace mineral supplement provided to cows Component Inorganic Organic Dry matter, % Ca, % P, % NaCl, % Mg, % K,% S,% Co, ppm Cu, ppm 1,012 1,003 I, ppm Fe, ppm 7,565 7,567 Mn, ppm 1,087 1,104 Se, ppm Zn, ppm 3,239 3,246 F, ppm Vitamin A, IU/lb 206, ,464 Vitamin D, IU/lb 5,670 5,670 Vitamin E, IU/lb Table 2. Effect of trace mineral source on cow pregnancy and calf weaning weight Trace Mineral Supplement Source Organic Inorganic P-value Cow Pregnancy Rate Ranch A, year % (337/356) 93.3% (334/358) 0.65 Ranch A, year % (268/280) 95.3% (262/275) 0.44 Ranch B, year % (268/280) 90.0% (306/340) Total 95.3% (873/916) 92.6% (901/973) 0.01 Calf Weaning Weight, lbs Heifers Steers Average Florida Beef Research Report

45 Table 3. Effect of trace mineral supplement source and time on cow liver trace mineral concentration (μg/g) Year 1 Year 2 Pre Calve Post Calve Wean Post Calve Wean SEM Effect Cobalt Ranch A ORG ING Ranch B ORG ING Copper Ranch A ORG ING Ranch B ORG ING Iron Ranch A ORG ING Ranch B ORG ING Manganese Ranch A ORG , 2 ING Ranch B ORG ING Molybdenum Ranch A ORG ING Ranch B ORG ING Selenium Ranch A ORG ING Ranch B ORG ING Zinc Ranch A ORG , 4 ING Ranch B ORG ING Year effect P< Time effect, P< Year x Time effect, P< Source x Time effect, P< Year x Source x Time effect, P< Florida Beef Research Report

46 Florida Beef Research Report

47 Effects of Prenatal and Postnatal Trace Mineral Supplement Source Provided To Gestating Angus and Brangus Cows over Two Production Cycles on Performance and Trace Mineral Status of Cows D. Price 1, M. Hersom 1, J. Yelich 1, M. Irsik 2, O. Rae 2 Synopsis The results of this experiment suggest that assessment of an animal s trace mineral status should preferentially be carried out in liver tissue. The source of trace mineral supplementation provided to gestating and lactating cows had minimal effects on cow performance. Summary A 2 2 factorial arrangement of trace mineral (TM) source and breed utilized Angus (AN) and Brangus (BN) cows supplemented with inorganic (ING, salt sulfate) or organic (ORG, proteinates and Se-yeast) forms of Co, Cu, Mn, Se, and Zn over two production cycles to evaluate liver and serum TM status, and performance of cows. Supplementation initiated 82 ± 2 d prior to calving in yr 1 and was fed as a pellet until breeding with the total TM amount divided equally and fed 3 times/wk at 1.0 lb 1000 lb BW -1 cow - 1 d -1, after which loose mineral was fed through weaning at 4 oz 1000 lb BW -1 cow -1 d -1. Cows remained on same TM sources for yr 2 and received TM as a pellet from post-weaning to breeding and as loose mineral from breeding to weaning. Cows (n = 25 in yr 1 and 24 in yr 2) had serum and liver collected for TM analysis prior to TM initiation (yr 1 only), at pre-calving, breeding, and weaning. Cow BW and BCS were not affected (P>0.05) by TM source, but varied over time (P<0.05). Liver Se was greater (P<0.05) in ORG compared to ING cows in yr 2. Breed differences were observed for cow liver Cu (yr 1) and Mn (both yrs), with greater (P<0.05) concentrations in BN compared to AN, suggesting differences in Cu and Mn absorption and/or utilization may be present. The TM source provided to gestating and lactating cows had minimal effects on cow performance and inconsistent effects on cow reproduction and calf performance. Introduction Trace minerals (TM) are essential components in biochemical, physiological, immunological, and metabolic processes in an animal s body (Suttle, 2010). Sufficient concentrations of circulating and stored TM are necessary for proper growth, reproductive and immune functions in animals, while deficiencies result in decreased growth, innate and adaptive immunity (Spears, 2000), fertility and reproductive functions in males and females (Hidiroglou, 1979). Moreover, as the gestating dam supplies nutrients to the fetus in utero, TM deficiencies of the dam may impact the health and production potential of its future offspring (Ashworth and Antipatis, 2001; Hostetler et al., 2003). An animal s TM status may be influenced by the animal s age, breed or genetics, health status, or amount of TM or TM antagonists consumed, and even the season of the year (Miranda et al., 2006; Suttle, 2010). Additionally, the form of the TM, either as inorganic or organic may impact its bioavailability and ultimately its utilization by the animal (Spears, 2003). Supplementation of the gestating and lactating dam and the effects on offspring TM status warrant investigation. Therefore, the hypothesis of this experiment was that supplementation of pregnant cows with ORG compared to ING TM during the pre-and postnatal periods would improve cow performance, reproduction and maintenance of TM status, and improve neonatal and growing calf TM status and performance through weaning. Materials and Methods Over two production cycles (yr 1 and yr 2), a 2 2 factorial arrangement of TM source (inorganic vs. organic) and breed (Angus vs. Brangus) utilized pregnant cows to investigate the effect of prenatal and Florida Beef Research Report

48 lactating cow TM supplement source on cow reproductive performance, BW, BCS, and TM status, and calf performance and TM status from birth to weaning. In yr 1 of the experiment, a total of 199 cows were blocked by breed (Angus, AN = 99; Brangus, BN = 100), gestation length, age, BW, and BCS (scale 1 = emaciated, 9 = extremely fat; Wagner et al., 1988) and allocated randomly to receive either 1) inorganic minerals (ING, n =100) with Na selenite and Co, Cu, Mn, and Zn in salt sulfate forms, or 2) organic minerals (ORG, n = 99) with Se-yeast (Sel-plex, Alltech, Nicholasville, KY) and Co, Cu, Mn, and Zn complexed as proteinates (Bioplex, Alltech, Nicholasville, KY). The experimental design resulted in the following four treatment groups: ING-AN (n = 49), ING-BN (n = 51), ORG-AN (n = 50), and ORG-BN (n = 49). Both TM supplements were formulated to meet NRC requirements and were manufactured in either a single pellet or loose mineral batch by the Lakeland Nutrition Group (Lakeland, FL). The TM supplementation was initiated 82 ± 2 d prior to parturition in yr 1 and supplements were fed as a wheat middling based pellet, which was delivered at a rate of 1.0 lb 1000 lb BW -1 cow -1 d -1. The supplement was divided equally and fed 3 times per week (Monday, Wednesday, and Friday) in feed bunks until start of the breeding season. Thereafter, the TM source was offered as a loose mineral supplement on a free choice basis at a rate of 4 oz cow -1 d -1 until weaning. Cows were maintained in 12 pastures (3 per treatment) of approximately ac from the initiation of the trial until the start of the breeding season. Cows had ad libitum access to water and hay throughout the experiment and were fed stored forage (bermudagrass hay, Cynodon dactylon) and supplemented with soybean hulls as needed to maintain a mean cow BCS of 5.0 from initiation of TM supplementation until the start of the breeding season when cows were maintained in four breeding groups (one per treatment) and grazed on bermuda and bahiagrass pastures until calves were weaned. In yr 2 of the experiment, cows (n = 161; ING-AN = 41, ING-BN = 44, ORG-AN = 38, and ORG-BN = 38) remained on the same TM supplement source they were assigned in yr 1 of the experiment and were fed the TM supplement as a wheat middling pellet from post-weaning through breeding and as a loose mineral from breeding to weaning. The TM supplements were fed at an equivalent rate and frequency as in yr 1 of the experiment. Cows were fed stored forage (i.e., bermudagrass hay) and supplemented with soybean hulls as needed to maintain a mean cow BCS of 5.0 from initiation of TM supplementation until the start of the breeding season each year. Cows and calves had ad libitum access to water and hay throughout the experiment and were maintained in 8 bahiagrass pastures (2 pastures per treatment group) from post-weaning in yr 1 until breeding (yr 2) when they were combined into 4 bermuda and bahiagrass pastures (1 pasture per treatment group) until calves were weaned. Daily intake was not measured in yr 1 or yr 2, though each pen consumed all feed that was offered over both years of the trial. Analysis of TM supplements, feed, and forage, and pasture offered to the cows was carried out at a commercial laboratory (Dairy One, Ithaca, NY) and averages from both years are presented in Table 1. To determine cow TM status over yr 1 of the production cycle a subset of multiparous Angus and Brangus cows were selected out of each treatment based on calving date, BW and BCS and had liver biopsy samples and blood collected at 4 time points over the production cycle: prior to mineral supplementation (pre-min, d -20), pre-calving (d 57), breeding (d 155), and at weaning (d 287). All cows on the trial had BW and BCS recorded at pre-min, pre-calving, breeding, and at weaning for determination of cow performance. Along with the cows used for production cycle liver and serum TM status, an additional 17 cows (total of 42) were selected out of the 4 treatments based on expected calving date, BW, and BCS at the initiation of TM delivery, and utilized at calving and at 30 d post-calving to determine calf serum TM concentrations. This resulted in the following subset of calves ING-AN = 10, ING-BN = 11, ORG-AN = 11, and ORG-BN = 11. One ORG-BN cow had twins. In yr 2, a total of 24 cows (6 per treatment) were selected out of each treatment group based on expected calving date, age, BW, and BCS for liver biopsy collection at 3 time points (pre-calving, breeding, and weaning) of the production cycle. There was no pre-min sample in yr 2, since all cows had been on their respective TM treatments from the previous yr of the experiment Florida Beef Research Report

49 Blood samples for TM analysis were collected for TM analysis. All TM analysis (Co, Cu, Fe, Mn, Mo, Se, and Zn) for serum and liver (dry matter basis) was carried out by a commercial laboratory (DCPAH, Michigan State University, Lansing, Michigan). Statistical Analysis Data were analyzed in SAS 9.4 (SAS Institute Inc., Cary, NC) with cow or calf as the experimental unit where appropriate. The random statement included cow (or calf) nested within TM source breed. The cow BW and BCS data were analyzed separately for yr 1 and yr 2 by repeated measures PROC MIXED with fixed effects of TM source, breed, time, and their interactions. Cow age was included as a covariate in the yr 1 BW and BCS analysis and considered significant when P Cow serum and liver TM data were analyzed by repeated measures PROC MIXED with fixed effects of TM source, breed, time, and their interactions. Natural logarithm transformations where used on TM concentrations when necessary. The P-values are from the natural logarithm data are presented along with the back calculated LSMEANS. Natural logarithm transformations where used on TM concentrations when necessary. The P- values are from the natural logarithm data are presented along with the back calculated LSMEANS. Pearson correlations between serum and liver TM concentrations used PROC CORR. Data are presented as LSM ± S.E. Results Cow Production Cycle Performance Cow BW and BCS over yr 1 and yr 2 of the production cycle are presented in Table 2. In yr 1, there was no affect (P>0.05) of TM source, breed, TM source breed, nor TM source time on cow BW over the production cycle. However, as expected cow BW varied (P<0.001) across the production cycle, as cows weighed more at pre-mineral and pre-calving than at breeding or at weaning. A breed time, and TM source breed time effect occurred (P = 0.01) for cow BW (yr 1); however, cow BW did not differ at any individual time points, rather the breeds and treatments changed relative rank. Year 2 cow BW varied (P<0.001) over time but was not (P>0.05) affected by TM source, breed or any interactions. Cow BCS was affected (P<0.001) by time during both years of the experiment, where cow BCS was greatest pre-calving. There tended (P = 0.08) to be a TM source time (yr 1) effect; however, cow BCS for all treatments remained within 0.3 BCS at all time points. Year 1 cow BCS was not affected (P>0.05) by TM source, breed or any other interactions. Year 2 BCS was affected (P<0.001) by breed time and tended (P<0.08) to be affected by TM source breed time as BN cows had greater pre-calving and breeding BCS compared to AN cows. Cow BCS did not differ between treatments at breeding or weaning. Similarly, yr 2 BCS varied (P<0.001) over time, but was greater (P = 0.02) in BN compared to AN when pooled across all time points. Cow Trace Mineral Status Year 1 Year 1 cow serum and liver TM concentrations over the production cycle pooled across TM sources and breeds are presented in Table 3 along with the pearson correlations between serum and liver values. With the exception of serum Co (P = 0.13), all serum and liver TM values varied (P 0.01) over time. Liver TM concentrations with the exception of Fe were decreased at breeding and at weaning, relative to their pre-calving values. Positive relationships between serum and liver values were observed (P<0.01) for Co, Mo, and Se when correlations were examined across all liver values and time points, Table 3. When serum and liver correlations were examined at individual sample times, Mo was only correlated (P<0.01) at weaning (r = 0.57), while Co was correlated (P 0.05) at all time points, and Se was correlated at all time points except (P = 0.76) at breeding. Serum Mn concentrations were greater (P = 0.05) in ING (2.18 ± 0.08 ng/ml) compared to ORG (1.96 ± 0.07 ng/ml) cows when pooled across time. Serum Co, Cu, Fe, Mo, Se and Zn were not affected (P>0.10) by TM source. The BN (2.18 ± 0.08 ng/ml) cows tended (P = 0.06) to have greater Mn Florida Beef Research Report

50 compared to AN cows (1.96 ± 0.07 ng/ml). Conversely, AN cows had greater (P = 0.02) serum Se (67.62 ± 2.43 ng/ml) and tended (P = 0.08) to have greater serum Zn (0.79 ± 0.02 µg/ml) than BN cows (59.04 ± 2.50 ng/ml, 0.73 ± 0.02 µg/ml for Se and Zn, respectively) when concentrations were pooled across time. Cow breed did not (P>0.10) affect serum Co, Cu, Fe and Mo values. Molybdenum was affected (P = 0.03) by TM source breed, as ING-BN (1.12 ± 0.19 ng/ml) had lesser serum Mo values than ORG- BN (1.83 ± 0.30 ng/ml), but ING-AN (1.72 ± 0.28 ng/ml) and ORG-AN (1.34 ± 0.20 ng/ml) cows did not differ from each other. There was no TM source breed effect (P>0.10) on serum Co, Cu, Fe, Mn, Se, and Zn concentrations. Greater (P<0.01) overall liver Cu concentrations were observed in ING (255 ± 14.4 µg/g) compared to ORG (190 ± 10.1 µg/g) cows and in BN (266 ± 14.5 µg/g) compared to AN (182 ± 10.0 µg/g) cows when concentrations were pooled across time. Concentrations of liver Mn were greater (P<0.01) in BN (11.25 ± 0.29 µg/g) compared to AN (9.69 ± 0.29 µg/g) cows. Cow TM source did not affect (P>0.05) liver Co, Fe, Mn, Mo, Se, and Zn, nor did breed affect (P>0.05) liver Co, Fe, Mo, Se, and Zn concentrations. Liver Co concentrations exhibited a TM source time effect (P<0.01, Figure 4-1), as ING cows had greater liver Co at weaning compared to ORG cows. When concentrations were pooled across time, liver Se concentrations tended (P = 0.06) to be affected by TM source breed, as Se concentrations differed between ING-AN (1.17 ± 0.08 µg/g) and ING-BN (1.48 ± 0.10 µg/g), but not ORG-AN (1.32 ± 0.08 µg/g), and ORG-BN (1.29 ± 0.08 µg/g). An effect of TM source time (P<0.01) occurred for Se liver concentrations (Figure 4-1) with greater Se concentrations in ORG cows pre-calving and greater concentrations in ING cows at breeding. There was no effect (P>0.05) of TM source breed on liver Co, Cu, Fe, Mn, Mo, and Zn, nor was there an effect (P>0.05) of TM source time for liver Cu, Fe, Mn, Mo, and Zn concentrations. Similar to serum Mo, concentrations of liver Mo were affected (P = 0.02) by a breed time (data not shown) and tended (P = 0.08) to be affected by TM source breed time (Figure 4-2), with the greatest liver Mo concentrations observed in ORG-BN cows at weaning. There was no effect (P>0.05) of breed time or TM source breed time for liver Co, Cu, Fe, Mn, Se, and Zn concentrations. Cow Trace Mineral Status Year 2 In yr 2, there was no effect (P>0.05) of TM source on cow liver Cu, Fe, Mo, and Zn concentrations. Breed did not affect (P>0.05) liver Co, Cu, Fe, Se, and Zn concentrations; although, BN cows had numerically greater Cu at all time points compared to AN cows. When pooled across time, mean liver Co (0.35 ± 0.02 µg/g) and Se (1.21 ± 0.05 µg/g) were greater (P 0.01) and Mn (11.26 ± 0.27 µg/g) tended (P 0.10) to be greater in ORG compared to ING (0.29 ± 0.02, 0.94 ± 0.04, ± 0.26 µg/g, respectively) cows. Additionally, mean Mn was greater (P<0.05) in BN (11.70 ± 0.26 µg/g) compared to AN (10.17 ± 0.27 µg/g) cows. With the exception of Fe (P>0.05), all liver TM concentrations were affected (P 0.05) by time. There was no TM source breed effect (P>0.05) for liver Co, Cu, Fe, Mn, Mo, and Zn concentrations. However, liver Se tended (P<0.10) to be affected by TM source breed, where ORG-AN (1.29 ± 0.07 µg/g) cows had greater (P<0.05) mean liver Se concentrations compared to ING-AN (0.91 ± 0.05 µg/g) and ING-BN (0.98 ± 0.05 µg/g) but did not differ (P>0.05) from ORG-BN (1.13 ± 0.06 µg/g) cows. There was no TM source time effect (P>0.05) on any liver TM concentrations. There was no breed time effect (P>0.05) on liver Co, Cu, Fe, Mn, and Se concentrations. There was a breed time, effect (P<0.05; data not shown) on liver Mo and Zn, where BN cows had greater (P<0.05) Mo at pre-calving (2.55 ± 0.12 µg/g) and weaning (3.09 ± 0.12 µg/g) compared to AN (2.22 and 2.69 ± 0.12 µg/g, respectively). Conversely, AN (142 ± 8.4 µg/g) cows had greater (P<0.05) Zn at weaning compared to BN (102 ± 6.1 µg/g) cows. There was no TM source breed time effect (P>0.05) on liver Co and Fe, Table 4. In contrast, liver Cu tended (P<0.10) to be affected by TM source breed time (Table 4), whereby at breeding, ORG-BN had lesser (P<0.05) Cu compared to ING-BN, but neither treatment differed (P>0.05) from ING-AN and ORG-AN. Additionally, liver Mn, Mo, Se, and Zn were affected (P<0.05) by TM source breed time, Table Florida Beef Research Report

51 Overall, the results of this experiment suggest that assessment of an animal s TM status should preferentially be carried out in liver tissue. Consistent correlations between serum and liver Co and Se concentrations indicate that determination of Co and Se status can be made based on serum samples if liver tissue is not available. The source of TM supplementation provided to gestating and lactating cows had minimal effects on cow performance. Moreover, breed differences were apparent in cow Cu and Mn concentrations and the mechanisms behind these differences warrant further examination. In conclusion, the TM source provided to gestating and lactating cows had minimal effects on cow performance. Literature Cited Ashworth, C., and C. Antipatis Reproduction. 122: Hidiroglou, M J. Dairy Sci. 62: Hostetler, C. E. et al Vet. J. 166: Miranda, M., et al Anim. Sci. 82: Spears, J. W J. Nutr. 133:1506S 1509S. Suttle, N., ed Mineral nutrition of livestock. 4th ed Florida Beef Research Report

52 Table 1. Trace mineral supplement, feed, and forage component analysis (DM basis) Pelleted mineral supplement 1,2 Free choice supplement 2,4 Composited samples 1 Item Inorganic Organic Inorganic Organic Soybean hulls Pasture 3 Hay DM, % CP 4, % TDN 4, % Ca, % P, % Mg, % K, % Na, % < < 0.01 S, % Co, mg/kg Cu, mg/kg I 4, mg/kg ,000 3, Fe, mg/kg Mn, mg/kg , Mo, mg/kg Se, mg/kg Zn, mg/kg ,230 1, Vitamin A 4, IU/kg 14,337 14,332 53,479 53, Vitamin D 34, IU/kg 1,286 1, Vitamin E 4, IU/kg Analysis of feedstuffs was carried out at Dairy One, (Ithaca, NY). Analysis of trace mineral supplements pellets is averaged across both years of the experiment. 2 Trace mineral supplements were formulated and manufactured as a single batch by Lakeland Nutrition Group (Lakeland, FL) and provided to cows in a pellet at 1.0 lb 100 lb BW -1 cow -1 d -1 and free choice mineral was provided at 4 oz cow -1 d Samples were collected monthly and composited for final analysis. 4 Formulation values for TM supplements Florida Beef Research Report

53 Table 2. Effect of an inorganic (ING) or organic (ORG) trace mineral (TM) supplement source provided to Angus (AN) and Brangus (BN) cows over two production cycles on cow BW and BCS TM Source Breed (B) P-value Item ING-AN ING-BN ORG-AN ORG-BN SEM TM B TM B T 1 TM T B T TM B T Year 1 Cows 2, n BW 3, lb pre-mineral 1142 y 1166 y 1147 y 1158 y < pre-calving 1246 z 1250 z 1255 z 1250 z 17.6 breeding 1114 x 1125 x 1109 w 1133 x 17.6 weaning 1098 w 1129 x 1125 x 1122 x 17.6 BCS 4 pre-mineral < pre-calving breeding weaning Year 2 Cows, n BW, lb pre-calving < breeding weaning BCS pre-calving < < breeding weaning T = Time 2 Cow age (P<0.01) used as a covariate for BW and BCS statistics in year 1. 3 Cow BW did not differ among treatments within any time point, (P>0.05). 4 Cow BCS measured on a scale of 1 = emaciated to 9 = extremely. w-z Means within a treatment differed across time, (P<0.05) Florida Beef Research Report

54 Table 3. Cow serum and liver (µg/g) trace mineral (TM) concentrations pooled across TM sources and breeds in year 1 of the production cycle (on a DM basis )1 Premin (d -20) Time (d) relative to TM initiation Pre-Calving Breeding (d 57) (d 155) Weaning (d 287) SEM P-Value Pearson Correlation 2 Item Co Serum, ng/ml 1.29 ab 1.05 a 1.11 ab 1.31 b Liver 0.34 b 0.36 b 0.36 b 0.29 a 0.02 < 0.01 < 0.01 Cu Serum, µg/ml 0.71 c 0.54 a 0.66 b 0.63 b 0.02 < Liver 229 a 242 a 182 b 232 a 12.5 < Fe Serum, µg/dl. 131 a 140 ab 154 b 5.9 < Liver 458 a 544 b 468 a 619 b 23.7 < Mn Serum, ng/ml 2.20 b 1.87 a 2.35 b 1.89 a 0.09 < Liver 9.61 a b b a 0.33 < Mo Serum, ng/ml 1.88 c 1.18 b 0.90 a 2.36 c 0.17 < Liver 2.97 bc 3.08 c 2.64 a 2.85 ab 0.09 < 0.01 < 0.01 Se Serum, ng/ml 60.2 b 70.5 c 71.3 c 51.4 a 2.03 < Liver 1.20 b 1.68 d 1.47 c 0.98 a 0.06 < 0.01 < 0.01 Zn Serum, µg/ml 0.77 b 0.71 a 0.75 ab 0.79 b Liver 118 a 148 c 113 a 134 b 3.5 < Time affected (P 0.01) all serum and liver TM concentrations except serum Co (P = 0.13). 2 Pearson correlations are on first line and P-values are on second line. a-d Means within a row with difference superscripts differed (P 0.05) Florida Beef Research Report

55 Serum Co, ng/ml A Serum Se, ng/ml B ING Serum ORG Serum ING Liver ORG Liver b y b x a a Pre-Min Pre-Calve Breed Time Wean y y x x ING Serum ORG Serum ING Liver ORG Liver Pre-Min Pre-Calve Breed Wean Time Liver Co, µg/g Liver Se, µg/g Figure 1. Serum and liver A) Co and B) Se in Angus and Brangus cows that were supplemented with inorganic (ING) or organic (ORG) trace minerals over the production cycle. a-b Serum means with different superscripts differed within that time point, (P 0.05). x-y Liver means with different superscripts differed within that time point, (P 0.05) Florida Beef Research Report

56 Serum Mo, ng/ml A ING-AN ING-BN ORG-AN ORG-BN b c a b b a, b a a a a a Pre-Min Pre-Calve Breed Wean Time ING-AN ORG-AN ING-BN ORG-BN b Liver Mo, µg/g a a a 2.0 Pre-Min Pre-Calve Rebreed Wean B Time Figure 2. Concentrations of Mo in A) serum and B) liver of Angus (AN) and Brangus (BN) cows that were supplemented with inorganic (ING) and organic (ORG) trace mineral sources over the production cycle. a-c Means with different superscripts differed within that time point, (P 0.05) Florida Beef Research Report

57 Table 4. Liver trace mineral (TM) concentrations (on a DM basis) in Angus (AN) and Brangus (BN) cows which received inorganic (ING) or organic (ORG) sources of trace minerals (TM) in year 2 of the production cycle Time (T) P-value Item 1 Pre-calving Breeding Weaning SEM TM B 2 T TM T B T TM B T Co, µg/g ING-AN < ING-BN ORG-AN ORG-BN Cu, µg/g ING-AN ING-BN ORG-AN ORG-BN Fe, µg/g ING-AN ING-BN ORG-AN ORG-BN Mn, µg/g ING-AN 7.95 ax az 9.84 aby < < ING-BN bxy aby ax ORG-AN bcy ay 9.22 bx ORG-BN 9.83 cx bz cy Mo, µg/g ING-AN 1.94 ax 2.79 y 2.76 aby < ING-BN 2.70 b ab ORG-AN 2.50 bx 3.19 y 2.62 ax ORG-BN 2.40 abx 2.74 x 3.15 by Florida Beef Research Report

58 Table 4. Continued Time (T) P-value Item 1 Pre-calving Breeding Weaning SEM TM B 2 T TM T B T TM B T Se 3, µg/g ING-AN 0.93 ax 1.00 ay 0.81 ax 0.08 < < ING-BN 1.10 ay 1.14 acy 0.74 ax ORG-AN 1.35 by 1.58 by 1.02 bx ORG-BN 1.16 by 1.24 cy 1.02 bx Zn 3, µg/g ING-AN 102 x 102 ax 167 ay ING-BN ab 95 b ORG-AN ab 121 c ORG-BN 105 x 130 by 110 bcxy 1 TM source breed, (P>0.05) for all TM concentrations. 2 B= breed. 3 Data were log-transformed before statistical analysis; back transformed means are presented. a-c Means within a column with different superscripts differed within, (P 0.05). x-z Means within a row with different superscripts differed within, (P 0.05) Florida Beef Research Report

59 Effects of Prenatal and Postnatal Trace Mineral Supplement Source Provided to Gestating Angus and Brangus Cows over Two Production Cycles on Performance and Trace Mineral Status of Calves D. Price 1, M. Hersom 1, J. Yelich 1, M. Irsik 2, O. Rae 2 Synopsis Supplementation of gestating and lactating cows with an organic source selenium source provided calves with greater selenium status from birth through the age of weaning in year 1 and at weaning in year 2. In year 1, organic trace mineral source calves had greater weaning weights, while in year 2, no differences in calf performance occurred based on trace mineral source. Summary A 2 2 factorial arrangement of trace mineral (TM) source and breed utilized Angus (AN) and Brangus (BN) cows supplemented with inorganic (ING, salt sulfate) or organic (ORG, proteinates and Se-yeast) forms of Co, Cu, Mn, Se, and Zn over two production cycles to evaluate liver and serum TM status, and performance of cows. Supplementation initiated 82 ± 2 d prior to calving in yr 1 and was fed as a pellet until breeding with the total TM amount divided equally and fed 3 times/wk at 1.0 lb 1000 lb BW -1 cow - 1 d -1, after which loose mineral was fed through weaning at 4 oz 1000 lb BW -1 cow -1 d -1. Cows remained on same TM sources for yr 2 and received TM as a pellet from post-weaning to breeding and as loose mineral from breeding to weaning. Calves had serum collected at 0, 12, 24 h, 30 d, 115 d of age and at weaning. Calf liver biopsy was collected on d 115 (yr 1) and weaning (both yrs). Calf serum, plasma, and liver Se were greater (P<0.05) in ORG compared to ING calves at all time points measured in both years. In yr 1, ORG calves had greater (P<0.05) weaning weights, while in yr 2, no differences (P>0.05) in calf performance occurred based on TM source. By supplementing cows during gestation and lactation with ORG Se, calf Se status can be increased through weaning compared to supplementation with an ING Se source. Introduction The form of the TM, either as inorganic or organic may impact its bioavailability and ultimately its utilization by the animal. Supplementation of the gestating and lactating dam and the effects on offspring TM status warrant investigation. Therefore, the hypothesis of this experiment was that supplementation of pregnant cows with ORG compared to ING TM during the pre-and postnatal periods would improve cow performance, reproduction and maintenance of TM status, and improve neonatal and growing calf TM status and performance through weaning. Materials and Methods Cow trace mineral supplementation procedures were described in the previous report. In yr1 the following subset of calves ING-AN = 10, ING-BN = 11, ORG-AN = 11, and ORG-BN = 11. To facilitate intensive calf blood sample collection, a week before the expected start of the calving season, the subset of cows for intensive sampling were maintained in two 2.0 ac experimental pastures (1 pasture per TM source) and continued to receive their assigned TM supplements at an equivalent rate and frequency as the groups from which they were selected. A group of trained individuals observed the cows every 30 min 24 h a day for signs of parturition. At parturition, calves born to the subset cows had blood samples collected at 0 h (prior to colostrum consumption and within an hour of birth), 12 h and 24 h after the 0 h sample collection, and at 30 d of age to determine serum TM (Co, Cu, Fe, Mn, Mo, Se, and Zn) and plasma Se content. After the 0 h sample collection, cows and their calves remained in their respective pastures for the 12 h, and 24 h sample collection. After the 24 h sample collection, subset cows and their calves were returned to their original treatment groups and pastures from which they were initially removed. Calves Florida Beef Research Report

60 and their dams were brought up from pastures to the working facilities for the 30 d of age sample collections. At 115 ± 2 d of age and at weaning (205 ± 2 d), liver biopsy and blood samples for TM analysis were collected from calves (n = 26, ING-AN = 6, ING-BN = 6, ORG-AN = 7, and ORG-BN = 7) that were pair-matched to the subset of cows that had liver and serum TM analysis conducted on them. In yr 2, a total of 24 calves (n = 6 calves per treatment) were selected based on age, pre-weaning BW, and had liver biopsy and serum samples collected at weaning for determination of TM status. Each year, all calves had birth and weaning weights recorded for measures of calf performance. The investigators did not observe any mineral consumption by the calves throughout the experiment, though it is possible that calves could have ingested some of the TM supplements. Year 1 calf 0, 12, and 24 h serum TM data analysis utilized repeated measures of PROC MIXED. The calf 115-d and weaning calf serum and liver TM data utilized repeated measures of PROC MIXED. The fixed effects for the 0 to 24 h and the 115-d and weaning analyses each included TM source, breed, time and their interactions. The yr 1 30 d calf data and yr 2 weaning TM data were each analyzed by PROC MIXED with main effects of TM source, breed and TM source breed. Pearson correlations between serum and liver TM concentrations used PROC CORR. Calf performance data for yr 1 and yr 2 were analyzed separately because the calves had been exposed to different durations of TM source supplementation during the pre-natal phase of development between yr 1 and 2. Calf performance analyses for each yr used PROC MIXED with main effects of TM source, breed and TM source breed. The yr 1 calf performance data was used to back calculate the number of days on TM source prior to calving based on TM start date and calving date. The subsequent number of days on TM was used as a covariate in the yr 1 calf performance analysis and considered significant when P Results Year 1 Calf Trace Mineral Status All detectable serum TM concentrations varied (P 0.02) with time with the exception of Co, (P = 0.60). The 0 to 24 h Co concentrations were not affected (P>0.15; overall mean = 0.39 ± 0.02 and ng/ml) by TM source, breed, time or any interactions. Concentrations of Cu (0.29 and 0.24 ± 0.01 µg/ml) and Mo (8.93 and 2.04 ± 0.46 ng/ml) were greater (P<0.01) at 24 h compared to their 0 h values, respectively. Serum Cu, Fe, Mo, and Zn concentrations were not affected (P>0.05) by TM source. The BN calves (0.27 ± 0.01 µg/ml) had greater (P<0.01) serum Cu concentrations than AN calves (0.23 ± 0.01 µg/ml) when pooled across the first 24 h after birth. Breed time affected (P<0.001) serum Fe and tended to affect (P = 0.07) serum Zn due to greater Fe but lesser Zn concentrations in AN (153 ± 8.6 µg/dl; 0.88 ± 0.07 µg/ml) compared to BN (97 ± 8.4 µg/dl; 1.13 ± 0.07 µg/ml) calves at birth, respectively. At 12 h and 24 h post colostrum consumption, serum Fe (mean = 49 and 62 ± 6.0 µg/dl) and Zn (mean = 0.41 and 0.47 ± 0.05 µg/ml) concentrations, respectively, had decreased compared to their 0 h concentrations and subsequently did not differ (P>0.05) by breed. The breed time effect resulted in overall greater (P<0.05) mean Fe (87 ± 5.9 µg/dl) and a tendency for lesser (P<0.10) mean Zn (0.56 ± 0.06 µg/ml) in AN compared to BN (70.06 ± 5.77 µg/dl; 0.70 ± 0.06 µg/ml, for Fe and Zn, respectively) calves when concentrations were pooled over the 24 h post birth. There was no effect (P>0.05) of breed on serum Mo or plasma Se. Selenium concentrations in both serum and plasma were greater (P<0.001) in ORG (57.47 and 149 ± 2.47 ng/ml) compared to ING (46.45 and 119 ± 2.53 ng/ml) calves when pooled across the 0 to 24 h sample times, respectively. Additionally, serum Se concentrations were greater in AN (54.69 ± 1.73 ng/ml) compared to BN (49.23 ± 1.69 ng/ml) calves, and tended to be affected (P = 0.10) by breed time, due to greater (P<0.05) concentrations in AN compared to BN calves at 12 and 24 h post-colostrum consumption (data not shown). Serum Se was not affected (P>0.05) by TM source breed time. Plasma Se concentrations were affected (P = 0.04, data not shown) by breed time, however, breeds did not differ (P>0.05) within any time point. Plasma Se was affected (P = 0.03, Figure 1) by TM source Florida Beef Research Report

61 breed time. The ING-AN and ING-BN calf plasma Se concentrations did not change post-colostrum, while ORG-AN had the greatest (P<0.05) concentrations at 12 h compared to all other treatments. No effect (P>0.05) of breed time occurred for serum Cu or Mo concentrations. There was no effect (P>0.05) of TM source breed or TM source time for plasma Se or serum Co, Cu, Fe, Mo, and Zn concentrations. Calf Mn concentrations for 0, 12, and 24 h were not reported as concentrations were undetectable in all calf serum at 0 h and at 24 h. At 12 h, Mn concentrations were undetectable in all but 3 male calves, (ING-AN = 1.40 ng/ml, ORG-AN = 3.90 ng/ml, and ORG-BN = 0.90 ng/ml). It is not clear why Mn concentrations were not detectable in calf serum at 0 to 24 h of age, however cow serum Mn concentrations at calving were also not detectable. At 30 d of age, serum Co concentrations were greater (P = 0.02) in ING (1.58 ± 0.31 ng/ml) compared to ORG (0.56 ± 0.30 ng/ml) calves, while both serum and plasma Se concentrations were greater (P<0.001) in ORG compared to ING calves. Serum Se concentrations were affected by breed (P = 0.05) with greater concentrations in AN (40.70 ± 1.17 ng/ml) compared to BN (37.36 ± 1.14 ng/ml) calves. No other effects (P 0.28) of TM source, breed, or interactions occurred for calf TM concentrations at 30 d of age. Calf d 30 TM concentration pooled means are presented in Table 1. At 115 d of age and weaning (205 d), calf serum concentrations of Co, Cu, Fe, Mn, Mo, and Zn were not affected (P>0.05), by TM source, but Se concentrations were greater (P<0.001) in ORG (29.78 ± 1.33 ng/ml) compared to ING (18.21 ± 0.88 ng/ml) calves. Additionally, AN calves had greater (P 0.03) serum Co and Se (0.83 ± 0.14 and ± 1.30 ng/ml) but lesser (P<0.01) Mo (2.52 ± 0.57 ng/ml) compared to BN (0.47 ± 0.08, ± 0.90, and 5.04 ± 0.57 ng/ml for Co, Se, and Mo, respectively) calves. Breed did not affect (P>0.05) serum Cu, Fe, Mn, or Zn concentrations. Serum Co and Zn concentrations were affected (P<0.001), by time as Co concentrations were greater (P<0.05) at weaning compared to d 115 concentrations, while Zn was greater (P<0.05) at d 115 compared to weaning. Serum Cu, Fe, Mn, Mo, and Se concentrations were not affected (P>0.05) by time. Serum Fe and Mn were affected (P<0.01) by TM source breed when concentrations were pooled across time. Greater (P<0.05) Fe and Mn were observed in ORG-BN (165 ± 13.6 µg/dl, 2.31 ± 0.19 ng/ml) compared to ING-BN (115 ± 10.3 µg/dl, 1.43 ± 0.21 ng/ml), but neither ING-AN (161 ± 14.3 µg/dl, 1.99 ± 0.21 ng/ml) nor ORG-AN (138 ± 11.4 µg/dl, 1.58 ± 0.19 ng/ml) differed (P>0.05) from each other for Fe and Mn, respectively. No effect (P>0.05) of TM source breed occurred for serum Co, Cu, Mo, Se, or Zn concentrations. Serum Fe was not affected (P>0.05) by TM source breed time, but exhibited (P<0.01) a breed time effect (data not shown). Angus calf Fe concentrations were decreased (P<0.05) at weaning compared to d 115 concentrations, while BN serum Fe concentrations did not differ (P>0.05) between d 115 and weaning. There was no breed time effect (P>0.05) for Co, Cu, Mn, Mo, Se, and Zn serum. Serum Se tended (P = 0.07) to be affected by TM source time, as ORG (29.39 and ± 1.61 ng/ml) concentrations were similar (P>0.05) on d 115 and weaning, while ING (19.58 and ± 0.99 ng/ml) concentrations were greater (P<0.05) at d 115 compared to their weaning concentrations. The effect of TM source breed time affected (P 0.05) serum Co, Mn, and Mo concentrations and tended (P 0.10) to affect serum Cu, Se, and Zn (Table 4-5). The greater (P<0.05) Mo concentrations in the ORG-BN calves compared to all other treatments resulted in a TM source day effect (P<0.01), as ORG calves had greater (P<0.05) Mo at weaning compared to ING calves, while Mo concentrations did not differ (P>0.05) between TM sources on d 115. There was no effect (P>0.05), of TM source time on Co, Cu, Fe, Mn, or Zn serum. Calf liver Co, Fe, Mn, Mo, Se, and Zn concentrations were affected (P 0.03) and Cu concentrations tended (P = 0.06) to be affected by time (Table 1). Liver Mn was affected (P = 0.01) by TM source breed, with greater Mn concentrations in the ORG-BN (10.58 ± 0.52 µg/g) calves compared to all other Florida Beef Research Report

62 treatments (ING-AN = 7.96 ± 0.56 µg/g, ING-BN = 7.63 ± 0.56 µg/g, and ORG-AN = 7.98 ± 0.52 µg/g). The greater concentrations in the ORG-BN calves resulted in greater (P 0.05) liver Mn in ORG (9.28 ± 0.37 µg/g) compared to ING (7.80 ± 0.40 µg/g) calves and in BN (9.11 ± 0.38 µg/g) compared to AN (7.97 ± 0.38 µg/g) calves. A TM source breed effect (P = 0.04) occurred for liver Se, as the ORG-AN (0.86 ± 0.08 µg/g) had greater (P<0.05) Se compared to all other treatments (ING-AN = 0.45 ING-BN = 0.56, and ORG-BN = 0.62 ± 0.08 µg/g), when Se concentrations were pooled across time. The greater ORG-AN liver Se resulted in greater (P 0.01) liver Se concentrations in ORG (0.74 ± 0.05 µg/g) compared to ING (0.50 ± 0.06 µg/g) calves, when values were pooled across time. No TM source or TM source breed effect (P>0.05) occurred for Co, Cu, Fe, Mo, or Zn liver concentrations. When concentrations were pooled across time, AN calves had greater (P 0.04) Co (0.20 ± 0.02 µg/g), Fe (568 ± 37.1 µg/g) and Zn (128 ± 3.8 µg/g) compared to BN calves (0.11 ± 0.02, 440 ± 28.8, and 117 ± 3.5 µg/g, for Co, Fe, and Zn, respectively). There was no breed effect (P>0.05) for liver Cu, Mo, or Se. There tended (P 0.10) to be a breed time effect for Co, due to greater (P<0.05) AN calf Co at weaning (0.27 and 0.12 ± 0.03 µg/g) compared to d 115, while BN Co did not differ (P>0.05) between d 115 (0.09 and 0.14 ± 0.03 µg/g) and weaning. Liver Mo tended to be affected (P = 0.09, data not shown) by breed time; however, AN and BN liver Mo concentrations did not differ (P>0.05) at d 115 or weaning. No breed time effect (P>0.05) occurred for liver Cu, Fe, Mn, Se, or Zn. Nor was there a TM source time effect (P>0.05) for Co, Cu, Fe, Mn, Mo, and Se. Liver Zn tended (P = 0.07) to be affected by TM source time. On d 115, ING (113.4 ± 5.2 µg/g) and ORG (118.4 ± 5.0 µg/g) liver Zn did not differ (P>0.05), but at weaning ING (137.8 ± 6.3 µg/g) Zn concentrations were greater (P<0.05) compared to ORG (117.2 ± 4.7 µg/g) calves. There was no effect (P>0.05) of TM source breed time on any liver TM concentrations. Serum and liver concentrations of Co (r = 0.88) and Se (r = 0.58) were the only calf TM that demonstrated (P>0.001) correlations. In yr 2, calf serum Co, Cu, Fe, Mn, Mo and Zn concentration were not affected (P>0.05) by TM source, breed or TM source breed. Mean values for Co, Mn, and Mo were 0.88 ± 0.15, 3.37 ± 0.27, and 3.65 ± 0.51 ng/ml, respectively. The mean values for Cu, Zn, and Fe were 0.62 and 0.85 ± 0.02 µg/ml, and 128 ± 6.7 µg/dl, respectively. However, serum Se was greater (P<0.001) in ORG (32.08 ± 1.23 ng/ml) and AN (29.25 ± 1.23 ng/ml) compared to ING (18.17 ± 1.23 ng/ml) and BN (21.00 ± 1.23 ng/ml) calves, respectively. Serum Se was also affected (P = 0.02) by TM source breed, as the ORG-AN (38.50 ± 1.74 ng/ml) and ORG-BN (25.67 ± 1.74 ng/ml) calves each differed (P<0.05) from the other 3 treatments, while ING-AN (20.00 ± 1.74 ng/ml) and ING-BN (16.33 ± 1.74 ng/ml) did not differ (P>0.05) from each other. The yr 2 liver TM concentrations are presented in Table 2. There was no TM source effect (P>0.05) for liver concentrations of Co, Cu, Fe, Mn, Mo, and Zn. Consistent with yr 1, liver Se concentrations were greater (P<0.001) in ORG compared to ING calves at weaning. Breed had no effect (P>0.05) on liver Cu, Fe, Se and Zn concentrations. The AN calves had greater (P = 0.02) Co, but lesser (P 0.02) Mn and Mo compared to BN calves. Liver Mn was also affected (P = 0.004) by TM source breed, as ING-BN (8.59 ± 0.33 µg/g) calves had greater (P 0.01) Mn compared to all other treatments (ING-AN = 6.46, ORG-AN = 7.28, and ORG-BN = 7.24 ± 0.33 µg/g) which did not differ (P>0.05) from one another. The was no TM source breed effect (P>0.05) for liver Co, Cu, Fe, Mo, Se, and Zn. While no correlations (P>0.05) between serum and liver values occurred for Cu, Mn, Mo, and Zn, there were strong positive correlations (P 0.002) between calf serum and liver concentrations for Co (r = 0.90), Fe (r = 0.60), and Se (r = 0.73). Year 1 and 2 Calf Performance Birth weight in yr 1 and yr 2, did not differ (P>0.05) by TM source, breed, or TM source breed (Table 3). In yr 1, ORG calves had greater (P 0.02) weaning weight (498 ± 5.9 kg), ADG (2.03 ± 0.02 lb/d), and 205-d adjusted weight (498 ± 5.9 lb) compared to ING calves (476 ± 5.9 lb, 0.88 ± 0.01 kg/d, 479 ± 5.9 lb, respectively). In yr 2 (Table 3), there was no effect (P>0.05) of TM source or TM source breed for any calf performance traits. However, BN calves had greater (P<0.001) weaning weight (476 ± 7.3 lb), Florida Beef Research Report

63 ADG (2.07 ± 0.02 lb/d), and 205-d adjusted weight (503 ± 6.6 lb), than AN calves (432 ± 7.3 lb, 1.81 ± 0.02 lb/d, 450 ± 6.6 lb, respectively). Plasma Se, ng/ml b b a a c b a a ING-AN ORG-AN ING-BN ORG-BN b b a a Calf age, h Figure 1. Angus (AN) and Brangus (BN) 0 to 24 h plasma Se concentrations in calves born to dams that were supplemented with inorganic (ING) or organic (ORG) trace mineral (TM) sources during gestation and lactation. TM source breed time, (P = 0.03). a-c Means with different superscripts differed within hour, (P<0.05) Florida Beef Research Report

64 Table 1. Effect of inorganic (ING) or organic (ORG) prenatal trace mineral supplementation on year 1 Angus (AN) and Brangus (BN) calf serum and liver trace mineral (TM) concentrations at 115 d of age and weaning (205 d) Serum 2 Liver, TM source Breed Item µg/g 1 ING-AN ING-BN ORG-AN ORG-BN Co ng/ml d a 0.53 x x d b 2.32 by 0.71 a 0.79 a 0.77 ay SEM Cu µg/ml d c d d SEM Fe µg/dl d b d a SEM Mn ng/ml d a 2.25 a, b 1.40 a 1.49 a 2.90 by d b x SEM Mo ng/ml d a 2.02 a 6.47 by 3.36 a 2.27 ax d b 2.57 a 1.77 ax 2.13 a 9.66 by SEM Se ng/ml d b d a SEM Zn µg/ml d a d b SEM Liver TM concentrations: time, (P 0.06); TM source time, (P>0.05); breed time, (P>0.05); TM source breed time, (P>0.05). 2 Serum TM concentrations: TM source breed time, (P 0.05) for Co, Mn, and Mo; TM source breed time, (P>0.05) for Cu, Fe, Se, and Zn. a, b Means with different superscripts differed by time for liver and within that time point for serum, (P 0.05). c, d Liver means with different superscripts differed by time, (P 0.10). x, y Serum means within treatment with different superscripts differed by time, (P<0.05) Florida Beef Research Report

65 Item 1 Table 2. Effects of inorganic (ING) and organic (ORG) trace mineral (TM) source supplementation on Angus (AN) and Brangus (BN) calf weaning liver (µg/g; on a DM basis) TM concentrations in year 2 ING ORG AN BN SEM TM source Breed Co b 0.13 a 0.02 Cu Fe Mn a 7.91 b 0.23 Mo a 2.68 b 0.15 Se 0.38 a 0.64 b Zn TM source breed, (P>0.10) for all TM except for Mn, (P = 0.004). a, b Main effect means within a row with different superscripts differed, (P<0.05). Table 3. Effect of inorganic (ING) and organic (ORG) trace mineral (TM) supplementation to gestating and lactating cows on calf performance in year 1 and year 2 TM source Breed (B) P-value Variable ING- ING- ORG- ORG- AN BN AN BN SEM TM B TM B Year 1 calves 1, n Birth BW, lb Weaning BW, lb ADG, lb/day d adj. BW, lb Year 2 calves, n Birth BW, lb Weaning BW, lb < ADG, lb/day < d adj. BW, lb < Number of days cows were on mineral prior to calving was used as a covariate Florida Beef Research Report

66 Florida Beef Research Report

67 Effects of Prenatal and Postnatal Trace Mineral Supplement Source and Breed on Beef Calf Acute Phase Response to Weaning D. Price 1, M. Hersom 1, J. Yelich 1, M. Irsik 2, O. Rae 2 Synopsis Trace mineral source supplied to dams did not affect calf weaning acute phase protein response in calves. Calf breed and sex were greater influencers to acute phase protein response at weaning. Summary Two experiments were conducted to evaluate two trace mineral (TM) sources provided to gestating and lactating Angus (AN) and Brangus (BN) cows and its subsequent effect on acute phase protein (APP) response in like breeds of calves at weaning during 2 yr. The TM supplement sources included inorganic (ING; Na selenite and salt sulfates) or organic (ORG; Se-yeast and proteinates) forms of Co, Cu, Mn, Se and Zn and were initiated 82 ± 2 d pre-calving until weaning in yr 1 and from conception to weaning in yr 2. In both years, calves (yr 1, n = 28/sex, 7/TM source breed of bulls, heifers, steers; yr 2, n = 48 heifers and 49 steers, 12 or 13/TM source breed), were separated from dams at weaning (d 0), maintained in dry-lot pens from d 0 to 7, and on bahiagrass pastures from d 7 to 14. Blood samples were collected from calves for analysis of acid soluble protein (ASP), ceruloplasmin and haptoglobin on d 0, 1, 3, 7, and 14 relative to weaning. At weaning, liver biopsies for TM status were collected from 26 calves in yr 1 (ING-AN = 6, ING-BN = 6, ORG-AN = 7, and ORG-BN = 7) and 24 calves in yr 2 (ING-AN = 6, ING-BN = 6, ORG-AN = 6, and ORG-BN = 6). All APP responses in yr 1 and 2 were not affected (P>0.05) by TM source, but were affected (P 0.05) by day. In yr 1, peak concentrations of all APP occurred on d 3. In yr 2, peak concentrations occurred on d 3 for ASP and haptoglobin and on d 7 for ceruloplasmin. Within a yr, ASP concentrations were greater (P 0.01) in BN (yr 1 = 83.4 ± 3.5; yr 2 = 84.9 ± 2.6 µg/ml) than AN (yr 1 = 68.0 ± 3.5; yr 2 = 61.8 ± 2.6 µg/ml) calves. Haptoglobin concentrations were greater (P 0.05) in yr 1 and yr 2 in AN (1.8 ± 0.1 units) than BN (1.5 ± 0.1 units) calves within each yr. Heifers had greater (P 0.05) ceruloplasmin concentrations (15.2 ± 0.5 mg/dl) than steers (13.6 ± 0.5 mg/dl) and bulls (12.9 ± 0.5 mg/dl) in yr 1. In yr 2, heifers (16.7 ± 0.4 mg/dl) had greater (P 0.05) ceruloplasmin concentrations than steers (15.5 ± 0.4 mg/dl). Liver Se concentrations were greater (P<0.05) in ORG than ING, and Co was greater (P<0.05) in AN than BN calves both years. Maternal TM source did not affect calf weaning APP response; whereas calf sex and breed affected the APP response in each of two years. Introduction Weaning is a stressful and an unavoidable aspect of cattle production. During stress, an animal s immune system is vital to protecting it from environmental insults it may encounter. The acute phase response (APR) is part of the non-specific innate immune system and along with neutrophils are part of an animal s first line of defense. The APR acts to restore homeostasis and involves a cascade of complex reactions, systemic physiological alterations, and changes in plasma proteins (Heinrich et al., 1990; Gruys et al., 2005). Trace minerals (TM) are essential to proper functioning of the immune system as deficiencies can reduce immune responses (Spears, 2000; Spears and Weiss, 2014). However, understanding of the interactions between calf breed and TM source on APP at weaning needs further clarification. Therefore, the objective of this study was to investigate the effects of pre-natal and post-natal TM source and cow breed on calf APR at weaning. Materials and Methods A 2 2 factorial design consisting of TM source (inorganic vs. organic) and breed (Angus vs. Brangus) was utilized over a 2-yr period to generate calves for experiments. In yr 1, gestating cows (Angus, AN = 99; Brangus, BN = 100) were blocked by gestation length, BW, BCS, and allocated randomly to receive Florida Beef Research Report

68 of 2 TM (Co, Cu, Mn, Se, and Zn) supplement sources 1) inorganic minerals (ING, n = 100, Na selenite and Co, Cu, Mn, and Zn as salt sulfates) or 2) organic minerals (ORG, n = 99) with Se-yeast (Sel-plex, Alltech, Nicholasville, KY) and Co, Cu, Mn, and Zn as proteinates (Bioplex, Alltech, Nicholasville, KY). This resulted in 4 treatments that consisted of ING-AN, ING-BN, ORG-AN, and ORG-BN. Both TM supplements were formulated to meet NRC requirements and were manufactured in either a single pellet or loose mineral batch by the Lakeland Nutrition Group (Lakeland, FL). The formulation of the ORG TM source was based upon the manufacturer s proprietary bioavailability of the minerals. In yr 1, TM supplementation was initiated at 82 ± 2 d prior to parturition and supplements were fed as a wheat middling based pellet, which was delivered at a rate of 1.0 lb 1,000 lb BW -1 cow -1 d -1. The supplement was divided equally and fed 3 times per week (Monday, Wednesday, and Friday) in feed bunks until the start of the breeding season. Thereafter, each TM source was offered as a loose mineral supplement on a free choice basis at a rate of 4 oz cow -1 day -1 until weaning. After weaning of calves in yr 1, pregnant cows remained on the same TM sources for yr 2 of the experiment (ING-AN = 41, ING- BN = 44, ORG-AN = 38, and ORG-BN = 38). In yr 2, cows received access to feed and water as described for yr 1. Cows were fed their respective TM supplement as a pellet from post-weaning through breeding and as a loose mineral from breeding to weaning, and the TM supplement was fed and delivered at an equivalent rate and frequency as described for yr 1 of the experiment. Trace mineral pellet component analysis was conducted by Dairy One (Ithaca, NY) and pooled means from yr 1 and yr 2 are presented in Table 1. Blood and Liver Sample Collection At weaning in yr 1, a total of 84 calves (213 ± 2 d of age) including bulls (n = 28, 7/treatment), heifers (n = 28, 7/treatment), and steers (n = 28, 7/treatment, castrated at 69 ± 3 d of age) had blood samples collected on d 0, 1, 3, 7, and 14 relative to weaning (d 0) for analysis of APP. Calves (n = 26) used for mineral analysis were also used for blood sample collection. The remaining calves (n = 58) were stratified within treatment by sex, age, and preweaning BW and randomly chosen until an equal number of calves of each gender were represented within each treatment. At weaning in yr 2, a total of 96 calves (203 ± 1 d of age) that included heifers (n = 48, 12/treatment) and steers (n = 49, ING-AN = 13 and 12 each for ING-BN, ORG-AN, and ORG-BN; castrated at birth) had blood samples collected on d 0, 1, 3, 7, and 14 relative to weaning (d 0) for analysis of APP. As in yr 1, calves (n = 24) used for mineral analysis were also used for blood sample collection. The remaining calves (n = 72) were stratified within treatment by sex, age, and preweaning BW and randomly chosen until an equal number of calves of each gender were represented within each treatment. To determine calf TM concentrations associated with weaning, blood samples and liver biopsy samples were collected the week prior to weaning from 26 calves (ING-AN = 6, ING-BN = 6, ORG-AN = 7, and ORG-BN = 7) in yr 1 and 24 calves (ING-AN = 6, ING-BN = 6, ORG-AN = 6, and ORG-BN = 6) calves per treatment) in yr 2. In yr 1, calves were pair matched with cows that had been selected within each treatment to determine liver and blood mineral concentrations across several stages of a cow s yearly production cycle. During both years, calves were maintained in 4 drylot pens (1 pen for each treatment) from weaning until d 7. In yr 1, calves were fed 0.88 lb 1000 lb BW -1 calf -1 d -1 of TM supplement and 1.61 lb calf -1 d -1 of a weaning pellet (chlortetracycline + sulfamethazine) on d 1, on d 2 the weaning pellet was increased to 3.2 lb calf -1 d -1. On d 3, 1.81 lb calf -1 d -1 of a 50:50 mix of corn gluten feed and soybean hulls were added to the TM supplement and weaning pellet and on d 7, a pellet containing monensin was added to the ration at 1.0 lb calf -1 d -1. Calves received the final ration formulation from d 7 to 14 of the experiment. In yr 2, starting on d 0 through d 7 calves were fed 0.88 lb 1000 lb BW -1 calf -1 d -1 of TM supplement, 3.5 lb calf -1 d -1 of a weaning pellet (chlortetracycline + sulfamethazine), and 1.3 lb lb calf -1 d -1 of a 50:50 mix of corn gluten feed and soybean hulls. Starting on d 7 calves received 1% of BW of the final ration formulation which included the TM supplement offered at 0.88 lb 1000 lb BW -1 calf -1 d -1, 3.20 lb of Florida Beef Research Report

69 weaning ration, and the balance of corn gluten feed and soybean hull mix. In both years, calves had ad libitum access to bermudagrass hay and water from d 0 to 7 of sample collection. Calves were also provided with adequate feed bunk space, water, and shade. On d 7 of sample collection, calves were sorted based on TM supplement source into two 2.5 ac pastures for the next 7 days in yr 1 and in yr 2. Subsequently, on d 14 calves were sorted based on weaning BW into twenty, 2.0 ac pastures (5 pastures/treatment) with 4 to 6 calves/pasture for the next 7 d in yr 1 and yr 2. APP, Liver, and Blood Mineral Analysis Plasma concentrations of ASP were analyzed in duplicate with a commercial colorimetric assay (Bicinchoninic Acid Protein Assay Kit; Sigma-Aldrich, St. Louis, MO) and modifications according to Nakajima et al., (1982). Plasma concentrations of haptoglobin were determined in duplicate samples by estimation of differences in peroxidase activity by a biochemical assay measuring haptoglobinhemoglobin complexing (Makimura and Suzuki, 1982). Plasma ceruloplasmin oxidase activity was determined in duplicate samples. A colorimetric assay utilized procedures by Demetriou et al. (1974). All TM analysis (Co, Cu, Fe, Mn, Mo, Se, and Zn) for serum and liver (dry matter basis) was conducted by a commercial laboratory (DCPAH, Michigan State University, Lansing, Michigan). Statistical Analysis Because calves were exposed to different durations of TM source during the pre-natal phase of development in yr 1 and 2, data from yr 1 and 2 were analyzed separately. Calf was the experimental unit in all analyses. In both years, calf BW, BW change, and ADG were analyzed with PROC MIXED, while APP data were analyzed as repeated measures using PROC MIXED in SAS (Statistical analysis System, SAS Institute Inc., version 9.4, Cary, NC). The models included main effects of TM source, breed, sex, day relative to weaning (APP data) and their interactions. When calf sex and interactions with sex were not significant, (P>0.05) calf sex was excluded from the model. The random statement included calf nested within treatment. Calf serum and liver TM data were analyzed within each year using PROC MIXED with the main effects of TM source, breed, and the interaction. The random statement included calf nested within TM source breed. Results are presented as LSMEANS ± SE. Differences between and within treatment means were identified by using PDIFF. Pearson correlations between ADG from d 0 to 14 and each APP were analyzed with PROC CORR. Statistical significance was declared at P 0.05 and a tendency was 0.05 < P Results Year 1 Calf Performance, APP, and TM Concentrations Calf sex and interactions with calf sex did not affect (P 0.10) any ADG value, so they were removed from the model. Weaning weight of calves did not differ (P = 0.72) between TM sources, however BN calves tended (P = 0.09) to be 16.5 lb heavier compared to AN calves. Calf d 0 to 7 ADG (Table 5-2) was greater (P = 0.01), in ORG (3.18 ± 0.42 lb/d) compared to ING (1.48 ± 0.42 lb/d) calves, and in BN (P<0.001, 4.37 ± 0.42 lb/d) compared to AN (0.26 ± 0.42 lb/d) calves. This resulted in the greater (P 0.01) BW change from d 0 to d 7 in both ORG and BN calves compared to ING and AN calves, respectively. There was no effect (P>0.05) of TM source breed on calf d 0 to 7 ADG or d 0 to 7 BW change. Conversely, d 7 to 14 ADG was negative for calves of both TM sources and both breeds. The ING (-1.57 ± 0.40 lb/d) calves lost less (P<0.001), BW/d compared to ORG (-3.81 ± 0.40 lb/d) calves, while AN (-0.74 ± 0.40 lb/d) calves lost less (P<0.001) BW/d compared to BN (-4.63 ± 0.40 lb/d) calves. There was no effect (P = 0.24) of TM source breed on d 7 to 14 ADG. Furthermore, calf ADG from d 0 to 14 did not differ by TM source (P = 0.26), breed (P = 0.66), nor TM source breed (P = 0.21). The mean ADG over the 14-d period was was lb/d. Calf BW on d 14 did not differ (P>0.05) by TM source or TM source breed, but BN (514 ± 6.6 lb) calves tended (P = 0.06) to weigh more compared to AN (494 ± 6.6 lb) calves. Sex also affected (P<0.001) d 14 BW as bulls (542 ± 8.8 lb) weighed more compared to heifers (492± 8.8 lb) and steers (478 ± 8 lb). The BW change from d 0 to d 14 did not differ (P>0.05) by TM source, breed, or TM source breed Florida Beef Research Report

70 There was a TM source breed day (Figure 1, P = 0.04) effect on ASP concentrations. On d 14, all treatments had ASP concentrations that did not differ (P>0.05) from their d 0 values. There was a tendency (P = 0.09) for a TM source day effect for ASP, as d 14 ASP concentrations of ING (79.8 ± 4.7 µg/ml) calves tended (P = 0.06) to be greater compared to ORG (67.0 ± 4.7 µg/ml) calves, but, ASP concentrations in ING and ORG calves did not differ (P 0.15) from their d 0 values. Pearson correlations between ADG from d 0 to 14 and calf yr 1 APP are presented in Table 3. Average ASP concentrations demonstrated (P<0.10, Table 3) low to moderate (r ranged from to -0.38) negative correlations with calf ADG in year 1. Haptoglobin values were affected a TM source breed day effect (Figure 2, P = 0.05) on haptoglobin values as ING-AN had greater (P 0.05) haptoglobin compared to all other treatments at weaning. On d 7, ORG-AN exhibited peak haptoglobin that tended (P 0.10) to differ from all other treatments which demonstrated peak values on d 3. On d 14, ORG-AN differed (P = 0.03) from ING-AN, but neither AN group differed (P>0.05) from ING-BN or ORG-BN. Importantly, d 14 haptoglobin values did not (P>0.05) differ from their d 0 values for ORG-AN, ING-BN, and ORG-BN and were less (P<0.01) than their d 0 haptoglobin values for ING-AN. Similar d 0 and d 14 values demonstrated calves recovered from the APR induced by weaning stress. Average haptoglobin values tended (P<0.10, Table 3) to be positively correlated (r = ranged from 0.27 to 0.39) with calf ADG from d 0 to 14. A TM source breed day effect (Figure 3, P = 0.04) occurred for plasma ceruloplasmin concentrations, as ING-BN calves displayed peak ceruloplasmin concentrations on d 7, while peak concentrations in all other treatments occurred on d 3. No definitive pattern in the ceruloplasmin response was evident despite the TM source breed day effect. There was no TM source breed, breed sex, TM source day, TM source breed sex, TM source sex day, breed sex day, and TM source breed sex day effects (P 0.10) on calf plasma ceruloplasmin concentrations. Average ceruloplasmin concentrations exhibited low to moderate negative relationship (r = ) with calf d 0 to 14 ADG (Table 3). There was no TM source breed effect (P>0.05) on calf serum Co, Fe, Mn, Se and Zn. There were no effects (P>0.05) of TM source or breed for serum Co, Cu, Fe, Mn, and Zn (Data not shown). The liver TM concentrations are presented in Table 4. Liver Co, Cu, Fe, Mn, and Mo were not affected (P>0.05) by TM source. All liver TM concentrations, with the exception of Cu (P = 0.07) were not affected (P>0.10) by TM source breed. The ORG-AN calves (136 ± 17.3 µg/g) had greater (P<0.05) Cu compared to ING-AN (81 ± 18.7 µg/g) and tended (P = 0.07) to have greater Cu compared to ORG-BN (89.6 ± 17.3 µg/g), while ING-BN (105 ± 18.7 µg/g) Cu concentrations did not (P>0.05) differ from any treatment. Concentrations of Se were greater (P<0.001) in ORG compared to ING calves. Conversely, ING calves tended (P = 0.06) toward greater liver Zn concentrations compared to ORG calves. Angus calves had greater (P = 0.04) Co and tended (P = 0.06) to have greater Fe compared to Brangus calves. However, Brangus calves tended (P = 0.08) to have greater Mo compared to Angus calves. There was no effect (P>0.05) of breed on liver Cu, Mn, Se and Zn concentrations of calves at weaning. Year 2 Calf Performance, APP, and TM Concentrations In yr 2, ADG from d 0 to 7 and d 0 to 14 were not affected (P 0.05) by calf sex or interactions with calf sex (P>0.05), therefore, it was removed from those models. There was no effect (P>0.05) of TM source or breed on d 0 to 7 ADG (Table 2). However, there was a TM source breed effect (P 0.05) on d 0 to 7 ADG and BW change from d 0 to d 7, which was due to lesser ADG in ORG-AN (P 0.05) compared to ORG-BN calves. The ADG from d 7 to 14 was greater (P<0.001) in ING (3.42 ± 0.24 lb/d) compared to ORG (1.81 ± 0.24 lb/d), and in BN (3.31 ± 0.24 lb/d) compared to AN (1.90 ± 0.24 lb/d) calves. Moreover, steers (2.95 ± 0.24 lb/d) had greater (P 0.05) ADG compared to heifers (2.25 ± 0.24 lb/d) from d 7 to 14. Calf ADG from d 0 to 14 was greater (P<0.001) in ING (0.46 ± 0.15 lb/d) compared to ORG (-0.37 ± 0.15 lb/d) and in BN (0.49 ± 0.15 lb/d) compared to AN (-0.40 ± 0.15 lb/d), such that ING and BN calves gained weight and ORG and AN calves lost weight. There was a TM source breed effect for ADG from d 0 to 14 that resulted from greater (P = 0.02) weight loss in ORG-AN calves compared to Florida Beef Research Report

71 all other treatments. Final d-14 BW did not differ (P = 0.98) by TM source (500 ± 6.6 lb), however, BN (529 ± 6.6 lb) calves weighed more (P<0.001) compared to AN (470 ± 6.6 lb) calves, and steers (509 ± 6.6 lb) weighed more (P = 0.05), compared to heifers (223 ± 3 kg). There was also a TM source breed effect (P = 0.03), as ORG-AN calves weighed less (P<0.05) compared to ING-BN and ORG-BN, both of which did not differ (P>0.05) from ING-AN calves. Plasma ASP concentrations were not affected (P>0.05) by TM source breed, TM source sex, breed sex, TM source day, sex day, TM source breed sex, or TM source breed day, in yr 2. The ORG calves demonstrated (P 0.05), moderate correlations between ADG and average (r = 0.31) ASP concentrations. No other correlations (P>0.10) between ASP concentrations and ADG were observed. Haptoglobin values were not affected (P>0.05) by TM source, calf sex, or any interactions. Values of haptoglobin were greater (P = 0.03) in AN (1.80 ± 0.08 units) compared to BN (1.55 ± 0.08 units) calves when pooled across days. Peak values of haptoglobin were detected (P<0.001) on d 3 (46 % increase compared to d 0) in all calves. The ADG from d 0 to 14 tended (P<0.10) to be correlated with average (r = -0.24) haptoglobin values in ORG calves. No other relationships were evident (P>0.05) between haptoglobin and ADG. Plasma ceruloplasmin concentrations did not differ (P = 0.93) by TM source, but were greater (P = 0.02) in AN (16.78 ± 0.40 mg/dl) compared to BN (15.40 ± 0.41 mg/dl) calves when pooled across days. Moreover, an effect (P = 0.02) of TM source breed occurred for ceruloplasmin as ING-AN (17.47 ± 0.57 mg/dl) had greater concentrations compared to ING-BN (14.77 ± 0.57 mg/dl), while ORG-AN (16.10 ± 0.56 mg/dl) and ORG BN (16.03 ± 0.57 mg/dl) were intermediate. Steer ADG from d 0 to 14 correlated (P = 0.05) with average (r = -0.28) ceruloplasmin concentrations. No other relationships (P>0.05) between calf ADG and ceruloplasmin were observed. In yr 2, calf serum Co, Cu, Fe, Mn, Mo, and Zn concentrations were not affected (P>0.05) by TM source, breed, or TM source breed. The yr 2 liver TM concentrations are presented in Table 4. There was no TM source effect (P>0.05) for liver concentrations of Co, Cu, Fe, Mn, Mo, and Zn. Similar to yr 1, liver Se concentrations were greater (P<0.001) in ORG compared to ING calves at weaning. Breed had no effect (P>0.05) on liver Cu, Fe, Se, and Zn concentrations. The AN calves had greater (P = 0.02) Co, but lesser (P 0.02) Mn and Mo compared to BN calves. Liver Mn was also affected (P = 0.004) by TM source breed, as ING-BN (8.59 ± 0.33 µg/g) calves had greater (P 0.01) Mn compared to ING-AN (6.46 ± 0.33 µg/g), ORG-AN (7.28 ± 0.33 µg/g), and ORG-BN (7.24 ± 0.33 µg/g), which did not differ from each other. The was no TM source breed effect for liver Co, Cu, Fe, Mo, Se, and Zn. Maternal TM source did not affect calf weaning APP response; whereas calf sex and breed affected the APP response in each of two years. Literature Cited Demetriou, J. A., et al Clinical chemistry. p Geary, T. W., et al Anim. Reprod. Sci. 168:1 9. Heinrich, P. C., et al Biochem. J. 265: Makimura, S., and N. Suzuki Jpn. J. Vet. Sci. 44: Nakajima, K., et al Jpn. J. Clin. Chem. 11: Spears, J. W Proc. Nutr. Soc. 59: Spears, J. W., and W. P. Weiss Prof. Anim. Sci. 30: Florida Beef Research Report

72 Table 1. Analysis of trace mineral supplements provided to gestating and lactating cows Trace Mineral Supplement 1,2 Component Inorganic Organic DM, % CP, % TDN, % Ca, % P, % Mg, % K, % Na, % S, % Co, PPM Cu, PPM I, PPM Fe, PPM Mn, PPM Mo, PPM Se, PPM Zn, PPM Vitamin A, IU/kg 3 14,337 14,332 Vitamin D 3, IU/kg 3 1,286 1,286 Vitamin E, IU/kg Analysis of feedstuffs was carried out at Dairy One, (Ithaca, NY) and is averaged across both years of the experiment. 2 Trace mineral supplements were formulated and manufactured as a pellet in a single batch by Lakeland Nutrition Group (Lakeland, FL) and provided to cows and calves at 0.4 kg 454 kg BW -1 cow (or calf) -1 d Formulation values Florida Beef Research Report

73 Table 2. Effect of inorganic (ING) or organic (ORG) trace mineral (TM) source provided to dams preparturition and during lactation and to calves post-weaning on Angus (AN) and Brangus (BN) calf performance in response to a weaning stressor TM source Breed (B) Item ING-AN ING-BN ORG-AN ORG-BN SEM TM P-value B TM B Year 1, n BW 1, kg Day Day < Day ADG 3, kg/d Day 0 to < Day 7 to < < Day 0 to Year 2, n BW, kg Day < Day a 492 b 454 a 520 c < Day a 520 b 461 a 540 b < ADG, kg Day 2 0 to a,b a,b a b Day 1 7 to < < Day 2 0 to b 0.62 b a 0.35 b 0.22 < < Differed by sex (P 0.05). 2 Sex was removed from model because sex and interactions with sex were not significant (P>0.05). a-c Means without common superscripts differed (P<0.05). Table 3. Year 1 pearson correlations between calf ADG from d 0 to 14 and weaning average acid soluble protein (ASP), ceruloplasmin, and haptoglobin values in Angus (AN) and Brangus (BN) calves that were supplemented with inorganic (ING) or organic (ORG) trace mineral sources All Item calves 1 ING ORG AN BN Heifers Steers Bulls ASP * Haptoglobin 0.27 * 0.33 * * * 0.39 * Ceruloplasmin * 1 All calves examined correlations pooled across treatments. * P P Florida Beef Research Report

74 Item 1 Table 4. Effects of inorganic (ING) and organic (ORG) trace mineral (TM) source on Angus (AN) and Brangus (BN) calf liver (µg/g) TM concentrations (on a DM basis) at weaning in year 1 and year 2 ING ORG AN BN SEM TM source Breed Year 1 Co b 0.14 a 0.03 Cu Fe y 391 x 36.2 Mn Mo x 2.78 y 0.17 Se 0.37 a 0.71 b Zn 139 y 122 x Year 2 Co b 0.13 a 0.02 Cu Fe Mn a 7.91 b 0.23 Mo a 2.68 b 0.15 Se 0.38 a 0.64 b Zn a, b Main effect means within a row with different superscripts differed, P<0.05. x, y Main effect means within a row with different superscripts differed, P< TM source breed, P>0.10 for all TM except Cu in yr 1, P = 0.07 and Mn in yr 2, P = Florida Beef Research Report

75 100 Acid Soluble Protein, mg/dl a a a a c a, b a, c b b a, b a c b, c a, b a b a, b a, b a a ING-AN ING-BN ORG-AN ORG-BN Day relative to weaning Figure 1. Year 1 plasma acid soluble protein concentrations in Angus (AN) and Brangus (BN) calves that received inorganic (ING) or organic (ORG) trace minerals (TM) over 14 d post-weaning. TM source breed day, (P = 0.04). a-c Means without common superscripts differed (P<0.05) within day. Each treatment s d 14 acid soluble protein concentrations did not differ (P>0.05) from their d 0 concentrations Florida Beef Research Report

76 ING-AN ORG-AN ING-BN ORG-BN Haptoglobin, units b a a a b a, b a, b a Day relative to weaning Figure 2. Year 1 plasma haptoglobin in Angus (AN) and Brangus (BN) calves that received inorganic (ING) or organic (ORG) trace mineral (TM) supplements over 14 d post-weaning. TM source breed day, (P = 0.05). a, b Means within a day without common superscripts differed, (P<0.05) Florida Beef Research Report

77 Ceruloplasmin, mg/dl ING-AN ORG-AN ING-BN ORG-BN Day relative to weaning Figure 3. Year 1 plasma ceruloplasmin concentrations in Angus (AN) and Brangus (BN) calves the received inorganic (ING) or organic (ORG) trace mineral (TM) supplements over 14 d post-weaning. TM source breed day, (P = 0.04) Florida Beef Research Report

78 Florida Beef Research Report

79 Effects of Prenatal and Postnatal Trace Mineral Supplement Source on Angus and Brangus Bull Growth, Performance, and Sexual Development D. Price 1, M. Hersom 1, J. Yelich 1, M. Irsik 2, O. Rae 2 Synopsis Source of trace mineral supplementation had minimal effects on bull performance, trace mineral status, and seminal parameters. However, supplementation of a limited population of sexually immature bulls with organic sources of trace mineral hastened the time it took bulls to reach sexually maturity. Summary A 2 2 factorial design was used to evaluate breed (Angus, AN vs. Brangus, BN) and prenatal/postnatal trace mineral source (inorganic, ING vs. organic, ORG) on bull growth, performance, and sexual development. Bulls (241 ± 2 d, 249 ± 4 kg, n = 32, 8 per TM breed) born to dams that were supplemented with either Co, Cu, Mn, Se, and Zn as ING (Na selenite or salt sulfates) or ORG (Se-yeast and proteinates) TM sources were stratified by sire, age, and weaning BW. Bull diet included cracked corn, cottonseed hulls, a protein pellet, wet brewer s grains, and TM supplement pellet (1.0 lb lb BW -1 d). Weekly BW, and bi-weekly semen collection, scrotal circumference (SC), and BCS (scale 1-9) were recorded. Serum and liver biopsies to determine TM status were collected every 56 d. At puberty, there was no effect (P>0.05) of TM source or breed except for sperm concentration which was greater (P 0.05) in BN (172.4 ± cells/ml) compared to AN (96.9 ± cells/ml) bulls. At sexual maturity, except for ADG which tended (P<0.10) to be greater in ING (1.25 ± 0.08 kg/d) compared to ORG (1.05 ± 0.08 kg/d) bulls and secondary abnormalities which were lesser (P<0.05) in BN (9.6 ± 1.67 %) compared to AN (15.0 ± 1.18 %) bulls; no effect (P>0.05) of TM source, breed or TM source breed occurred for performance or seminal traits. Liver and serum TM concentrations were not affected (P>0.05) by TM source. Mean liver Cu, Mn, and Se concentrations were greater (P 0.05) in BN compared to AN bulls, while mean liver Co, Fe, Mo, and Zn did not differ (P>0.05) by breed. Performance, serum and liver TM concentrations, and seminal traits were all affected (P<0.05) by day of the experiment. Age at puberty did not differ (P>0.05) by TM source, breed or TM source breed. Although not significant (P = 0.14), ORG bulls were numerically 41 d younger than ING bulls at sexual maturity. Bull TM source had minimal effects on pubertal parameters, but ORG TM supplementation may hasten the age bulls reach sexual maturity. Introduction The ability of a bull to successfully breed a herd of females impacts pregnancy rates and production. Utilization of yearling bulls over 2-yr-old bulls of comparable genetic merit reduces production costs and increases lifetime pregnancies per bull (Kasari et al., 1996). The development of strategies that produce earlier maturing bulls will aid the use of yearling bulls that can successfully pass a BSE. Nutrition plays a large role in bull growth and sexual development, as bull BW and BCS are reflective of bull age at puberty. The use of trace minerals (TM) may enhance bull growth and development, as deficiencies of Se and Zn can negatively affect spermatogenesis, resulting in errors in sperm production, development, maturation, motility, and morphology (Bedwal and Bahuguna, 1994); which ultimately reduce fertility. While the need for specific TM in sexual development is recognized, limited information exists on the effects of TM supplement source on parameters of growing bull sexual development. When supplemented with complexed organic forms of Co, Cu, Mn, and Zn, compared to sulfate forms, sexually mature beef bulls exhibited improved sperm motility (Rowe et al., 2014), while a similar study that used prepubertal Florida Beef Research Report

80 beef bulls observed bulls fed complexed TM reached puberty 15 d earlier compared to bulls on the sulfate source (Geary et al., 2016). Moreover, a greater percentage of normal sperm was reported by Arthington et al. (2002), in yearling beef bulls supplemented with Zn proteinate compared to a Zn sulfate source. Additionally, breed differences in TM absorption and utilization occur within Bos taurus cattle breeds (Littledike et al., 1995; Ward et al., 1995) and between Bos indicus and Bos taurus Bos indicus cattle that may impact TM metabolism (Dermauw et al., 2014). Therefore, the objective of the present experiment was to determine the effects of inorganic or organic prenatal and postnatal TM supplement source on Angus and Brangus bull growth, performance, body composition, and sexual development. Materials and Methods A 2 2 factorial design that consisted of TM source (inorganic, ING and organic, ORG,) and breed (Angus, AN and Brangus, BN) was utilized to generate bull calves for the following experiment. Gestating AN and BN cows were received 1 of 2 TM (Co, Cu, Mn, Se, and Zn) supplement sources 1) inorganic minerals (ING, Na selenite and Co, Cu, Mn, and Zn as salt sulfates) or 2) organic minerals (ORG) with Se-yeast (Sel-plex, Alltech, Nicholasville, KY) and Co, Cu, Mn, and Zn as proteinates (Bioplex, Alltech, Nicholasville, KY). This resulted in 4 treatments that consisted of ING-AN, ING-BN, ORG-AN, and ORG-BN. Cow TM supplementation is outlined in prior reports in this issue. After weaning, at total 32 prepubertal bulls (8 bulls per treatment) were randomly selected from each treatment and blocked by breed, maternal TM source, sire, and weaning BW to investigate the effect of prenatal and postweaning TM source on bull sexual development, TM status, performance, and body composition. Bulls were maintained in four pastures (1 per treatment) at the University of Florida Beef Teaching Unit in Gainesville, FL for the entire 196 d of the experiment. Bulls were pen fed daily in a feed bunk and had access to bermudagrass hay (Cynodon dactylon) and water ad libitum. Bull diets consisted of a TMR (fed at 1.1 to 2.6 % BW) that included cottonseed hulls, cracked corn, protein pellet, fat, and the TM supplement which was delivered in a wheat-middling pellet and fed at 0.90 to 0.10% of BW. Beginning on d 8 of the trial and continuing for 150 d, bulls received wet brewers grains in their TMR at a rate of 0.70 kg per kg of TMR. Bulls had BW recorded weekly, BCS recorded every 2 wk, and hip height (HH) recorded at 28-d intervals for determination of performance. Bull SC was measured with scrotal tape and recorded every 2 wk. Once a bull reached a SC of 26 cm, BSE were conducted at 2 wk intervals by a trained veterinarian which included measurements of BCS, SC, and semen collection by electroejaculation. Semen samples were used to quantify sperm motility and morphology, and concentration of sperm as determined by hemocytometer. To determine bull TM status, blood and liver biopsy (n = 16, four bulls per treatment) samples were collected for TM analysis at 56 d intervals from trial start through d 168. Blood for TM analysis was collected by caudal tail vein puncture. All mineral analysis for liver and serum (Co, Cu, Fe, Mn, Mo, Se, and Zn) was carried out at a commercial laboratory (DCPAH, Michigan State University, Lansing, Michigan) by procedures of Braselton et al. (1997). Data are presented on a DM basis. The PROC MIXED procedure was utilized for data at the start of the experiment, at the experimental endpoint (defined at the date of sexual maturity or the end of the experiment for those that didn t reach sexual maturity or puberty), and at the estimated date of puberty and sexual maturity with the main effects of TM source, breed, and their interaction. A repeated measures PROC MIXED analysis was used to analyze performance, and blood and liver TM concentrations with the main effects of TM source, day of trial, and their interaction. The random statement for all analyses included bull nested within TM source. Performance data was analyzed through d 168 of the experiment, as after that point too many bulls had left the trial for semen collection. A repeated measures PROC MIXED analysis was used to analyze SC, sperm concentration, motility, and morphology data with the fixed effects of TM source, day relative to puberty or maturity, and their interactions; where the day a bull reached puberty or sexual maturity was considered as d 0 for that particular bull. Bulls that did not reach puberty or sexual maturity during the Florida Beef Research Report

81 experiment, were excluded from the single time point and repeated measures puberty and sexual maturity data analysis. Pearson correlations between seminal traits and liver TM concentrations, and between serum and liver TM concentrations were analyzed with PROC CORR. Results are presented as LSMEANS ± SE. Differences between and within treatment means were identified by using PDIFF. Statistical significance was declared at P 0.05 and a tendency was 0.05 < P Results Twenty-seven out of the 32 bulls (ING-AN = 8, ING-BN = 6, ORG-AN = 8, and ORG-BN = 5) reached puberty during the trial, therefore, non-pubertal bulls were excluded from the analyses at puberty or adjusted for the day relative to puberty. Results at puberty are presented in Table 1. At puberty, there was no effect (P>0.05) of TM source on age at puberty, BW, BCS, SC, sperm concentration, motility or sperm morphology data; however, ADG was greater (P 0.05) in ING (2.56 ± 0.15 lb/d) compared to ORG (2.14 ± 0.15 lb/d) bulls. Sperm concentration was greater (P 0.05) in BN (172.4 ± cells/ml) compared to AN (96.7 ± cells/ml) bulls.. Breed had no effect (P>0.05) on BW, ADG, SC, gross and individual motility, and sperm morphology. At puberty, bull BW differed (P = 0.04) by TM source breed, where ING-BN tended (P<0.10) to weigh more than ING-AN, but did not differ (P>0.05) from ORG-BN or ORG-AN bulls. Additionally, ADG was affected (P = 0.04) by TM source breed, as ORG-BN had lesser (P<0.05) ADG compared to ING-BN and ORG-AN and tended (P<0.10) toward lesser ADG compared to ING-AN bulls. Bull SC was also affected by TM source breed (P = 0.01). The ING-BN bulls had greater (P<0.05) SC than either ORG treatment, but did not differ (P>0.05) from the ING-AN bulls. There was no TM source breed effect (P>0.05) on age, BCS, sperm concentration, motility, or morphology at puberty. During the experiment, 15 (ING-AN = 6, ING-BN = 2, ORG-AN = 4, and ORG-BN = 3) of the 32 bulls reached sexual maturity, therefore, 17 bulls were excluded from the analysis at sexual maturity and the analysis relative to the day of sexual maturity. Results at sexual maturity are presented in Table 2. At sexual maturity, there was no effect of TM source (P>0.05) or TM source breed (P>0.05) on age, BW, BCS, SC, or any sperm parameter measured. However, ING (2.75 ± 0.18 lb/d) bulls tended (P<0.10) toward a greater ADG compared to ORG (2.32 ± 0.15 lb/d) bulls at sexual maturity. Although, not statistically significant (P>0.05), the mean age at sexual maturity was 41 d earlier in ORG (351 ± 16 d) compared to ING (392 ± 16 d) bulls. The AN (15.0 ± 1.18 %) bulls had greater (P = 0.02) secondary abnormalities compared to BN (9.6 ± 1.67 %) bulls at sexual maturity; while breed did not affect (P>0.05) sperm concentration, age, BW, ADG, BCS, SC, motility, normal sperm, or primary abnormalities. Source of TM had no effect (P>0.05) on overall mean bull liver TM concentrations. Breed did not affect liver Co, Fe, Mo and Zn concentrations. However, when pooled across days, BN had greater (P 0.05) liver Cu (197 ±21.7 µg/g), Mn (8.81 ± 0.29 µg/g), and Se (1.32 ± 0.04 µg/g), compared to AN (129 ± 21.6, 7.77 ± 0.28, and 1.16 ± 0.04 µg/g, for Cu, Mn, and Se, respectively) bulls. There was no effect (P>0.05) of TM source breed, except for Mn (P = 0.05), where the ORG-BN (9.51 ± 0.42 µg/g) had greater (P<0.05) Mn compared to all other treatments (ING-AN = 7.94 ± 0.40 µg/g, ING-BN = 8.11 ± 0.39 µg/g, ORG-AN = 7.60 ± 0.40 µg/g) that did not differ (P>0.05) from one another. All liver TM were affected (P 0.02) by day, although Co showed no definitive trend. However, liver Cu, Mn, Mo, and Se increased, while liver Fe and Zn decreased by day of the trial. There was no effect (P>0.05) of TM source day on liver Cu, Fe, Mn, Mo, and Se concentrations. However, TM source day affected (P 0.01) liver Co and Zn concentrations. The ORG bulls had greater (P<0.05, Figure 1) liver Co on d 56 and 168 compared to ING bulls. Conversely, ING bulls had greater (P<0.05, Figure 2) liver Zn on d 0 compared to ORG bulls, but neither ING nor ORG bulls differed (P>0.05) on any other day. There was no effect (P>0.05) of breed day on liver Mn, Mo, and Zn concentrations. Liver Co was affected (P = 0.02) by breed day (Figure 1) due to greater (P<0.05) liver Co in AN (0.54 ± 0.04 µg/g) on d 0 compared to BN (0.34 ± 0.04 µg/g) bulls, although, the breeds did not differ (P>0.05) on subsequent days. Concentrations Florida Beef Research Report

82 of liver Cu were affected (P<0.01) by breed day, as AN and BN did not differ (P>0.05) on d 0 or 56, but on d 112 and 168, BN had greater (P 0.05) liver Cu compared to AN bulls (Figure 2). Liver Fe differed (P<0.01) by breed day (Figure 2), as BN (621 ± 36.7 µg/g) had greater (P>0.05) liver Fe on d 0 compared to AN (390 ± 36.7 µg/g) bulls, but did not differ (P>0.05) on subsequent days. Additionally, liver Se was affected by breed day due to a tendency for greater Se on d 56 and greater Se on d 168 in BN compared to AN bulls, (Figure 1). There was no TM source breed day effect (P>0.05) for liver Co, Cu, Se and Zn. However, liver Fe and Mn were affected (P 0.03) and Mo tended to be affected (P = 0.06) by TM source breed day, Table 7-7. Bull serum and liver TM concentrations were positively associated for Co, (P<0.001, r = 0.75) while weak negative associations were demonstrated for Cu (P = 0.07, r = -0.24), Fe (P 0.05, r = -0.26), and Zn (P = 0.02, r = -0.30). No relationships between serum and liver concentrations were observed (P<0.05) for Mn, Mo, and Se. Source of TM supplementation had minimal effects on bull performance, TM status, and seminal parameters. However, in our data set, supplementation of a limited population of sexually immature bulls with ORG sources of TM hastened the time it took bulls to reach sexually maturity; which would have reduced the age at which bulls were capable of successfully breeding females. Furthermore, breed influenced body composition, TM concentrations, and seminal parameters in relation to bull sexual development. Utilization of Bos indicus crossbreeding in regions that are deficient in TM, such as Florida, may be beneficial due to the increased ability of Bos indicus crossbred animals to metabolize and store Cu, Mn, and Se, compared to their Bos taurus counterparts. Additional research is needed to determine if breed differences for TM in seminal plasma and testicular tissue storage exist, which have the potential to influence seminal parameters and fertility Florida Beef Research Report

83 Table 1. Effect of inorganic (ING) or organic (ORG) prenatal and postnatal trace mineral (TM) supplement source on Angus (AN) and Brangus (BN) sexual parameters at puberty 1 and sexual maturity TM source Breed (B) P-value Item ING-AN ING-BN ORG-AN ORG-BN SEM TM B TM B Puberty, n Age, d BW, lb 730 x 856 y 842 xy 730 xy ADG, lb/d ab 2.71 a 2.44 a 1.83 b BCS SC, cm a 33.5 b 31.2 a 30.3 a Sperm concentration, 10 6 cells/ml Gross motility, % Individual motility, % Normal sperm, % Primary abnormalities, % Secondary abnormalities, % Sexual maturity, n Age, d BW, lb ADG 2, lb/d BCS SC 4, cm Sperm concentration, 10 6 cells/ml Gross motility 5, % Individual motility, % Normal sperm, % Primary abnormalities, % Secondary abnormalities, % Puberty was defined as the date at which the bull s ejaculate with a sperm concentration cells/ml and 10% motility. 2 ADG was calculated based on difference from d 0 and when bull reached puberty. 3 SC = scrotal circumference. 4 Gross motility was measured on scale of 0 to 4, (0 = none, 1 = poor, 2 = fair, 3 = good, and 4 = very good). a, b Row means with different superscripts differed, (P 0.05). x, y Row means with different superscripts differed, (P 0.10) Florida Beef Research Report

84 Liver Concentration, µg/g ING Co ORG Co AN Co BN Co AN Se BN Se * * * Day of experiment * Figure 1. Liver Co and Se concentrations in Angus (AN) and Brangus (BN) bulls supplemented prenatally and postnatally with inorganic (ING) or organic (ORG) sources of trace minerals (TM). Breed day for Co, (P<0.01). TM source day for Co, (P = 0.01). Breed day for Se, (P 0.05). * TM source and/or breed means differed within day, (P<0.05). Liver concenrtation, µg/g * * * AN Cu AN Fe ING Zn * BN Cu BN Fe ORG Zn Day of experiment Figure 2. Liver Cu, Fe, and Zn concentrations in Angus (AN) and Brangus (BN) bulls supplemented prenatally and postnatally with inorganic (ING) or organic (ORG) sources of trace minerals (TM). Breed day for Cu (P<0.01). Breed day for Fe, (P<0.01). TM source day for Zn, (P<0.01). * TM source and/or breed means differed within day, (P<0.05) Florida Beef Research Report

85 Impact of Estrus Synchronization and Fixed-time Artificial Insemination on Calving Distribution in Bos Indicus Influenced Beef Heifers N. Oosthuizen 1, P. L. P. Fontes 1, C. D. Sanford 1, F. M. Ciriaco 1, D. D. Henry 1, L. B. Canal 1, N. DiLorenzo 1, and G. C. Lamb 2 Synopsis The use of estrus synchronization and fixed-time artificial insemination increased the percentage of heifers that conceived in the first 19 d of the breeding season, and therefore, potentially altered the calving distribution by ensuring that more heifers calve early during the subsequent calving season. Summary A total of 751 Bos taurus Bos indicus beef heifers were enrolled in a completely randomized design at 2 locations from January to May of Within location, all heifers were randomly assigned to 1 of 2 treatments: 1) SYNCH (n = 371); heifers were exposed to the 5-d CO-Synch + controlled internal drug releasing (CIDR) protocol where they were treated with 100 µg of gonadotropin-releasing hormone (GnRH), 25 mg of prostaglandin F 2α (PGF 2α), and a CIDR insert on d 0; heifers received 50 mg of PGF 2α at CIDR removal on d 5, and were treated with 100 µg of GnRH and TAI 66 ± 2 h later on d 8; or 2) CONTROL (n = 380); heifers were exposed to natural service without estrous synchronization (ES) or fixed-time artificial insemination (TAI). On d 9, all heifers were exposed to bulls for the remainder of the breeding season at each location. Blood samples were collected on d -9 and on d 0 to determine pretreatment estrous cyclicity (progesterone 1.0 ng/ml). Pregnancy was diagnosed via transrectal ultrasonography 54 d after TAI by determining the presence of a viable fetus. Fetal age was estimated based on fetal size and structural features at the time of pregnancy diagnosis. Pregnancy rates on d 54 differed (P<0.001) between locations, but did not differ (P = 0.78) between CONTROL and SYNCH treatments. Pregnancy rates on d 54 were greater (P<0.001) in cycling compared with non-cycling heifers (63.9 vs 42.4%). A greater (P<0.05) proportion of SYNCH heifers became pregnant in the first 19 d of the breeding season compared with CONTROL heifers (52.2 vs 46.4%). Overall breeding season pregnancy rates did not differ (P = 0.98) between treatments. Introduction Reproductive efficiency is the most vital factor impacting the economics of a cow-calf operation (Smith et al., 2005). Reproductive management technologies such as ES and TAI can be utilized to increase reproductive efficiency and thus, profitability of beef cattle production systems. Estrus synchronization is a biotechnology that has been available for use in the cattle industry for more than 40 years. When ES is utilized, a greater proportion of cows and heifers may become pregnant earlier in the breeding season, and as a result, a greater proportion of calves may be born earlier in the calving season, and a calf crop with greater uniformity can be achieved (Dziuk and Bellows, 1983). With a more uniform calf crop, calves may be older and heavier at the time of marketing, resulting in a net increase in profit (Rodgers et al., 2012). Cow-calf production is an essential agricultural practice in the state of Florida, and with a subtropical climate, Florida is an ideal location for raising Bos indicus cattle. Differences in reproductive physiology exist between Bos indicus and Bos taurus cattle, which should be considered when establishing reproductive management programs (Figueiredo et al., 1997; Bó et al., 2003; Sartori and Barros, 2011). Numerous studies have been performed on calving distribution in Bos taurus cattle (Minick Bormann and 1 North Florida Research and Education Center, University of Florida, Marianna, FL 2 Department of Animal Science, Texas A&M University, College Station, TX Florida Beef Research Report

86 Wilson, 2010; Funston et al., 2012; Cushman et al., 2013); however, studies on calving distribution in Bos indicus cattle are currently lacking. Therefore, the current study was performed to evaluate the impact of ES and TAI on calving distribution in Bos indicus influenced beef heifers. We hypothesized that the use of ES and TAI would increase the proportion of heifers that calve at the beginning of the calving season by increasing the proportion of heifers pregnant in the beginning of the breeding season. Materials and Methods A total of 751 Bos indicus influenced beef heifers were enrolled in a completely randomized design at 2 locations (FL-1 and FL-2) in Florida. Within location, heifers were randomly assigned to receive one of two treatments: 1) 100 µg of GnRH, 25 mg of PGF 2α, and a CIDR (1.38 g of progesterone) insert (d 0), 50 mg of PGF 2α at CIDR removal (d 5), followed by treatment with 100 µg of GnRH and TAI 66 ± 2 h later (d 8) (SYNCH; n = 371); or 2) heifers were exposed to natural service without any ES or TAI (CONTROL; n = 380). Heifers in both the CONTROL and SYNCH treatments were exposed to bulls, beginning the day after TAI (d 9), for the entire duration of the breeding season. Artificial insemination technicians were distributed evenly within location. Blood samples were collected on d -9 and again on d 0, to determine the pretreatment cyclicity status of 564 heifers across both locations. Concentrations of plasma progesterone were determined with an immunoassay system (Immulite 1000 Version 5.22; Siemens Healthcare Diagnostics, Malvern, PA). Heifers were considered estrous cycling if concentrations of progesterone were 1.0 ng/ml in 1 or both blood samples before treatment initiation. Transrectal ultrasonography (Ibex portable ultrasound 5.0-MHz linear multi-frequency transducer, Ibex, E.I. Medical Imaging, Loveland, CO) was performed on d 54 after TAI to determine the presence of a viable fetus, thereby determining pregnancy status. Approximate fetal ages were determined at the time of pregnancy diagnosis on d 54. Fetal age was estimated based on fetal size and structural features present at the time of pregnancy diagnosis. Final pregnancy rates were determined by transrectal ultrasonography at least 30 d after the end of the breeding season. Cyclicity, fetal age, 54 d pregnancy rates, and final pregnancy rates were analyzed using the GLIMMIX procedure of SAS (version 9.4; SAS/STAT, SAS Inst. Inc., Cary, NC, USA). The first model accounted for the fixed effects of treatment, location, and treatment by location interaction. Since a majority (98%) of heifers were determined to be cycling at the FL-2 location, this location was excluded from the analysis assessing the effects of estrous cyclicity on treatments. A second model included the fixed effects of treatment, estrous cyclicity status (prepubertal or pubertal), and the treatment by estrous cyclicity interaction. The LIFETEST procedure of SAS was used to analyze survival estimates. Heifer was considered the experimental unit. Results Estrous cyclicity status differed (P<0.001) at the initiation of the treatment between locations and was greater at FL-2 than FL-1 (98.0 vs. 71.1%, respectively); however, cyclicity status did not differ (P>0.31) between respective CONTROL and SYNCH treatments (76.4 vs. 79.9%). No differences (P = 0.78) in pregnancy rates were noted between SYNCH and CONTROL treatments (65.5 vs. 64.5%). Pregnancy rates at d 54, based on heifers in which cyclicity was determined, did not differ (P = 0.18) between SYNCH and CONTROL treatments (56.7 vs. 49.9%); however, heifers that had attained puberty before the initiation of the treatments had greater (P<0.001) pregnancy rates than those that were non-cycling (64.1 vs. 42.6%), regardless of treatment. Pregnancy rates were not different Florida Beef Research Report

87 (P = 0.18) between cycling heifers in both SYNCH and CONTROL treatments (67.2 vs. 60.9%), and did not differ (P = 0.41) between non-cycling heifers in the SYNCH and CONTROL treatments (46.2 vs. 38.9%). No treatment by cyclicity interaction was observed (P = 0.92). Pregnancy rates at location FL-1 were poorer (P<0.001) than at location FL-2 (50.0 vs. 80.0%). No treatment by location interaction was observed (P = 0.47). Final overall pregnancy rates were determined after the conclusion of the breeding season. No difference (P = 0.98) was detected between SYNCH and CONTROL treatments (92.9 vs. 92.9%); however, final pregnancy rates differed (P = 0.003) between locations. A treatment by location interaction (P = 0.04) was observed, where location FL-1 had a greater average day of conception in the CONTROL treatment compared to the SYNCH treatment (d 32.6 ± 1.3 vs ± 1.3, respectively), whereas at location FL-2 no difference (P = 0.37) in day of conception was detected between CONTROL and SYNCH treatments (d 16.0 ± 2.2 vs ± 2.3). There was an effect of cyclicity on the mean day of conception, with a lower (P = 0.005) average day of conception in the cycling heifers compared to the non-cycling heifers (d 25.2 ± 1.1 vs ± 2.1). Using survival analysis, it was determined that the percentage of heifers that were pregnant during the first 19 d of the breeding season was greater (P<0.05) for the SYNCH treatment compared with the CONTROL (52.2 vs. 46.4%; Figure 2). After d 19 of the breeding season, no differences (P>0.05) were observed in the percentages of heifers that were pregnant at a specific interval during the breeding season. Acknowledgements The authors would like to thank Zoetis Animal Health (Parsippany, NJ) for their donation of PGF 2α (Lutalyse), GnRH (Factrel), and CIDR inserts (EAZI-BREED CIDR). The authors would also like to thank Deseret Cattle and Citrus (St. Cloud, FL), and Kempfer Cattle Co. (St. Cloud, FL) for providing heifers and labor for the implementation of the study. Literature Cited Bó, G. A. et al Anim. Reprod. Sci. 78: Cushman, R. A. et al J. Anim. Sci. 91: Dziuk P.J., and Bellows R. A J. Chem. Inf. Model. 57: Figueiredo, R. A. et al Theriogenology. 47: Funston, R. N. et al J. Anim. Sci. 90: Minick Bormann, J., and Wilson D. E J. Anim. Sci. 88: Rodgers, J. C. et al J. Anim. Sci. 90: Sartori, R., and Barros C. M Anim. Reprod. Sci. 124: Smith, M. F In: Applied Reproductive Strategies in Beef Cattle. p Florida Beef Research Report

88 Table 1. The effects of ES and TAI on pregnancy rates and the day of conception in SYNCH and CONTROL heifers Treatment a Item SYNCH CONTROL Average P-value b Heifers, no. FL FL Cyclicity c, % d pregnancy rate d, % Cycling Non-cycling Overall d pregnancy rate, % FL FL Overall Day of conception e, d FL FL Overall Final pregnancy rates f, % FL FL Overall a SYNCH: treated with 100 µg of gonadotropin-releasing hormone (GnRH), 25 mg of prostaglandin F 2α (PGF 2α) and a controlled internal drug releasing (CIDR) insert (d 0), 50 mg of PGF 2α at CIDR removal (d 5), followed by treatment with 100 µg of GnRH and fixed-time artificial insemination (TAI) 66 ± 2 h later. CONTROL: heifers were exposed to natural service without any estrus synchronization (ES) or TAI. All heifers were exposed to bulls, beginning the day after TAI (d 9), for the entire duration of the breeding season. b P-value is associated with the difference between SYNCH and CONTROL treatments. c Blood samples were collected via caudal venipuncture on d -9 and again on d 0 to determine pretreatment cyclicity status. Cyclicity was determined in 564 of the 751 heifers. d Pregnancy diagnosis was performed on d 54 after TAI. e The average day of conception was determined by estimating fetal age at the time of pregnancy diagnosis on d 54 after TAI and based on approximate day of conception from the first day of the breeding season. Percentages are reported as Least Square Means. f Final pregnancy rates were determined at least 30 d after the end of the breeding season Florida Beef Research Report

89 Effects of Bismuth Subsalicylate and Calcium-Ammonium Nitrate on Liver Mineral Concentration and Performance of Growing Beef Heifers D. D. Henry 1, F. M. Ciriaco 1, P. L. P. Fontes 1, N. Oosthuizen 1, C. D. Sanford 1, T. M. Schulmeister 1, and N. DiLorenzo 1 Synopsis Beef cattle production in the southeastern U.S. relies heavily on the use of forages which require supplementation of a source of non-protein nitrogen, such as urea. Nitrate has the potential to replace urea while reducing enteric CH 4 production of beef cattle. Bismuth subsalicylate may inhibit negative effects of high-s forages, such as the negative effects of S on trace mineral absorption. Summary A study was designed to evaluate the effects of bismuth subsalicylate (BSS) and encapsulated calciumammonium nitrate (ecan) on liver mineral concentration and performance of growing beef heifers consuming bahiagrass hay with supplemental molasses. Heifers were held in 25 pastures and each pasture was randomly assigned one of five treatments: bahiagrass hay and 3 lb of molasses (as is) per heifer (NCTRL); NCTRL oz of urea per lb of body weight (BW; U); NCTRL oz of nitrate per lb of BW (NIT); U oz of BSS per lb of BW (UB); and NIT oz of BSS per lb of BW (NITB). Liver biopsies and carcass ultrasound data were collected pre-treatment and after 70 d of treatment. Body weight of the heifers was recorded every 2 weeks throughout the experiment. There were no effects (P>0.05) of BSS or ecan on average daily gain (ADG) of growing beef heifers. Ribeye area was not affected (P>0.05) by the addition of BSS or ecan. An interaction between BSS and the source of non-protein nitrogen (NPN) was observed (P<0.01) for back fat thickness. The addition of BSS reduced (P<0.01) the concentration of Cu in the liver of heifers while increasing (P<0.01) Fe concentration. No effects (P>0.05) of ecan were observed for liver mineral concentrations. Providing BSS and ecan did not improve performance of growing heifers consuming bahiagrass hay and supplemental molasses; however, BSS did decrease the concentration of Cu in the liver. Introduction There is a growing desire to reduce the environmental impacts of beef production. One methodology that has been rigorously evaluated and reported is the addition of nitrate to the diets of cattle in place of traditional urea (van Zijderveld et al., 2011; Newbold et al., 2014; Hegarty et al., 2016). Most data indicate that nitrate can reduce enteric CH 4 production by 10 to 30% (Lee and Beauchemin, 2014; Guyader et al., 2015). Enteric CH 4 production can account for 2 to 12% of GE losses, depending upon diet type, and it has been theorized that nitrate may increase ME supply by reducing the amount of C lost as CH 4; however, most research has focused on the performance of cattle consuming moderate- (Lee et al., 2017b) to high-concentrate (Newbold et al., 2014) diets. Little is known about the effects of BSS on ruminant animals. For decades, BSS has been heralded as a mediator of H 2S in humans, lessening pain in the gastro-intestinal tract (Suarez et al., 1998; Levitt et al., 2002; Mitsui et al., 2003). In vitro ruminal fermentation has been used to evaluate the possible influence of BSS on in vivo parameters, but in vivo data is needed to truly evaluate to potential impacts on production and performance of cattle (Ruiz-Moreno et al., 2015). Bismuth compounds may have a place in beef production by mitigating the negative effects of S on trace mineral absorption. By binding to S (Suarez et al., 1998), BSS may reduce thiol- compounds which inhibit trace mineral absorption. The current experiment was designed to test the hypothesis that ecan would not impact performance of growing heifers consuming a bahiagrass hay and molasses diet. The second hypothesis was that BSS would not alter performance of growing heifers; however, liver trace mineral content should be increased Florida Beef Research Report

90 The objective of this experiment was to evaluate the performance and liver mineral concentration of heifers provided ecan and/or BSS. Materials and Methods Seventy-five growing Bos taurus and Bos indicus heifers (615 ± 126 lb of initial BW) were used in an incomplete randomized complete block design with a factorial arrangement of treatments at the University of Florida North Florida Research and Education Center Beef Unit in Marianna, FL. The experiment consisted of a 28 d adaptation period followed by a 56 d data collection period in which heifers were weighed every 14 d from d 0 to d 56. On d -28 and -27, all heifers were weighed and the average weight of each heifer on those 2 d was considered initial BW. Similarly, the average BW of each heifer on d 55 and 56 was considered final BW. On d -27, heifers were stratified and blocked by weight and allotted to 25 dormant bahiagrass (Paspalum notatum) pastures. Pastures (3.3 ac each) were located in 3 different areas of the Beef Unit and were within 0.32 miles of each other. The three locations were termed North Circle (n = 13), South Circle (n = 6), and R-Pens (n = 6). Pastures were stratified by location and randomly assigned to 1 of 5 treatments: 1) NCTRL, no added NPN or BSS; 2) U, urea supplemented at oz per lb of BW; 3) NIT, nitrate, in the form of ecan, supplemented at oz per lb of BW; 4) UB, urea supplemented at oz per lb of BW and BSS supplemented at oz per lb of BW; and 5) NITB, nitrate, in the form of ecan, supplemented at oz per lb of BW and BSS supplemented at oz per lb of BW. Treatments U, NIT, UB, and NITB were isonitrogenous. Heifers had ad libitum access to bahiagrass hay and received 3 lb/d (as is) of sugar cane molasses (Table 1). This experiment began on February 15, 2017 and prior to initiation, pastures were mob grazed to remove any residual forage; therefore, bahiagrass hay was the only forage available to the heifers. Molasses was weighed and provided daily, and was used as the carrier of treatments. Heifers BW was recorded every 14 d starting on d 0. To calculate ADG, difference in BW was divided by the number of d between BW recordings. Liver samples were taken on d -28 and -27, and again on d 55 and 56. A random subset of heifers (2 heifers/pen) was selected to collect liver tissue. One heifer per pen was randomly selected to have liver sample taken on d -28 and 55, and the second heifer donating liver tissue was collected on d -27 and 56. On d -28, -27, 55, and 56, carcass measurements were taken using ultrasonography. Ultrasonography measurements were made between the 12 th and 13 th intercostal space. Images were used to assess LM area and back fat thickness. Data were analyzed as a randomized complete block design with a factorial arrangement of treatments using pasture as the experimental unit. The model included the fixed effect of treatment and the random effects of block and location (North Circle, South Circle, and R-Pens). Initial liver mineral concentration and ultrasound measurements were used as covariates for final liver mineral concentration and ultrasound measurements, respectively. The following contrasts were used to aid in the interpretation of data: the effect of NPN = NCTRL vs. the mean of U, NIT, UB, and NITB; the effect of NPN source = the mean of U and UB vs. the mean of NIT and NITB; the effect of BSS = the mean of U and NIT vs. the mean of UB and NITB; and ecan BSS = the mean of U and NITB vs. the mean of NIT and UB. Significance was declared at P Results Growth performance data can be found in Table 2. At the beginning of the experiment, all treatments had similar BW (P>0.05). By the end of the experiment, BW was not affected by NPN (P = 0.47), source of NPN (P = 0.38), or BSS (P = 0.60); however, there was an interaction (P = 0.05) between BSS inclusion and source of NPN. There was no effect of NPN, ecan, BSS or an interaction for ADG measured within any time points (P>0.05) Florida Beef Research Report

91 Carcass ultrasound results are presented in Table 3. There was no effect of NPN, source of NPN, or BSS on ribeye area (P>0.05). A BSS NPN source interaction (P<0.01) was observed for back fat thickness on d 56 and change in fat thickness from d -28 to d 56. The concentration of trace minerals in the liver from cattle in the current experiment can be found in Table 4. Concentration of minerals in the liver were not affected by ecan (P>0.05). There were no interactions between BSS and source of NPN (P>0.05) affecting liver mineral concentration. The addition of NPN increased liver concentrations of Fe (P = 0.01) and Mn (P = 0.01) by 37 and 15%, respectively. Liver mineral concentrations of Cu were reduced (P<0.01) by 70% when BSS was provided to heifers consuming bahiagrass hay and molasses. The inclusion of BSS in the diets of heifers was also associated with a 30% increase (P = 0.02) in liver concentration of Fe. In conclusion, the inclusion of ecan did not improve nor worsen performance of growing heifers unless it was provided in combination with BSS. Alone, BSS did not decrease performance of heifers consuming bahiagrass hay and molasses. The diet in the current experiment contained approximately 0.5% S (DM) which may not have been great enough to truly observe the potential benefits of BSS on performance. Regardless of performance, heifers consuming BSS exhibited reductions in liver Cu and liver Fe accumulation, which may have detrimental effects in the long term. More research is required to determine the effects of BSS on cattle consuming diets of differing composition and S content. Acknowledgements The authors would like to thank the USDA for providing funding for this experiment. Literature Cited Guyader et al J. Anim. Sci. 93:3564. Hegarty et al J. Anim. Sci. 94:5372. Lee and Beauchemin Can. J. Anim. Sci. 94:557. Lee et al J. Anim. Sci. 95:3700. Levitt et al J. Appl. Physiol. 92:1655. Mitsui et al Clin. Chim. Acta. 335:131. Newbold et al J. Anim. Sci. 92:5032. Ruiz-Moreno et al J. Anim. Sci. 92:5032. Suarez et al Gastroenterology. 114:923. van Zijderveld et al J. Dairy Sci. 94: Florida Beef Research Report

92 Table 1. Analyzed chemical composition of bahiagrass hay and sugar cane molasses 1. Item Bahiagrass hay Sugar cane molasses DM, % OM, % DM CP, % DM NDF, % DM ADF, % DM TDN, % DM S, % DM Nitrate, % DM Analyzed by a commercial laboratory using a wet chemistry package (Dairy One, Ithaca, NY). Table 2. Effect of BSS 1 and ecan 2 on growth performance of beef heifers Treatment 3 P-value 4 Item NCTRL U NIT UB NITB SEM 5 NPN - NO 3 B B N Initial BW 6, lb Final BW 7, lb ADG, lb/d d -28 to d 0 to d 0 to d 0 to d 0 to BSS = bismuth subsalicylate. 2 ecan = encapsulated calcium-ammonium nitrate (5Ca(NO 3) 2-NH 4NO 3) 65.1% nitrate DM basis 3 NCTRL = ad libitum bahiagrass hay g/kg of BW of molasses (basal diet); U = basal diet mg/kg of BW of urea; NIT = basal diet mg/kg of BW of NO 3- ; UB = U mg/kg of BW of BSS; NITB = NIT mg/kg of BW of BSS. 4 - Observed significance levels for: NPN = effect of NPN, NCTRL vs the mean of U + NIT + UB + NITB; NO 3 = effect of ecan (excludes NCTRL); B = effect of BSS (excludes NCTRL); B N = interaction of BSS and ecan. 5 NCTRL, U, NIT, UB, and NITB had 5, 5, 5, 5, and 4 experimental units, respectively; largest SEM was provided. 6 Initial BW was the average of BW recorded on d -28 and Final BW was the average of BW recorded on d 55 and Florida Beef Research Report

93 Table 3. Effect of BSS 1 and ecan 2 on carcass ultrasound measurements. Treatment 3 P-value 4 Item 6 NCTRL U NIT UB NITB SEM 5 NPN - NO 3 B B N Ribeye area, cm Ribeye area change 7, cm Back fat thickness, cm <0.001 Back fat thickness change 8, cm < BSS = bismuth subsalicylate. 2 ecan = encapsulated calcium-ammonium nitrate (5Ca(NO 3) 2-NH 4NO 3) 65.1% nitrate DM basis 3 NCTRL = ad libitum bahiagrass hay g/kg of BW of molasses (basal diet); U = basal diet mg/kg of BW of urea; NIT = basal diet mg/kg of BW of NO 3- ; UB = U mg/kg of BW of BSS; NITB = NIT mg/kg of BW of BSS. 4 - Observed significance levels for: NPN = effect of NPN, NCTRL vs the mean of U + NIT + UB + NITB; NO 3 = effect of ecan (excludes NCTRL); B = effect of BSS (excludes NCTRL); B N = interaction of BSS and ecan. 5 NCTRL, U, NIT, UB, and NITB had 5, 5, 5, 5, and 4 experimental units, respectively; largest SEM was provided. 6 LM area and 12th rib fat thickness was measured on d 56 using d -28 as a covariate 7 Difference in LM area between d -28 and Difference in 12 th rib fat thickness between d -28 and Florida Beef Research Report

94 Table 4. Effect of BSS 1 and ecan 2 on liver mineral concentration. Treatment 3 P-value 4 Item NCTRL U NIT UB NITB SEM 5 NPN - NO 3 B B N Final liver mineral 6, mg/kg DM Cu Fe Zn Mn Se BSS = bismuth subsalicylate. 2 ecan = encapsulated calcium-ammonium nitrate (5Ca(NO 3) 2-NH 4NO 3) 65.1% nitrate DM basis 3 NCTRL = ad libitum bahiagrass hay g/kg of BW of molasses (basal diet); U = basal diet mg/kg of BW of urea; NIT = basal diet mg/kg of BW of NO 3- ; UB = U mg/kg of BW of BSS; NITB = NIT mg/kg of BW of BSS. 4 - Observed significance levels for: NPN = effect of NPN, NCTRL vs the mean of U + NIT + UB + NITB; NO 3 = effect of ecan (excludes NCTRL); B = effect of BSS (excludes NCTRL); B N = interaction of BSS and ecan. 5 NCTRL, U, NIT, UB, and NITB had 5, 5, 5, 5, and 4 experimental units, respectively; largest SEM was provided. 6 Liver mineral analyzed on d 56 using d -28 as a covariate Florida Beef Research Report

95 Supplementation of Cinnamaldehyde and Garlic Oil on Pre- and Postweaning Growth Performance of Beef Cattle Fed Warm-season Forages. P. Moriel 1, G. M. Silva 1, M. B. Piccolo 1, J. Ranches 1, J. M. B. Vendramini 1, and J. D. Arthington 1 Synopsis The cattle industry is searching for alternative feed additives that can modify ruminal microbial fermentation. Daily supplementation of such plant extracts did not impact growth performance of Brangus cow-calf pairs, but reduced fly counts of heifers grazing limpograss pastures. Summary We determined the effects of daily supplementation of extracts of cinnamaldehyde and garlic oil on preand post-weaning growth, internal parasite load, and horn fly infestation of grazing beef cow-calf pairs. Twenty-four Brangus cow-calf pairs were allocated into limpograss or bahiagrass pastures and provided daily supplement fortification with (CNG) or without (CON) cinnamaldehyde and garlic oil (300 mg/animal) for 61 days before weaning. After weaning, heifers remained on their respective pre-weaning treatments for 72 days. Effects of forage type and treatment were not detected for pre-weaning growth performance, fecal egg counts, and plasma concentrations of glucose and plasma urea nitrogen of heifers and cows. However, CNG heifers on limpograss pastures had less horn fly counts at weaning compared to CON heifers on limpograss pastures. Effects of treatment were not detected for post-weaning growth, total fecal egg counts, and plasma haptoglobin. Horn fly count did not differ between CNG and CON heifers on days 35 and 72. Thus, daily supplementation of CNG oil extracts did not impact growth, metabolic measurements, and fecal parasite load. However, daily CNG supplementation reduced horn fly counts of heifers grazing limpograss pastures, but not heifers grazing bahiagrass pastures. Introduction The cattle industry is searching for alternative feed additives since the use of antibiotics in animal feeds were banned by the European Union legislation in 2006 (European Union, 2003). Plant extracts, such as cinnamaldehyde and garlic oil, are generally recognized as safe for human and animal consumption, and can modify ruminal microbial fermentation and end products formation in vitro (Busquet et al., 2005) and in vivo (Cardozo et al., 2006). The addition of cinnamaldehyde decreased concentrations of acetate and ammonia, but increased concentrations of propionate, small peptides, and amino acids in the ruminal fluid of Holstein steers fed barley straw-based diets (Cardozo et al., 2006). Similarly, the addition of garlic oil (30 and 300 mg/l) decreased acetate concentration and increased propionate and butyrate concentrations in ruminal fluid (Busquet et al., 2005). Despite the capacity to modify ruminal fermentation, few studies focused on growth performance of beef cattle fed cinnamaldehyde and garlic oil. Hence, the objective of the current study was to evaluate the effects of daily supplementation of cinnamaldehyde and garlic oil on pre- and post-weaning growth, blood parameters associated with energy and protein metabolism, internal parasite load, and horn fly infestation of grazing beef cow-calf pairs. Materials and methods The experiment described herein was conducted at the Range Cattle Research and Education Center, Ona, Florida. At approximately 61 days before weaning, 24 cow-calf pairs were ranked by initial age and body weight, and randomly allocated into 1 of 4 limpograss or 4 bahiagrass pastures (3 cows-calf pairs/pasture). All cows received daily concentrate supplementation at a target consumption rate of 1 lb/cow (as-fed; 50:50 ground corn and cottonseed meal) in calf-exclusion feed bunks. All heifer calves received daily creep-feed supplementation at a rate of 2 lb/heifer (as-fed; 50:50 ground corn and cottonseed meal). Treatments were Florida Beef Research Report

96 randomly assigned to pastures (4 pastures/treatment), and consisted of: 1) Daily supplement fortification with cinnamaldehyde and garlic oil (CNG; 300 mg daily). 2) No supplement fortification (CON). Cows and heifer calves received their respective supplementation for 61 days until weaning. Immediately after weaning, heifers were transferred to 1 of 8 bahiagrass pastures and received daily supplementation of soybean hulls-based concentrate (1% of body weight; dry matter basis) added with (CNG) or without (CON) the same commercial extract of cinnamon and garlic oil (300 mg/heifer daily) for 72 days. The name of commercial product and the respective concentration of each ingredient was omitted purposely as requested by sponsor. Cow shrunk body weight and BCS were assessed on days -61 and 0, whereas heifer shrunk body weight were collected on days -61, 0, and 72, after 12 hours of feed and water withdrawal. Fecal samples were collected on days -61, 0, 49 and 72 to determine total fecal egg count. Blood samples (10 ml) were collected from jugular vein for plasma harvest on day -61 (cows and heifers), day -1 (cows and heifers), and 72 (heifers only) to determine the plasma concentrations of glucose and urea nitrogen (indicators of energy and protein metabolism). Additional blood samples (10 ml) were collected from jugular vein of all heifers on days 0, 1, 3 and 7 to determine plasma concentrations of haptoglobin (indicator of inflammatory and stress response). Total horn fly populations were recorded on individual cows and heifers using video recording while in their respective pasture on days -61, -32, -2, 35, and 71. Data were analyzed as a completely randomized design using the MIXED procedure of SAS with Satterthwaite approximation to determine the denominator degrees of freedom for the test of fixed effects. Pasture was considered the experimental unit. Heifer or cow (pasture forage type) and pasture (forage type treatment) were included as random effects in all analyses. Body weight, average daily gain, BCS, fecal egg count, and plasma measurements were analyzed as repeated measures and tested for fixed effects of treatment, pasture type, day, and resulting interaction. The proper covariance structure for all repeated measures analyses were selected based on the lowest Akaike information criterion. Results were reported as least-squares means, and separated using PDIFF, if a significant preliminary F-test was detected. Significance was set at P 0.05, and tendencies if P>0.05 and Results Effects of forage type, treatment, and any resulting interactions were not detected for growth performance and plasma glucose and urea nitrogen concentrations of heifers and cows (P 0.13; Table 1). A treatment day effect was not detected for cows (P 0.23). Daily CNG supplementation decreased overall fly count on heifers grazing limpograss pastures (P = 0.007), but not heifers grazing bahiagrass pastures (P = 0.66; forage type treatment effect; Table 2). No effects of forage type, treatment, and any resulting interactions were detected for total fecal egg count of heifers and cows (P 0.11). Although heifers supplemented with CNG tended (P = 0.08) to have less total fecal egg count than control heifers, this response was a reflection of CNG heifers starting the study with less total fecal egg count than control heifers (2.04 vs. 3.69±0.678 log 2 of eggs/g of fecal sample; P = 0.09). Effects of treatment and treatment day were not detected for post-weaning BW, ADG, shrink, and total fecal egg count (P 0.43; Table 3). However, a tendency for treatment day effect was detected for fly count (P = 0.10; Table 3). Fly count was greater for CNG vs. CON heifers on day 0 (P<0.006), but did not differ between CNG and CON heifers on days 35 and 72 (P 0.35). Effect of time, but not forage type, treatment, and any resulting interactions (P 0.23), was detected for plasma haptoglobin concentrations of heifers (P<0.0001; Figure 1) Florida Beef Research Report

97 In summary, daily CNG supplementation did not impact growth, plasma measurements of glucose and urea nitrogen, and fecal egg counts of heifers and cows during a 61-day pre-weaning phase. However, daily CNG supplementation (300 mg/head) decreased fly count of heifers, but not cows. Literature cited Busquet et al J. Dairy Sci. 88: Cardozo et al J. Anim. Sci. 84: European Union Off. J. Eur. Union 10/18/ 2003:L268/29 L268/43. Table 1. Pre-weaning growth performance and plasma concentrations of glucose and plasma urea nitrogen of heifers and cows. Treatment P-value Item CON CNG SEM Forage Trt Trt Forage Trt time Heifers Body weight, lb day day Average daily gain, lb/day Plasma glucose 1, mg/dl Plasma urea nitrogen 1, mg/dl Cows Body weight, lb day -61 1,026 1, day 0 1,035 1,053 Body weight change, lb BCS day day BCS change Plasma glucose 1, mg/dl Plasma urea nitrogen 1, mg/dl Mean concentration of plasma glucose and urea nitrogen obtained on days -54 and Florida Beef Research Report

98 Table 2. Overall pre-weaning fly count of heifers. Forage P-value Treatment Bahiagrass Limpograss P-value 1 SEM Forage Trt CNG CON P-value P-value for comparison of forage type within treatment. 2 P-value for comparison of treatment within forage type. Table 3. Post-weaning growth performance, fly count, and fecal egg count (FEC) of heifers. Treatment P-value Item CON CNG SEM Trt Trt Day Heifer body weight, lb day day Average daily gain, lb/day Fly count/head day 0 252y 101x day x 133x day 72 21x 12x Mean Total FEC1, log2 of eggs/g fecal sample day day day Mean x-y Within a row, means without a common superscript differ (P 0.05). 1 FEC = Fecal egg count Florida Beef Research Report

99 Plasma haptoglobin, mg/ml x z yz y yz Day relative to weaning Figure 1. Post-weaning plasma concentrations of haptoglobin (mg/ml) of heifers. xyz Means without a common superscript differ (P 0.05) Florida Beef Research Report

100 Florida Beef Research Report

101 Effect of Post-weaning Trace Mineral Source on Measures of Growth, Performance, and Sexual Development in Pre-pubertal Bos taurus Beef Bulls D. Price 1, M. Hersom 1, J. Yelich 1, M. Irsik 2, O. Rae 2 Synopsis The results of the current study demonstrate that supplementation of prepubertal Bos taurus bulls postweaning with inorganic or organic trace mineral source enabled bulls to maintain adequate trace mineral concentrations over the period of pubertal development. Supplementation of bulls with organic trace mineral resulted in increased IGF-1 concentrations and hastened the attainment of sexual maturity in a limited population of bulls. Summary The objective was to investigate the effect of post-weaning trace mineral (TM) supplement source on Bos taurus beef bull (Angus, n = 9; Aubrac, n = 5) growth, performance, TM status, and sexual development over a 224 d period. Bulls (231 ± 4 d, 573 ± 11 lb, n = 14, 7 per TM) were blocked by sire, age, and weaning BW and randomly assigned to 1 of 2 TM supplement sources 1) inorganic (ING), Na selenite, Co, Cu, Mn, and Zn as salt sulfates, or 2) organic (ORG), Se-yeast and Co, Cu, Mn, and Zn as proteinates. Bull diet included cracked corn, cottonseed hulls, a protein pellet, and the TM supplement (1.0 lb lb BW -1 d -1 in a pellet). Weekly blood samples were collected for serum IGF-1 concentration determination. Weekly body weight (BW) and bi-weekly semen collection (motility and morphology initiated when scrotal circumference (SC) 26 cm), SC, and BCS (scale 1-9) were recorded. Serum and liver biopsies were collected every 56 d to determine TM status. Hip height (HH) and ultrasound measurements of LM area (LMA), 12th rib back fat thickness (FAT), and LM intramuscular fat percentage (IMF) were recorded every 28 d. At puberty, no differences (P>0.10) based on TM source occurred for any performance or semen parameters measured. The ORG (399 ± 9 d, 42.5 ± 2.7 %) bulls tended (P = 0.10) to reach sexual maturity 25 d earlier and had greater sperm motility than ING (424 ± 9 d, 35.0 ± 2.7 %) bulls, respectively. At sexual maturity, no other performance or semen parameters differed (P>0.10) by TM source. Bull performance, liver TM, and IGF-1 concentrations increased (P<0.01) from trial start. No overall effect (P>0.10) of TM source occurred for mean performance or liver TM concentrations, but IGF-1 concentrations were affected (P<0.01) by a TM source day interaction, with greater IGF-1 in ORG compared to ING bulls at several time points. Bull pubertal traits and trial performance were not affected by TM source. However, ORG TM source may increase IGF-1 concentrations and shorten the time it takes bulls to reach sexual maturity. Introduction Trace minerals have integral roles in biochemical, physiological, and metabolic systems as they are incorporated into numerous enzymes or may act as cofactors in enzymatic reactions. Both Zn and Se are known to have roles in spermatogenesis, so deficiencies of these TM can interfere with proper spermatozoal production, development, and maturation (Bedwal and Bahuguna, 1994), which ultimately affect bull fertility. Previous research on TM and beef bulls has typically been carried out in yearling or sexually mature bulls. In sexually mature beef bulls supplemented with organic complexed forms of Co, Cu, Mn and Zn, greater sperm motility (Rowe et al., 2014) was reported. While a greater percentage of normal sperm (Arthington et al., 2002) was observed in yearling beef bulls supplemented with Zn proteinate compared to inorganic sulfate forms. Recently, Geary et al. (2016), reported peripubertal bulls supplemented with complexed Co, Cu, Mn, and Zn reached puberty 15 d earlier than those that were supplemented with sulfate forms. However, research involving the potential effects of TM on beef bull sexual development is minimal and needs further investigation. Therefore, the aim of this experiment was to determine the effect of post-weaning TM supplement source on bull growth, performance, body composition, and sexual development Florida Beef Research Report

102 Methods and Materials All bulls used in the experiment were derived from cattle in the research herd at the University of Florida s Boston Farm at the Santa Fe River Ranch experiment station in Alachua, Florida. Bulls were weaned and transported to experimental facilities located at the University of Florida s Beef Teaching Unit in Gainesville, Florida 2 wk prior to trial initiation. The effect of post-weaning TM supplement source (inorganic, ING or organic, ORG) on bull TM status, growth, performance, and pubertal development was investigated in pre-pubertal Bos taurus beef bulls (n = 14, 7/TM source; Aubrac, n = 5; Angus, n = 9). Bulls were balanced by breed, age, weaning BW, and sire and randomly allotted to receive one of two TM (Co, Cu, Mn, Se, and Zn) supplement sources, 1) inorganic, ING; Na selenite and Co, Cu, Mn and Zn as salt sulfates or 2) organic, ORG; Se-yeast (Selplex, Alltech Inc., Nicholasville, KY) and Co, Cu, Mn and Zn as proteinates, (Bioplex, Alltech Inc., Nicholasville, KY). Both TM supplements were formulated to meet NRC requirements (NRC, 2000) and were manufactured as a pellet in a single batch by the Lakeland Nutrition Group (Lakeland, FL). The formulation of the ORG TM source was based upon the manufacturer s proprietary bioavailability of minerals. Bulls were maintained in two 2.0 ac pastures (1 pasture per TM source) at the University of Florida Beef Teaching Unit in Gainesville, FL for the entire 224 d of the experiment, which began September 25, 2013 and ended May 5, Bulls were pen fed daily and had access to Bermudagrass hay (Cynodon dactylon) and water ad libitum. Bull diets consisted of a TMR that included cottonseed hulls, cracked corn, protein pellet, fat, and the TM supplement which was delivered in a wheat-middling pellet and fed at a rate of 1.0 lb 1000 lb BW -1 d -1. Final analysis of TM supplements, TMR, forage, and pasture were carried out at a commercial laboratory (Dairy One, Ithaca, NY) and are presented as overall means (Table 1). Bulls had BW recorded weekly, BCS recorded every 2 wk, and HH recorded at 28-d intervals for determination of performance. Bull SC was measured with scrotal tape and recorded every 2 wk. Once a bull reached a SC of 26 cm, BSE were conducted at 2 wk intervals by a trained veterinarian which included measurements of BCS, SC, and semen collection by electroejaculation. Semen samples were used to quantify sperm motility and morphology, and concentration of sperm as determined by hemoctyometer. Bull serum and liver biopsy samples were collected at 56-d intervals from the initiation of the trial for determination of TM status. Total sperm/ml were calculated by: average number of sperm (dilution factor) ( ). Puberty was defined as an ejaculate that contained sperm and 10 % motility. Sexual maturity was defined as having passed 2 consecutive BSE. Receiving a satisfactory potential breeder designation at BSE is defined by the Society for Theriogeneology, which required a bull to a have a SC that reached a threshold for the age of the bull, an ejaculate that had sperm, 30 % motility, and 70 % normal morphology. Weekly serum samples were collected for determination of IGF-1 concentrations by RIA. To determine bull TM status, blood and liver biopsy (n = 14, 7/TM source) samples were collected for TM analysis at 56 d intervals and were initiated at trial start (d 0). All mineral analysis for liver and serum (Co, Cu, Fe, Mn, Mo, Se, and Zn) was carried out by an Agilent 7500ce Inductively Coupled Plasma Mass Spectrometer (ICP-MS, Agilent Technologies Inc., Santa Clara, CA) at a commercial laboratory (DCPAH, Michigan State University, Lansing, Michigan). Data are presented on a DM basis. All statistical analysis was a carried out in SAS 9.4 (Cary, NC) and used bull as the experimental unit. The PROC MIXED procedure was utilized for data at the estimated date of puberty and sexual maturity with the fixed effect of TM source. A repeated measures PROC MIXED analysis was used to analyze performance, IGF-1 concentrations, and blood and liver TM concentrations with the fixed effects of TM source, day of trial, and their interaction. The random statement included bull nested within TM source. A repeated measures PROC MIXED analysis was used to analyze IGF-1, SC, sperm concentration, motility and morphology data with the fixed effects of TM source, day relative to puberty or sexual maturity, and their interactions; where the day a bull reached puberty or sexual maturity was considered as d 0 for that particular bull. Survival analysis were used to calculate the time to puberty and time to maturity with the Florida Beef Research Report

103 Kaplan-Meyer test by PROC LIFETEST. Cox s proportional hazards for puberty and maturity were calculated using the PROC PHREG function. Pearson correlations between IGF-1 and performance and body composition data, between seminal traits and liver TM concentrations, and between serum and liver TM concentrations were analyzed with PROC CORR. Data are presented as LSMEANS ± SE. Differences between and within treatment means were identified by using PDIFF. Statistical significance was declared at P 0.05 and a tendency was 0.05 <P Results At puberty, there were no TM source differences (P 0.39) in any performance or semen parameters measured (Table 2). There was no (P = 0.94) difference in the time to reach puberty between the TM sources and the average age at puberty was 345 and 343 ± 13 d for ING and ORG bulls, respectively. Evaluation of SC and semen parameters adjusted for the day of puberty (Figure 1), showed no (P>0.05) differences based on TM source or TM source day, with the exception of percentage of normal sperm which were affected by TM source day (P = 0.04). The ING bulls had greater (P<0.05) percentages of normal sperm on d 14 and 42 relative to puberty compared to ORG bulls. Additionally, all semen parameters with the exception of primary abnormalities were affected (P<0.001) by day relative to puberty. Across bulls, SC, sperm concentration, gross and individual motility, and the percentage of normal sperm increased, the percentage of secondary abnormalities decreased, while percentage of primary abnormalities exhibited little variation. Not all bulls reached sexual maturity by the end of the experiment, so data analysis at sexual maturity only included the 8 bulls (4/TM source) that reached sexual maturity during the trial and should be interpreted with caution. At sexual maturity, there were no (P 0.10) effects of TM source on BW, BCS, SC, or any semen morphology parameters measured (Table 2). While there were no differences (P = 1.00) in gross motility by TM source, the ORG bulls tended (P = 0.10) to have a greater percentage of individual motility compared to the ING bulls at sexual maturity. No other TM source effects were evident at sexual maturity. Though not statistically significant (P = 0.70), the ORG bulls reached sexual maturity 25 d earlier than ING bulls. Adjusting for day relative to sexual maturity, there was no (P>0.05) TM day effect for any seminal traits, nor was there an effect (P 0.14) of TM source on SC, BCS, sperm counts, morphology, or individual motility. Across days, SC, sperm concentration, gross and individual motility and percentage of normal sperm increased (P 0.01), while the percentages of primary abnormalities tended (P = 0.06) to decrease and secondary abnormalities decreased (P<0.001). Concentrations of IGF-1 increased (P<0.01) by day from trial initiation in all bulls, and were not affected (P = 0.14) by TM source. However, TM source day affected (Figure 2, P = 0.01) serum IGF-1, as bull IGF-1 did not differ by TM source on d 0, but ORG bulls had greater IGF-1 concentrations on d 42, 56, 63, 70, 203, and 210 of the trial compared to ING bulls. When IGF-1 concentrations were adjusted to the day relative to puberty and the day relative to sexual maturity, there tended (P = 0.10) to be greater mean IGF-1 concentrations in ORG (215.8 ± 25.8 and ± 33.0 mg/dl) bulls compared to ING (151.1 ±25.5 and ± 33.0 mg/dl) bulls, adjusted for puberty and maturity, respectively. All bull serum TM concentrations varied (P 0.04) by day of the trial (Table 3). Bull serum concentrations of Co (4.42 ± 0.45 ng/ml) and Mn (2.08 ± 0.09 ng/ml) were greater (P 0.04) in ING compared to ORG (2.84 ± 0.45 and 1.78 ± 0.09 ng/ml, for Co and Mn, respectively) bulls when pooled across days. Additionally, ING (0.72 ± 0.03 µg/ml and 5.86 ± 0.43 ng/ml, respectively) bulls tended (P 0.10) to have greater serum Cu and Mo compared to ORG (0.72 ± 0.03 µg/ml and 4.77 ± 0.43 ng/ml, respectively) bulls when concentrations were pooled across days. No effect (P>0.05) of TM source was observed for serum Fe, Se, or Zn. With the exception of Co (P = 0.01), no serum TM concentrations were affected (P>0.05) by TM source day. While serum Co did not differ between ORG and ING on from d 0 through d 112, by d 168, ING had greater Co than ORG bulls. All liver TM concentrations did not differ (P 0.11) by TM source, but all liver TM differed (P 0.01) by day (Table 4). There was a TM source day effect (P 0.04) for liver Co, Cu, Mn, Mo, and Se and tended (P = 0.07) to be a TM source day affect for liver Zn. Liver Fe was the only TM not affected Florida Beef Research Report

104 (P = 0.28) by TM source day. While ING and ORG bulls had similar (P 0.05) Co and Cu liver concentrations at d 0, by d 168 (Cu) and d 224 (Co), ING had greater (P 0.05) Co and Cu compared to ORG bulls. Liver Mn concentrations were greater (P 0.05) in ORG on d 112, and were greater (P 0.05) in ING on d 168 ING. However, concentrations decreased by d 224, when TM sources did not differ (P 0.05). Concentrations of Mo tended (P<0.10) to differ between ING and ORG on d 0 and 56, but did not differ (P>0.05) at any additional sample points. While ING and ORG bulls had similar (P>0.05) Se concentrations on d 0, ORG had greater (P<0.10) Se on d 56 and 112, but lesser (P<0.10) Se on d 168 and 224 compared to ING bulls. Liver Zn was greater (P<0.05) on d 0 in ORG bulls, but did not differ (P>0.05) between treatments at any other time point. Associations between serum and liver TM values were observed for Co (P<0.001, r = 0.69), Cu (P = 0.03, r = -0.26), Mo (P = 0.06, r = 0.23), and Zn (P = 0.08, r = 0.21), while there were no correlations (P>0.05) between serum and liver Fe, Mn, and Se. Literature Cited Arthington, et al Prof. Anim. Sci. 18: Bedwal, R. S., and A. Bahuguna Experientia. 50: Geary, et al Anim. Reprod. Sci. 168:1 9. Rowe, et al Prof. Anim. Sci. 30: Florida Beef Research Report

105 Table 1. Trace mineral supplement, feed, and forage component analysis (DM basis) for post-weaning bulls 1 Trace Mineral Supplement 2 Forage Component Inorganic Organic TMR Pasture Hay DM, % CP, % TDN, % Ca, % P, % Mg, % K, % Na, % S, % Ash, % Co, PPM Cu, PPM I, PPM Fe, PPM Mn, PPM Mo, PPM Se, PPM Zn, PPM Vitamin A 3, IU/kg 31,614 31, Vitamin D 33, IU/kg 2,836 2, Vitamin E 3, IU/kg Analysis of feedstuffs was carried out at Dairy One, (Ithaca, NY). 2 Trace mineral supplements were formulated and manufactured as a single batch by Lakeland Nutrition Group (Lakeland, FL) and provided to bulls in a pellet at a rate of 1.0 lb lb BW -1 d Formulation values Florida Beef Research Report

106 Table 2. Effect of inorganic (ING) or organic (ORG) trace mineral source supplemented post-weaning on bull characteristics at puberty and sexual maturity Puberty 1,3 Sexual maturity 2,4 Item ING ORG SEM ING ORG SEM Bulls, n Age, d BW, lb ,054 1, ADG 5, lb/d BCS Hip height, cm Scrotal circumference, cm Sperm concentration, 10 6 cells/ml Gross motility, % Individual motility, % Normal sperm, % Primary abnormalities, % Secondary abnormalities, % Puberty determined when ejaculate had at least sperm cell/ml and at least 10% individual motility. 2 Sexual maturity declared when bulls passed 2 consecutive BSE. 3 Trace mineral source did not affect (P>0.10) any parameter at puberty. 4 Trace mineral source did not affect (P>0.10) any parameter except individual motility (P = 0.10) at sexual maturity. 5 ADG, calculated from d 0 of trial through day bull reach puberty or maturity Florida Beef Research Report

107 SC, cm SC Concentration Sperm, 10 6 cells/ml A Day relative to puberty 0 Individual motility, % Individual motility Gross motility Gross motility B Day relative to puberty 0 Sperm morphology, % C ING Normal Primary ORG Normal Secondary Day relative to puberty Figure 1. Bull seminal parameters by day relative to puberty. Mean ± S.E. bull A) scrotal circumference (SC) and sperm concentrations; B) percentage of individual and gross motility, and C) sperm morphology percentages (normal sperm, primary and secondary abnormalities) in bulls supplemented with inorganic (ING) or organic (ORG) trace mineral (TM) sources post-weaning by day relative to puberty. Day relative to puberty affected (P<0.001) all seminal parameters except for primary abnormalities (P>0.10). No TM source day effect (P>0.10) for all seminal parameters, except normal sperm (P = 0.04), as ING greater (P<0.05) on d 14 and 42 compared to ORG bulls. TM source, (P>0.10) Florida Beef Research Report

108 ING ORG * * IGF-1, ng/ml * * * * * Day of trial, d Figure 2. The effect of inorganic (ING) or organic (ORG) trace mineral (TM) supplement sources on post-weaning bull serum IGF-1 concentrations. TM source day, (P<0.01). * Means with different superscripts differed within day, (P<0.05) Florida Beef Research Report

109 Table 3. Effect of inorganic (ING) or organic (ORG) post-weaning trace mineral (TM) supplement source on bull serum TM concentrations Day (D) of trial P-value Item SEM TM D TM D Co, ng/ml < ING 1.77 w 5.54 xz 3.23 wy 4.71 xy 6.87 az ORG 1.21 x 5.18 y 2.60 x 2.91 x 2.30 bx Cu, µg/ml < ING ORG Fe, µg/dl ING ORG Mn, ng/ml ING ORG Mo, ng/ml < ING ORG Se, ng/ml < ING ORG Zn, µg/ml ING ORG a-b Column means with different superscripts differed within day (P<0.05). w-z Row means with different superscripts differed by day (P<0.05) Florida Beef Research Report

110 Table 4. Effect of inorganic (ING) or organic (ORG) post-weaning trace mineral (TM) supplement source on bull liver (µg/g) TM concentrations (on a DM basis) Day (D) of trial P-value Item SEM TM D TM D Co ING 0.29 v 0.46 wx 0.38 vw 0.53 x 0.49 wx < ORG 0.28 v 0.55 x 0.40 w 0.43 w 0.34 vw Cu ING 146 v 163 v 254 w 280 bw 331 bx < < ORG a 189 a Fe ING ORG Mn ING 5.86 v 4.91 v aw bx 9.93 w < ORG 6.41 v 6.61 v bx aw 8.07 vw Mo ING 2.71 w 2.34 v 2.64 vw 2.73 w 2.94 w < < 0.01 ORG 2.29 v 2.71 wx 2.51 vw 3.01 xy 3.19 y Se ING 0.77 v 1.13 aw 1.49 x 2.37 by 2.10 z < < ORG 0.80 v 1.60 bw 1.84 w 1.86 aw 1.73 w Zn ING < ORG a-b Column means with different superscripts within day differ (P<0.05). v-z Row means with different superscripts differed by day (P 0.05) Florida Beef Research Report

111 Evaluation of Brassica carinata as a Protein Supplement for Growing Beef Heifers T. M. Schulmeister 1, M. Ruiz-Moreno 1, G. Medeiros 1, M. Garcia-Ascolani 1, F. M. Ciriaco 1, D. D. Henry 1, G. C. Lamb 2, J. C. B. Dubeux 1 and N. DiLorenzo 1 Synopsis Brassica carinata is a new non-food oilseed crop in Florida with the potential of producing high-quality biofuel. The high-protein meal obtained as a byproduct of oil extraction increased daily weight gains by 0.62 lb/d when used as a protein supplement, fed at 0.3% of body weight daily to heifers fed bermudagrass hay ad libitum over two consecutive years. Summary An experiment was conducted over two consecutive years, to determine the effects of the B. carinata meal on performance, time to attainment of puberty and blood profile of growing beef heifers consuming bermudagrass hay. Sixty-four Angus crossbred heifers (529 ± 86 lb of initial bodyweight, BW) were randomly allocated to 18 pens, blocked by initial BW. All heifers had ad libitum access to water and bermudagrass hay (Cynodon dactylon). Pelleted B. carinata meal was provided daily to treatment pens. Body weight and blood samples were collected weekly for 70 d, before daily supplementation. Plasma was analyzed for concentrations of progesterone, triiodothyronine, thyroxine, ceruloplasmin, and haptoglobin. Supplementing B. carinata meal improved average daily gain (ADG; P<0.001) in heifers consuming bermudagrass hay. Time to attainment of puberty in heifers, as evidenced by concentrations of progesterone, was not affected (P = 0.68) by the inclusion of B. carinata meal. Thyroid hormone and acute phase protein production and synthesis were not affected (P = 0.28) by the inclusion of B. carinata meal. Introduction Brassica carinata is a non-food oilseed crop with a favorable very long chain fatty acid composition for conversion to biofuel (Marillia et al., 2013). Oil extracted from the seed has been utilized as a 100% dropin jet biofuel, promoting the use of B. carinata as a renewable and potentially sustainable resource (AAFC, 2015). B. carinata has been grown commercially for several years in Canada as a summer crop, however, cultivation is currently underway in Florida as the climate is excellent due to the many intrinsic characteristics of B. carinata, ranging from drought tolerance and resistance to extreme changes in temperature, as well as the ability to be planted on fallow lands during the winter to prevent erosion and depletion of essential nutrients from the soil (Bliss et al., 2014). A high-protein meal (~40% CP) is obtained as a byproduct of oil extraction; however, this meal has not been extensively tested as a potential protein supplement for cattle. Analysis of the meal yields low concentrations of sinigrin and progoitrin, byproducts of ruminal degradation of glucosinolates (EFSA, 2008), which have been implicated in decreased intake, interference of thyroid hormone metabolism, and impaired fertility and reproductive performance in cattle. Beef heifer development is a highly profitable market in Florida, in which there is typically a 30% replacement of heifers annually, and although there is an abundant production of forage in the Southeast, feed is the largest cost in a cattle operation. With the most common forages in this region being of limited nutritive value and often not sufficient to support high levels of production, there are some critical periods during the year in which there is a need for supplementation with protein in cattle operations in the Southeast (Hersom et al., 2011). Combined with the abundance of forages, another advantage of beef production in the Southeastern U.S. is the availability of several byproducts from diverse industries, which can have great nutritional value for cattle and can therefore provide an opportunity to correct nutritional imbalances through supplementation. Feeding growing heifers in the winter is a substantial cost to the producer, however appropriate nutrition is vital to both the heifer s health and reproductive status as nutritional requirements are greater at this stage (Kunkle et al., 2001) Florida Beef Research Report

112 Considering the poor quality of winter forages available in Florida, B. carinata meal could be a viable source of protein supplementation to meet the nutritional requirements of growing heifers and provide economic benefit to the producer as well. The objective of this study was to evaluate the effects of supplementation with B. carinata meal on performance and attainment of puberty in growing Angus crossbred heifers consuming bermudagrass hay. Materials and Methods The experiment was conducted at the NFREC in Marianna, FL. Pelleted B. carinata meal was provided by Agrisoma Biosciences, Inc. (Gatineau, Quebec). Sixty-four Angus crossbred heifers were used in a generalized randomized block design. On d -1 and 0, heifers were weighed to obtain a two-day average weight, stratified and blocked by initial BW (2 blocks: lightest and heaviest) and randomly assigned to either BCM (0.3% of live BW of B. carinata meal pellets, as fed) or CTL (0.0% supplementation of live BW, bermudagrass hay only). Heifers were provided ad libitum access to bermudagrass hay (Cynodon dactylon) and water, with BCM provided daily, at 0800, to heifers in feed bunks. Refusals were weighed and recorded for the first 4 d, however by d 5 all heifers were consuming the entire amount of meal supplemented. Blood samples were collected on d 0, before feeding, for analysis of initial concentrations of thyroid hormones, progesterone, and acute phase proteins in plasma. Heifers were weighed and bled every 7 d for the 70 d period. Blood was collected, centrifuged, and plasma was stored at -20 C for further analyses. On d 69 and 70 heifers were weighed again for a two-day average weight. Plasma samples were analyzed for concentrations of progesterone using the DPC Immulite 1000 chemiluminescent immunoassay system and results were analyzed with SAS using the LIFETEST procedure to determine the effect of treatment on time of attainment of puberty. Data were analyzed as a generalized randomized block design using the MIXED Procedure of SAS (SAS Institute Inc., Cary, NC). Pen was considered the experimental unit and the model included the fixed effects of treatment, and the random effect of block. Significance was determined at P 0.05 and tendencies were considered when 0.05<P Results Chemical composition of B. carinata meal and bermudagrass hay fed to heifers is presented in Table 1. Time to attainment of puberty was not affected (P = 0.68) in heifers receiving BCM, compared with the CTL, as presented in Figure 1. ADG was significantly greater (P<0.001) for the BCM, compared with the CTL, as presented in Figure 2. Concentrations of thyroid hormones and haptoglobin in heifers were not affected (P = 0.28) by supplementation of BCM, however concentrations of ceruloplasmin were decreased (P<0.001) in heifers receiving BCM compared with the CTL, as presented in Table 2. Results indicate that feeding B. carinata meal as a protein supplement at 0.3% of BW/d is a viable option for increasing ADG of growing beef heifers. Literature Cited AAFC Carinata: an oilseed ready for lift-off. (Accessed 18 July 2017.) Bliss, C. M. et al Carinata Production in Florida. University of Florida, IFAS, Florida Coop. Ext. Serv., Animal Science Dept., Electronic Data Information Source (EDIS) Publication SS-AGR Cole, N. A. et al Prof. Anim. Sci. 27: EFSA. European Food Safety Authority EFSA Journal. 6:590. Hersom, M. et al Proceedings of the 22 nd Florida Ruminant Nutrition Symposium, p Kunkle, W. E. et al J. Anim. Sci. 77:1-11. Kunkle, W. E. et al Florida Cow-Calf Management, 2nd Edition - Feeding the Cow Herd Florida Beef Research Report

113 University of Florida, IFAS, Florida Coop. Ext. Serv., Animal Science Dept., Electronic Data Information Source (EDIS) Publication AN Krizsan, S. J. and P. Huhtanen J. Dairy Sci. 96: Marillia, E.-F. et al Biocatal Agric Biotechnol. 3: Acknowledgements The authors would like to thank the staff and interns at the NFREC Marianna, for all the assistance with this project. Table 1. Chemical composition of Brassica carinata meal and bermudagrass hay fed to beef heifers 1. Treatment 2 Item BCM Bermudagrass hay DM, % 89.1 ± ± 1.84 Glucosinolates 3, µmol/g CP, % 43.6 ± ± 2.12 NFC 4, % 21.7 ± ± 6.58 NDF, % 23.6 ± ± 8.13 ADF, % 13.2 ± ± 8.91 EE 5, % 2.5 ± S, % 1.7 ± TDN, % 76 ± ± Analyzed by a commercial laboratory using a wet chemistry package (Dairy One, Ithaca, NY) 2 BCM: B. carinata meal pellets; Bermudagrass hay (Cynodon dactylon) fed ad libitum; values averaged over 2 years. 3 Analyzed by Agrisoma Biosciences, Inc., Gatlineau, Quebec. 4 NFC = non-fiber carbohydrates. 5 EE = ether extract. Table 2. Effects of Brassica carinata meal supplementation on thyroid hormone 1 metabolism and acute phase protein response in Angus crossbred heifers fed bermudagrass hay ad libitum. Treatment 2 P-value 3 Item 4 BCM CTL SEM 5 TRT T 3, ng/dl T 4, µg/dl Haptoglobin, mg/ml Ceruloplasmin, mg/dl 9.78 b a < a,b Within a row, means with different superscripts differ, P< Thyroid hormones: T 3 = triiodothyronine; T 4 = thyroxine. 2 BCM: Brassica carinata meal pellets; CTL: bermudagrass hay (Cynodon dactylon) fed ad libitum; values averaged over 2 years. 3 Observed significance levels for treatment. 4 Concentrations of metabolites in plasma. 5 Pooled standard error of treatment means, n = 18 pens Florida Beef Research Report

114 Puberty, d BCM Treatment CTL Figure 1. Time to attainment of puberty in heifers supplemented with B. carinata meal. ADG (lbs/d) ADG over 2 consecutive years BCM Treatment CTL Figure 2. Effect of supplementing BCM on performance of beef heifers fed bermudagrass hay ad libitum Florida Beef Research Report

115 Effects of Gradual Reduction in Frequency of Energy Supplementation on Growth and Immunity of Beef Steers G. M. Silva 1, J. Ranches 1, and P. Moriel 1 Synopsis Gradually reducing the frequency of energy supplementation did not negatively impact growth, but alleviated indices of inflammation and prevented detrimental effects on vaccine response against BVDV- 1a and PI-3 viruses compared to steers offered concentrate 3 times weekly during the entire study. Summary We evaluated the effects of a gradual reduction in the frequency of supplementation on growth and measurements of immunity of beef steers. Fourteen days after weaning, Angus steers (n = 42, 440 ± 11 lb; 175 ± 4 days of age) were stratified by body weight and age, and then randomly assigned to 1 of 3 treatments that consisted of similar weekly concentrate dry matter supplementation (1% of body weight multiplied by 7 days) that was divided and offered daily from days 0 to 42 (7X), 3 times weekly from days 0 to 42 (3X; Monday, Wednesday, and Friday), or daily from days 0 to 15 and then 3 times weekly from days 16 to 42 (7-3X; Monday, Wednesday, and Friday). Steers were vaccinated against infectious bovine rhinotracheitis (IBR), bovine viral diarrhea virus (BVDV), and parainfluenza-3 (PI-3) on days 0 and 15. Average body weight, average daily gain, feed efficiency, hay dry matter intake, and total dry matter over the 42-day period did not differ among treatments. Plasma concentrations of cortisol and mean serum BVDV-1a titers also did not differ among treatments, but overall plasma haptoglobin concentrations were greater for 3X steers compared to 7-3X and 7X steers. Also, 3X steers had less mean serum titers against IBR and less seroconversion to PI-3 virus on day 15 compared to 7-3X and 7X steers. In summary, gradually reducing the frequency of energy supplementation during a 42-day preconditioning period did not negatively impact growth, but alleviated inflammation and prevented negative effects on calf vaccine response. Introduction Beef calves that are preconditioned typically experience multiple management processes (for example, weaning, vaccination, and feedlot entry) that cause an acute phase protein response (APR) and impair growth performance (Arthington et al., 2008, 2013). Recently weaned beef calves require energy supplementation to improve body weight gain and economic return during preconditioning, but daily concentrate supplementation increases production costs associated with labor, fuel, and equipment (Cooke et al., 2008). Decreasing the frequency of energy supplementation from daily to 3 times weekly reduced feeding costs without changing the weekly supplement amount (Drewnoski et al., 2014). However, this strategy leads to fluctuations in forage and nutrient intake, which further exacerbates the post-vaccination inflammatory response and decreases growth and vaccine-induced production of antibodies against bovine viral diarrhea virus (Artioli et al., 2015; Moriel et al., 2016) suggesting that decreasing the frequency of energy supplementation during preconditioning and vaccination should not be used. Therefore, we hypothesized that by adding a gradual reduction of frequency of supplementation by offering the concentrate daily for 14 days until first vaccination, and then 3 times weekly until the end of preconditioning period, would allow producers to reduce feeding costs without impairing vaccine response and growth of preconditioning beef calves. Materials and Methods Florida Beef Research Report

116 The present study was conducted from May to July 2016 at the Mountain Research Station, Waynesville, NC. Forty-Two Angus steers were used in the study in a completely randomized design. On day 0, steers were stratified by body weight and age, and randomly assigned into 1 of 14 drylot pens (3 steers/pen). From days 0 to 42, steers were provided free choice access to ground tall fescue hay and supplemented with a 50:50 soybean hulls pellets and corn gluten pellets concentrate (dry matter basis). Treatments were randomly assigned to pens and consisted of similar weekly concentrate dry matter supplementation (1% of body weight multiplied by 7 days) that was divided and offered daily from days 0 to 42 (7X; 4 pens), 3 times weekly from days 0 to 42 (3X; Monday, Wednesday, and Friday; 5 pens), or daily from days 0 to 15 and then 3 times weekly from days 16 to 42 (7-3X; 5 pens). Individual body weight was measured before feeding on days 0 and 42, following 12 hours of feed and water withdrawal. On days 0 and 15, all steers were vaccinated against IBR, BVDV-1a, and PI-3 viruses. Blood samples were collected to evaluate serum antibody titers against IBR, BVDV-1a, and PI-3 viruses and plasma concentrations of haptoglobin and cortisol. All data were analyzed as a completely randomized design using the MIXED procedure of SAS (SAS Institute Inc., Cary, NC, USA, version 9.4). Pen was considered the experimental unit. Growth performance was tested for fixed effects of frequency of supplementation, using steer (pen) and pen (treatment) as random effects. Plasma and serum measurements were tested for fixed effects of treatment, day, and resulting interaction using steer (pen) as subject and pen (treatment) as random effect. Significance was determined at P 0.05 and tendencies were considered when 0.05<P Results Overall body weight, average daily gain, feed efficiency, hay dry matter intake, and total dry matter intake over the 42-day period did not differ among treatments (P 0.26; Table 1). Plasma concentrations of cortisol and mean serum BVDV-1a titers also did not differ among treatments (P 0.35; Table 2), but overall plasma haptoglobin concentrations were greater for 3X steers compared to 7-3X and 7X steers (P 0.05; Table 2). Also, 3X steers had less mean serum IBR titers (P 0.05) and less percentage of calves responding to vaccination against PI-3 virus on day 15 compared to 7-3X and 7X steers (P 0.05; Table 2). In summary, a gradual reduction on frequency of energy supplementation during a 42-day preconditioning period did not negatively impact growth, but alleviated indices of inflammation and prevented detrimental effects on vaccine response against BVDV-1a and PI-3 viruses compared to steers offered concentrate 3 times weekly during the entire study. Literature cited Artioli, L. F. A., et al J. Anim. Sci. 93: Arthington, J. D., et al J. Anim. Sci. 86: Arthington, J. D., et al J. Anim. Sci. 91: Cooke, R. F., et al J. Anim. Sci. 86: Drewnoski, M. E., et al J. Anim. Sci. 92: Moriel, P., et al J. Anim. Sci. 94: Florida Beef Research Report

117 Table 1. Growth performance of beef steers provided similar weekly concentrate dry matter supplementation that was divided and offered daily from days 0 to 42 (7X; 4 pens), 3 times weekly from days 0 to 42 (3X; Monday, Wednesday, and Friday; 5 pens), or daily from days 0 to 15 and then 3 times weekly from days 16 to 42 (7-3X; 5 pens). 1 Treatment P-value Item 3X 7-3X 7X SEM Frequency Body weight 2, lb day day Average daily gain, lb/day days 0 to days 15 to days 0 to Total hay dry matter intake, lb days 0 to days 16 to days 0 to Total dry matter intake, lb days 0 to days 16 to days 0 to Gain:Feed From days 0 to 42, steers were provided daily free-choice access to ground tall fescue hay. Weekly concentrate dry matter intake = 1% of body weight multiplied by 7 days. 2 Least square means covariate-adjusted to body weight on day 0 (P<0.0001). Individual body weight was measured on days 0 and 42, following 12 hours of feed and water withdrawal. 3 Calculated by dividing total body weight gain by total dry matter intake from days 0 to 42. Table 2. Plasma and serum measurements of beef steers provided similar weekly concentrate dry matter supplementation that was divided and offered daily from days 0 to 42 (7X; 4 pens), 3 times weekly from days 0 to 42 (3X; Monday, Wednesday, and Friday; 5 pens), or daily from days 0 to 15 and then 3 times weekly from days 16 to 42 (7-3X; 5 pens). 1 Treatment P-value Item 3X 7-3X 7X SEM Freq. Day Freq. Day Plasma haptoglobin, mg/dl 0.44a 0.37b 0.37b < Plasma cortisol 2, ng/ml Bovine viral diarrhea virus-1a Serum titers, log < Seroconversion, % < Infectious bovine rhinotracheitis virus Serum titers, log a 0.88b 0.79b < Seroconversion, % < Parainfluenza-3 virus Serum titers, log < Seroconversion 2, % day < day a-b Within a row, means without a common superscript differ (P 0.05). 1 Steers were vaccinated on days 0 on d Means covariate-adjusted to the respective measurements obtained on day 0 (P 0.02) Florida Beef Research Report

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119 Intake and Ruminal Fermentation Parameters of Beef Steers Consuming Bahiagrass Hay Treated with Calcium Oxide F. M. Ciriaco 1, D. D. Henry 1, and N. DiLorenzo 1 Synopsis Improving the digestibility of forages has been a longstanding goal for beef cattle nutritionists and agronomists, especially in the southeastern U.S., where forages comprise the main feed resource in livestock systems. The use of chemical compounds that are safe for cattle consumption and can disrupt the cellulose linkages is a potential approach to improve the digestibility of forages. Summary To determine the effects of calcium oxide (CaO) treated bahiagrass hay on intake and ruminal fermentation parameters of beef steers, 9 ruminally cannulated Angus crossbred steers [1,089 ± 320 lb body weight (BW)] were used in a triplicated 3 3 Latin square design. In each of the three periods, steers were housed at the University of Florida Feed Efficiency Facility (FEF; 3 steers/pen), where daily individual intake was recorded via the GrowSafe system. The steers had ad libitum access to bahiagrass hay and were randomly assigned to one of three treatments: 1) untreated dry bahiagrass hay (n = 8; DH); 2) bahiagrass hay treated with 8.9% CaCO [dry matter (DM) basis] + water (to 50% DM; n = 9; CC); or 3) bahiagrass hay treated with 5% CaO (DM basis) + water (to 50% DM; n = 8; CO). Starting at 0700 h (0 h), ruminal fluid was collected every 3 h for 24 h, and immediately after each collection, ruminal ph was measured. Ruminal fluid was analyzed for concentrations of volatile fatty acids (VFA) and NH 3-N. Average DM intake (DMI) in lb/d (P = 0.76) and percent of BW (P = 0.67) were not affected by treatment. Ruminal concentrations of NH 3-N tended (P = 0.06) to be reduced in steers consuming CO. A treatment effect (P<0.001) was observed for average ruminal ph, where steers consuming CO had the greatest ph when compared to DH and CC. No treatment effects (P>0.05) were observed for molar proportions of acetate, propionate, or branched-chain VFA (BCVFA); however, butyrate molar proportion was lower (P = 0.002) in steers consuming CO and CC, when compared to DH. Moreover, no treatment effect (P = 0.64) was observed for acetate to propionate ratio; however, total VFA concentration was lower (P = 0.02) in steers consuming CO, when compared to DH and CC. The consumption of bahiagrass hay treated with CaO 3 may reduce ruminal fermentation of beef steers as indicated by decreased total VFA concentration without altering DMI. Introduction Beef cattle nutritionists and forage breeders have endeavored to increase the digestibility of forages for several years. Small improvements have been made through breeding, attempting to reduce the fibrous components lignin and cellulose in forages; however, the main function of these compounds in nature is to provide structure and support to plants, making it difficult to improve the digestibility without reducing forage yield. An approach that has been little explored to improve the digestibility of forages by cattle is the use of chemical compounds that are both safe for cattle consumption and have the ability to disrupt the cellulose linkages. The treatment of cellulose fibers with alkali is common in the paper making process to separate the cellulose fibers from lignin. Early research by animal scientists in the 1970s indicated potential improvements in fiber digestion when 5% sodium hydroxide was added to low quality forages on a DM basis (Klopfenstein et al., 1972). This area of research was discontinued when the focus of animal scientists turned to the improvement of digestibility in high-grain diets. Nowadays, several advances in forage conservation and machinery create an opportunity to chemically treat and store forages and byproducts at a reduced cost to be used as an alternative cattle feed Florida Beef Research Report

120 The conditions in the southeastern U.S. are ideal to grow large quantities of forage; however, some of the primary forages fed in this region of the country, such as bahia or even bermudagrasses, are of medium to low-quality, due to elevated fiber contents. These characteristics could be overcome by using chemical treatment. Nevertheless, the use of alkali in forages grown in the southeastern U.S. has never been evaluated. The objectives were to determine the effects of calcium oxide treated bahiagrass hay on intake and ruminal fermentation parameters of beef steers. Materials and Methods The study was conducted at the FEF located at the University of Florida North Florida Research and Education Center in Marianna, FL. Calcium oxide was obtained from Mississippi Lime (St. Louis, MO). A total of nine ruminally cannulated Angus crossbred steers (weighing average 1,089 ± 320 lb) were used in the study in a triplicated 3 3 Latin square design. Each of the three experimental periods consisted of 28 d, with 14 d of adaptation, 7 d of sample collection and 7 d of washout period, where a common diet of untreated bahiagrass hay was fed to all steers. On d 0, steers were weighed and randomly assigned to one of three treatments: 1. DH = untreated dry bahiagrass hay 2. CC = bahiagrass hay treated with 8.9% CaCO 3 (DM basis) + water (to 50% DM) 3. CO = bahiagrass hay treated with 5% CaO (DM basis) + water (to 50% DM) Bahiagrass hay was chopped using a Tub Grinder (Haybuster, Jamestown, ND) and, for the treatments CC and CO, placed in a feed wagon, where CaCO 3 or CaO was added at their corresponding amounts. Based on weight, and using a fire hose, water was added to both treatments to achieve a 50% DM content. No difference in digestibility is expected to occur by treating the hay with CaCO 3; thus the purpose of treatment was just an attempt to provide the same amount of Ca in both CC and CO treatments. After homogenization, the treated hay from both CC and CO was baled into square bales, which were placed individually into commercial plastic trash bags and vacuumed sealed in an attempt to achieve an anaerobic environment for incubation. The hay for the DH treatment was also square baled but not placed into plastic bags. The treated hay remained into bags for at least 7 d before feeding but no longer than 14 d to avoid molding. All steers were housed in pens at the FEF (three steers/pen) and had ad libitum access to water and their corresponding treatments. After the 14-d adaptation to treatments and facility, steers were weighed and collection of daily feed intake data started. Each pen at the FEF was equipped with two GrowSafe tubs (GrowSafe System Ltd., Airdrie, Alberta, Canada) to measure DMI on a lb/d and % of BW basis. On d 14, for 24 h (every three hours), collections of ruminal fluid were performed. Right after collection of ruminal fluid, ph was measured and acidified samples were stored in the freezer for further analysis of VFA and NH 3-N. In the lab, VFA were measured in the ruminal fluid via gas chromatography while NH 3-N concentrations were measured following the phenol-hypochlorite technique. All procedures for sample collections and analyses were performed as described by Ciriaco et al. (2016) Data were analyzed as repeated measures using the MIXED procedure of SAS (SAS Institute Inc., Cary, NC). Steer was considered the experimental unit and the model included the fixed effects of treatment, time, treatment time, square, and period. Animal within square and animal within treatment were included as random effects. Significance was determined at P 0.05 and tendencies were considered when 0.05<P Results Average daily DMI is presented in Figure 1. Steer DMI, either as lb/d (A; P = 0.76) or % of BW (B; P = 0.67), was not affected by treatment. Ruminal fermentation parameters are presented in Table Florida Beef Research Report

121 Ruminal concentrations of NH 3-N tended (P = 06) to be reduced in steers consuming bahiagrass hay treated with CaO (CO). Regardless of treatment, concentrations of NH 3-N observed in this study were considered lower than the minimum recommended for maximized microbial growth (3.57mM; Satter and Slyter, 1974), indicating that these steers might have not been consuming sufficient amounts of N; thus, some kind of protein supplementation could have been beneficial. A treatment effect (P<0.001) was observed for average ruminal ph, where steers consuming bahiagrass treated with CaO (CO) had the greatest ph when compared to those consuming untreated dry hay (DH) and hay treated with CaCO 3 (CC). Calcium oxide is a strong alkali, with an average ph reaching as high as 11. Since CaCO 3 does not have a buffering capacity and was only added to provide the same amount of Ca present in the CO treatment, it was expected that CO would promote some buffering in the rumen; thus, increasing its ph. Ruminal VFA profile is presented in Table 2. No treatment effects (P>0.05) were observed for molar proportions of acetate, propionate, or BCVFA; however, butyrate molar proportion was lower (P = 0.002) in steers consuming hay treated with CaO (CO) and CaCO 3 (CC), when compared to those consuming untreated dry hay (DH). Moreover, no treatment effect (P = 0.64) was observed for acetate to propionate ratio; however, total VFA concentration was lower (P = 0.02) in steers consuming hay treated with CaO (CO), when compared to those consuming DH and CC leading to the conclusion that bahiagrass hay treated with 5% CaO may reduce ruminal fermentation as indicated by decreased total VFA concentration without altering DMI. Acknowledgements The authors would like to thank the Florida Cattlemen Association for providing funding to support this study through the Florida Cattle Enhancement Board. Literature Cited Ciriaco et al J. Anim. Sci. 94: 9: Klopfenstein et al J. Anim. Sci. 35: Satter and Slyter Br. J. Nutr. 32: Florida Beef Research Report

122 ADMI, lb/d DH CC CO B 1.5 DMI, % BW DH CC CO Figure 1. Effects of bahiagrass hay treated or not with calcium oxide (CaO) on dry matter intake (DMI) of beef steers. A: DMI presented as lb/d; no effects of treatment observed (P = 0.76); B: DMI presented as % of body weight (BW); no effects of treatment observed (P = 0.67). DH: untreated dry bahiagrass hay fed ad libitum; CC: bahiagrass hay treated with 8.9% CaCO3 (DM basis) + water (to 50% DM) fed ad libitum; CO: bahiagrass hay treated with 5% CaO (DM basis) + water (to 50% DM) fed ad libitum Florida Beef Research Report

123 Table 1. Effects of bahiagrass hay treated or not with calcium oxide (CaO) on daily average ruminal fermentation parameters 1 of steers provided ad libitum intake. Treatment 2 P-value 4 Item 1 DH CC CO SED 3 TRT TIME TRT x TIME NH 3-N, mm < Ruminal ph 6.67 a 6.75 a 7.06 b < < a,b Within a row, means with different superscripts differ; treatment effect, P Ruminal fluid samples were collected every 3 h for 24 h. 2 D: Untreated dry bahiagrass hay, n = 8; CC: Bahiagrass hay treated with 8.9% CaCO 3 (DM basis) + water (to 50% DM), n = 9; CO: Bahiagrass hay treated with 5% CaO (DM basis) + water (to 50% DM), n = 8. 3 SE of treatment differences. 4 Observed significance levels for treatment (TRT) and TIME effects, and for their interaction (TRT x TIME). Table 2. Effects of bahiagrass hay treated or not with calcium oxide (CaO) on ruminal VFA profile 1 of steers provided ad libitum intake. Treatment 2 P-value 4 Item 1 DH CC CO SED 3 TRT TIME TRT x TIME VFA, mol/100 mol Acetate < Propionate < Butyrate 7.7 b 6.8 a 6.6 a < BCVFA < Total VFA, mm 61.2 b 61.7 b 53.5 a < A:P < a,b Within a row, means with different superscripts differ, P< Ruminal fluid and blood samples were collected every 3 h for 24 h. 2 D: Untreated dry bahiagrass hay, n = 8; CC: Bahiagrass hay treated with 8.9% CaCO 3 (DM basis) + water (to 50% DM), n = 9; CO: Bahiagrass hay treated with 5% CaO (DM basis) + water (to 50% DM), n = 8 3 SE of treatment differences. 4 Observed significance levels for treatment (TRT) and TIME effects, and for their interaction (TRT x TIME). 5 BCVFA = Branched chain VFAs: isobutyrate + isovalerate + 2 methylbutyrate. 6 Acetate to propionate ratio Florida Beef Research Report

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125 Effects of Timing of Vaccination Relative to Weaning and Post-weaning Supplementation Frequency on Growth and Immunity of Growing Beef Calves G. M. Silva 1, J. Ranches 1, and P. Moriel 1 Synopsis Pre-weaning vaccination associated with reduced post-weaning frequency of supplementation caused the greatest reduction on calf growth performance. However, post-weaning vaccination and daily concentrate supplementation alleviated inflammatory response and improved humoral immune response compared to pre-weaning vaccination and reduced post-weaning frequency of supplementation. Summary We evaluated the impact of pre- vs. post-weaning vaccination associated with different post-weaning frequency of energy supplementation (daily vs. 3x weekly) on growth and immunity of beef calves. At 14 days before weaning (day -14), 48 Angus-crossbred calves (24 steers and 24 heifers; 537 ± 73 lb; 19 ± 20 days of age) were stratified by body weight, age, and randomly assigned to receive vaccinations against bovine viral diarrhea virus (BVDV-1a) and parainfluenza-3 (PI-3) on days -14 and 0 (PRE) or days 7 and 21 (POS), relative to weaning. On day 7, calves were stratified by vaccination scheme, and randomly assigned to receive similar weekly amount of concentrate dry matter supplementation (1% of body weight multiplied by 7 days) that was divided and offered either daily (7X) or 3 times weekly (3X; Monday, Wednesday, and Friday) until day 43. Effects of timing of vaccination frequency of supplementation were not detected for any measurement of calf average daily gain, total dry matter intake, and feed efficiency, except for overall average daily gain from days -14 to 43. Post-weaning total dry matter intake and feed efficiency did not differ among treatments. Pre-weaning vaccination increased overall plasma concentrations of cortisol, tended to increase overall plasma concentrations of haptoglobin, and decreased serum PI-3 titers on day 43 compared to post-weaning vaccination. Decreasing the frequency of supplementation tended to increase post-vaccination plasma cortisol concentrations and reduce overall serum BVDV-1a titers. Hence, pre-weaning vaccination combined with reduced post-weaning frequency of supplementation caused the greatest reduction on calf growth performance. Post-weaning vaccination and daily concentrate supplementation alleviated inflammatory response and improved vaccine response compared to pre-weaning vaccination and reduced post-weaning supplementation frequency. Introduction Preconditioning programs have been shown to reduce post-weaning stress, incidence of bovine respiratory disease (BRD; Duff and Gaylean 2007), and improve growth performance of calves during feedlot phase (Roeber et al., 2001). However, supplements provided during preconditioning phase can increase total production costs associated with labor, fuel, and equipment (Cooke et al., 2008). Decreasing the frequency of supplementation from daily to 3 times weekly can reduce feeding costs during preconditioning, but also impaired post-weaning growth performance and vaccine-induced immune response of beef steers (Artioli et al., 2015). These negative impacts of reduced frequency of energy supplementation are associated with an exacerbation of the acute phase response (APR) elicited by vaccination during preconditioning. Although APR is an essential early defense mechanism in response to cellular injury (Eckersall and Conner, 1988), nutrient demand is increased (Reeds and Jahoor, 2001), and nutrients partitioned away from growth to support the immune response (Reeds et al., 1994), leading to reduced calf growth performance and feed efficiency (Moriel et al., 2016). We hypothesized that administering the vaccination against respiratory pathogens during pre-weaning rather than post-weaning phase could be a strategy to overcome the negative impacts of reducing the frequency of energy supplementation on growth and immunity of preconditioning beef calves. Therefore, Florida Beef Research Report

126 we evaluated the effects of timing of vaccination against respiratory pathogens and frequency of energy supplementation on measurements of growth immunity of beef calves during a 43-day preconditioning period. Materials and Methods The study was conducted from October to December 2016 at the Mountain Research Station, Waynesville, NC. Forty-eight Angus crossbred calves were stratified by body weight and age, and randomly assigned, in a 2 2 factorial design to receive pre- (PRE; days -14 and 0) or post-weaning (POS; days 7 and 21) vaccinations against BRD pathogens with different post-weaning frequency of energy supplementation (7X or 3X weekly). From days 0 to 43, all calves received free choice access to ground tall fescue hay and similar weekly supplementation of a 50:50 soybean hulls pellets and corn gluten pellets supplement (weekly supplement dry matter intake = 1% of body weight multiplied by 7 days). Individual calf body weight was measured before feeding on days -14 and 43, following 12 hours of feed and water withdrawal. Blood samples were collected to evaluate serum antibody titers against BVDV-1a, and PI-3 viruses and plasma concentrations of haptoglobin and cortisol. Except for seroconversion, all data were analyzed as a 2 2 factorial design using the MIXED procedure of SAS (SAS Institute Inc., Cary, NC, USA, version 9.4). Pen was considered the experimental unit and the model included the fixed effects of timing of vaccination, frequency of supplementation, and timing of vaccination frequency of supplementation. Random effects included sex, calf (pen) and pen (vaccination frequency). Significance was determined at P 0.05 and tendencies were considered when 0.05<P Results Interaction effect between vaccination frequency of supplementation was not detected for any variable in this study (P 0.12), except for overall average daily gain from days -14 to 43 (P = 0.04). Overall average daily gain tended to be less for PRE-3X calves compared to POS-7X and PRE-7X calves (P = 0.09), and was less for PRE-3X calves compared to POS-3X (P = 0.006; 1.32, 1.54, 1.54, and 1.71±0.08 lb/day for PRE-3X, PRE-7X, POS-7X, and POS-3X calves, respectively). Post-weaning total dry matter intake and feed efficiency from days 0 to 43 did not differ among treatments (P 0.11; data not shown). As shown in Table 1, pre-weaning vaccination increased overall plasma concentrations of cortisol (P<0.0001), tended to increase overall plasma concentrations of haptoglobin (P = 0.10), and decreased serum PI-3 titers on day 43 compared to post-weaning vaccination (P<0.0001). Also, decreasing the frequency of supplementation tended (P = 0.10) to increase post-vaccination plasma cortisol concentrations and reduce overall serum BVDV-1a titers. Hence, pre-weaning vaccination in combination with reduced post-weaning frequency of supplementation (3 times weekly) caused the greatest reduction on overall calf growth performance. Post-weaning vaccination and daily concentrate supplementation alleviated inflammatory response and improved antibody production compared to pre-weaning vaccination and reduced post-weaning supplementation frequency. Literature cited Artioli, L. F. A., et al J. Anim. Sci. 93: Cooke, R. F., et al J. Anim. Sci. 86: Duff, G. C., and M. L. Galyean J. Anim. Sci. 85: Eckersall, P. D., and J. G. Conner Vet. Res. Communic. 12: Moriel, P., et al J. Anim. Sci. 94: Reeds, P. J., et al. J. Nutr. 124: Reeds, P. J., and F. Jahoor Clin. Nutr. 20: Roeber, D. L., et al Prof. Anim. Sci. 17: Florida Beef Research Report

127 Table 1. Plasma and serum measurements calves assigned to receive pre- (days -14 and 0; PRE) or post-weaning (days 7 and 21; POS) vaccination against pathogens associated with respiratory disease, and then, post-weaning concentrate supplementation provided 3 (3X; Monday, Wednesday, and Friday) or 7 (7X; daily) times weekly during a 43-day preconditioning period. Timing of vaccination Supplementation frequency P-value Timing of vaccination 3X 7X SEM P-value Supplementation frequency Item PRE POS SEM Overall plasma concentrations Cortisol, ng/ml < Haptoglobin, mg/ml Parainfluenza-3 virus Serum titers, log Positive seroconversion, % Bovine viral diarrhea virus 1a Serum titers, log Positive seroconversion, % Florida Beef Research Report

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129 The Effects of Biweekly Administration of Recombinant Bovine Somatotropin During the First Trimester on Fetal and Placental Development in Beef Heifers C. D. Sanford 1, N. Oosthuizen 1, P. L. P. Fontes 1, L. B. Canal 1, K. A. Vonnahme 2, C. O. Lemley 3, N. DiLorenzo 1, and G. C. Lamb 4 Synopsis The biweekly administration of 500 mg of recombinant bovine somatotropin from fixed time artificial insemination to day 57 did not affect overall fetal growth when assessed at d 77, but the extraembryonic parameters data expressed a potential benefit to placental function in gestating beef heifers. Summary A total of 97 Angus-based crossbred beef heifers were exposed to the 7-day CO-Synch + CIDR estrus synchronization control protocol and then artificially inseminated. At fixed-time artificial insemination (TAI; d 0) heifers were randomly assigned to receive one of two treatments: single subcutaneous injection with 500 mg of bst in the neck at TAI and then biweekly until day 57 of the experiment (BST; Figure 1); or an untreated control (CONT). Blood samples were collected on days -0, 22, 50, and 64 relative to TAI for analysis of plasma concentrations of IGF-1. Heifer body weight (BW) was recorded on d -9, -3, 0, 15, 22, 29, 43, 50, 57, 64, and 77. Pregnancy was determined via transrectal ultrasonography on d 29 and d 64 after TAI. On day 85 after TAI heifers were harvested and a subset of pregnant heifers (n = 7 for BST, n = 5 for CONT) were retained for assessment of fetal and placental characteristics. At time of harvest complete gravid reproductive tracts and liver tissue from the dams were collected for analysis. Specific fetal measurements assessed were: brain weight, crown-to-nose length, crown-to-rump length, heart girth, fetal BW, eviscerated BW, liver weight, and umbilical cord diameter; whereas extraembryonic measurements were: fetal fluid volume, fetal membrane weight, placentome weights, and placentome number. In addition, maternal tract parameters of gravid uterine weight, empty uterine weight, ovarian weight, and corpus luteum weight were recorded. Mean change in BW (158 lb) and ADG (2.09 lb/d ± 0.59) of the heifers from TAI to d 77 did not differ between treatments (P>0.05). Likewise, no differences were detected between treatments with regards to carcass quality grade, carcass yield, or carcass weight. Mean plasma concentrations of IGF-1 were greater (P<0.001) in BST ( ± 27.7 ng/ml) treated than CONT ( ± 32.8 ng/ml) heifers. Mean placental weight (66.46 g), fetal membrane weight (0.256 kg), uterine weight (1.42 kg), as well as ovarian and corpus luteum weights (15.1 g and 4.8 g, respectively) did not differ (P>0.05) between treatments. Similarly, fetal crown-to-rump length, fetal weight, heart girth, and liver weight did not differ between treatments (P>0.05). However, extraembryonic samples collected from heifers receiving bst (521.6 ± 22.9 g) resulted in greater (P = 0.03) volume of fetal fluid compared to CONT heifers (429.6 ± g). There was also a tendency for BST heifer reproductive tracts to have fewer placentomes (P = 0.08) and greater umbilical diameter (P = 0.09) than CONT heifers. In conclusion, administration of bst during the first trimester of gestation increased plasma concentrations of IGF-1, which resulted in greater extraembryonic fluid, a decreased quantity of placentomes, and greater umbilical diameter; however, failed to alter fetal development. 1 North Florida Research and Education Center, University of Florida, Marianna, FL 2 Department of Animal Sciences, North Dakota State University, Fargo, ND 3 Department of Animal and Dairy Science, Mississippi State University, Mississippi State, MS 4 Department of Animal Science, Texas A&M University, College Station, TX Florida Beef Research Report

130 Introduction Fetal and placental development research is critical in order to gain knowledge of how developmental programming can be used to aid in producing healthy, efficient livestock with superior longevity. Maternal stress research such as nutrient restriction or elevated nutritional programs has been reported to have long-term impacts on the offspring (Reynolds and Redmer, 1995, 2001; Redmer, 2004). There has also been research examining the effects of blood flow, with reports that placental nutrient transport efficiency is directly related to uteroplacental blood flow (Reynolds and Redmer, 1995). Additionally, there has been research conducted examining how placental function stimulation or even realimentation can lead to a decrease in morbidity and mortality as well as suboptimal offspring growth performance (Vonnahme, 2012). Exponential growth of the fetus and placenta occurs during the second and third trimester of gestation. However, it has been reported that these pregnancy outcomes are dependent on the growth of the uteroplacental vascular beds that occur in the first half of the pregnancy (Meschia, 1983; Reynolds and Redmer, 1995). But more research is needed to better understand the critical timepoints of fetal and placental susceptibility to developmental programming and how food animal producers can utilize this information. Somatotropin, or growth hormone (GH), is a naturally occurring protein hormone in humans and animals that is produced by the anterior pituitary. Additionally, GH can either cause a direct response or mediates a response through the induction of IGF-1 to regulate body growth through the effects IGF-1 on bone, adipose and muscle. The primary location for GH receptors is the liver, where GH binding increases synthesis and secretion of IGF-1 (Le Roith, 2001). One consideration that our team had was how a recombinant bovine somatotropin product (bst) that is commonly used in the dairy industry would effect fetal and placental development in gestating beef heifers. Thus, this study was designed to evaluate how bst would effect fetal and placental development when administered during the first trimester in gestating beef heifers. The goal was to provide further information and understanding of how the somatotropic axis components of GH and IGF-1 may stimulate conceptus development. It was hypothesized that bst administration concurrent with TAI would initially increase concentrations of IGF- 1 in blood plasma, and that continued biweekly bst administration would sustain increased plasma concentrations, potentially resulting in altered fetal and placental development. Materials and Methods An initial group of 97 Angus-based, crossbred beef heifers at the North Florida Research and Education Center in Marianna, FL were enrolled in the study. All heifer were exposed to the 7-day CO-Synch + CIDR estrus synchronization control protocol followed by fixed-time artificial insemination (TAI; d 0). Heifers were then randomly assigned to receive one of two treatments: single subcutaneous injection with 500 mg of bst (Posilac, sometribove zinc, Elanco Animal Health, Greenfield, IN) in the neck at TAI and then 500 mg of bst biweekly until day 57 of the experiment (BST; Figure 1); or an untreated control (CONT). Blood samples were collected on days -0, 22, 50, and 64 relative to TAI to determine the concentrations of plasma IGF-1. An immunoassay system (Immulite 1000 Version 5.22; Siemens Healthcare Diagnostics, Malvern, PA) was used to perform the plasma IGF-1 concentrations analysis. Body weight of heifers was recorded on d -9, -3, 0, 15, 22, 29, 43, 50, 57, 64, and 77. Pregnancy was determined via transrectal ultrasonography (Ibex portable ultrasound, 5.0-MHz linear multi-frequency transducer, Ibex, E.I. Medical Imaging, Loveland, CO) on d 29 and d 64 after TAI. On day 84, all heifers were transported to a commercial abattoir for harvest. At harvest (d 85) a subset of pregnant heifers (n = 7 for BST, n = 5 for CONT) were retained for assessment of fetal and placental characteristics. Complete gravid reproductive tracts and dam liver tissue were collected. Specific fetal measurements assessed were: brain weight, crown-to-nose length, crown-to-rump length, heart girth, fetal BW, eviscerated BW, liver weight, and umbilical cord diameter; whereas, extraembryonic measurements were: fetal fluid volume, fetal membrane weight, placentome weights, and placentome number. In addition, maternal tract Florida Beef Research Report

131 parameters of gravid uterine weight, empty uterine weight, ovarian weight, and corpus luteum weight were recorded. On day 89, carcass quality grade, carcass yield, and carcass weight data were obtained. Data was analyzed as a completely randomized design and heifer was considered the experimental unit. The SAS (version 9.4; SAS/STAT, SAS Inst. Inc., Cary, NC) statistical package was used for all statistical analyses. All continuous data was analyzed by PROC MIXED. Additionally, heifer BW and plasma concentrations of IGF-1 were analyzed as repeated measures. The model included the fixed effects of treatment, day, and treatment x day interaction. Statistical significance was declared at P 0.05, while a statistical tendency was declared at 0.05<P<0.10. Results Mean placental weight (66.46 g), fetal membrane weight (0.256 kg), uterine weight (1.42 kg), as well as ovarian and corpus luteum weights (15.1 g and 4.8 g, respectively) did not differ (P>0.05) between treatments (Table 1). Similarly, fetal crown-to-rump length, fetal weight, heart girth, and liver weight did not differ between treatments (P>0.05). However, extraembryonic samples collected from heifers receiving bst (521.6 ± 22.9 g) resulted in greater (P = 0.03) volumes of fetal fluid compared to CONT heifers (429.6 ± g). There was also a tendency for BST heifer reproductive tracts to have fewer placentomes (P = 0.08) and greater umbilical diameter (P = 0.09) than CONT heifers. Mean concentrations of IGF-1 were greater (P<0.001) in BST ( ± 27.7 ng/ml) treated than CONT ( ± 32.8 ng/ml) heifers (Figure 2). Mean change in BW and ADG (0.95 kg ± 0.27) of the heifers from TAI to d 77 did not differ between treatments (P>0.05). Likewise, no differences were detected between treatments with regards to heifer carcass quality grade, carcass yield, or carcass weight. Therefore, although concentrations of IGF-1 were increased in heifers that received biweekly administration of bst from TAI to day 57 of gestation, overall fetal development parameters did not differ between treatments. However, in regards to extraembryonic development due to stimulation by the GH and IGF system there was greater fetal fluid volume, a tendency for increased umbilical diameter, and decreased placentome number in the BST heifers. Acknowledgements Together the authors wish to thank the Florida Cattle Enhancement Fund DACS for providing the research funding; Zoetis Animal Health (Parsippany, NJ) for their donation of synchronization products; as well as FPL Food, LLC (Augusta, GA) for allowing us to collect the samples in their commercial abattoir. Literature Cited Le Roith, D Endocrinol. Rev. 22: Meschia, G Am. Physiol. Soc Redmer, D. A., et al Domest. Anim. Endocrinol. 27: Reynolds, L. P., and D. A. Redmer J. Anim. Sci. 73: Reynolds, L. P., and D. A. Redmer Biol. Reprod. 64: Vonnahme, K. A., and C. O. Lemley Reprod. Fertil. Dev. 24: Florida Beef Research Report

132 Table 1. Extraembryonic, maternal, and fetal development measurements in gestating beef heifers treated with recombinant bovine somatotropin Treatment 1 CONT BST SEM P-value 2 Fetal membrane weight, kg No. of placentomes Placental weight, g Fetal fluid, ml Gravid uterine weight, kg Empty uterine weight, kg Ovarian weight, g Corpus luteum weight, g Brain weight, g Crown-to-nose length, cm Crown-to-rump length, cm Fetal BW, g Heart girth, cm Liver weight, g Umbilical cord diameter, mm Angus based heifers were randomly assigned to either receive the BST (n = 7) treatment, biweekly subcutaneous injections of 500 mg of recombinant bovine somatotropin (bst) in the neck, or to not receive bst (n = 5) in addition to being exposed to the 7-day CO-Synch + CIDR estrus synchronization protocol and then artificial inseminated. 2 Statistical significance was declared at P 0.05, while a statistical tendency was declared at 0.05<P<0.10. Figure 1. Schematic of treatments. All heifers received an injection of gonadotropin-releasing hormone (GnRH), and a controlled internal drug release (CIDR; 1.38 g of progesterone) insert on d -9; an injection of prostaglandin F 2α (PG) at CIDR removal on d -3; and a second injection of GnRH concurrent with fixed-time AI (TAI) on d 0. Heifers were randomly assigned to receive one of two treatments: 500-mg of bovine somatotropin (bst) by a single subcutaneous injection in the neck at TAI and then biweekly to d 57 (BST); or an untreated control (CONT). Blood samples (Blood) were collected on d 0, 22, 50, and 64. Pregnancy status was determined by transrectal ultrasonography (US) on d 29 and 64 after TAI. Heifers were transported to a commercial abattoir and a subset of pregnant heifers (n = 7 for BST and n= 5 for CONT) were retained to evaluate fetal and placental characteristics. At time of harvest on d 85 complete gravid reproductive tracts and liver tissue were collected for analysis Florida Beef Research Report

133 Concentration of IGF-1, ng/ml CONT BST * * * Day relative to TAI Figure 2. Results for plasma concentrations of insulin-like growth factor 1 (IGF-1) from blood sample analysis of gestating beef heifers. Heifers in the BST treatment group received 500-mg of bovine somatotropin (bst) biweekly from TAI to d 57 while the CONT heifers did not. *Effect of treatment (P<0.001); treatment day interaction (P<0.001) Florida Beef Research Report

134 Florida Beef Research Report

135 Pre-Weaning Injections of Bovine Somatotropin Enhanced Puberty Attainment and Calving Rates of Bos Indicus-Influenced Beef Heifers M. B. Piccolo 1, G. M. Silva 1, R. F. Cooke 1, G. C. Lamb 1, J. Vendramini 1, J. D. Arthington 1, and P. Moriel 1 Synapsis The objective of this study was to determine if administration of recombinant bovine somatotropin (bst) to beef females between 135 and 162 days of age had the potential to enhance puberty achievement and therefore enhance overall reproductive success. Three 14-d apart injections of 250 mg of bst, during this period of the reproductive axis development of heifers, enhanced reproductive performance but it did not affected BW. Summary This 3-year study evaluated the effects of pre-weaning bst injections on growth and reproductive performance of beef heifers. Ninety suckling Brangus crossbred heifers (324 ± 45 lb; Age=134 ± 11 days) were stratified by body weight and age, and randomly assigned to 1 of 2 treatments (15 heifers/treatment/year), which consisted of subcutaneous injection of saline solution (SAL; 5 ml; 0.9% saline) or bst (250 mg) on d 0, 14, and 28. Cow-calf pairs were allocated to 4 bahiagrass pastures (7-8 pairs/pasture/year) from day 0 until weaning (day 127). Full body weight and blood samples from jugular vein were collected on days 0, 14, 28, and 127. From day 127 to 346, heifers were grouped by treatment and allocated to bahiagrass pastures (1 pasture/treatment/year) and fed soybean hull-based concentrate at 1.1% of body weight (dry matter basis). Blood samples were collected every 9 to 10 days from day 127 to 346 to determine plasma concentrations of progesterone and assess puberty attainment. Injections of bst enhanced overall plasma IGF-1 concentrations and average daily gain (ADG) during the first 42 days of experiment (days 0 to 42). However, weaning weight did not differ (P = 0.25) between SAL and BST heifers (575 vs. 570 ± 6.2 lb, respectively). Post-weaning ADG (days 127 to 346) also did not differ (P=0.61) between SAL and bst heifers (0.66 vs. 0.62±0.05 lb). However, a greater percentage of bst heifers achieved puberty at the beginning of the breeding season compared with SAL heifers (40 vs. 20 ± 6.3%; P 0.03). Animals in the bst group also had greater (P 0.05) pregnancy and calving rates (81.9 vs. 68.8±6.2%, and 90.0 vs. 53.3±7.3, respectively) compared to SAL heifers. However, calving distribution did not differ between treatments (P 0.15). Three injections of 250 mg of bst at 14-day intervals, between 135 and 163 days of age, improved reproductive performance of Brangus replacement beef heifers during their first breeding season. Introduction Metabolic imprinting or programming is the concept that nutrition during first months of life may permanently change the physiology and future performance of the offspring (Lucas, 1991; Lucas, 1994; Moriel et al., 2014). Thus, identifying nutritional strategies that can enhance pre-weaning heifer growth performance, and subsequently improve future reproductive performance may provide unique opportunities to optimize feed resources and increase the profitability of cow-calf operations. Previous studies from our group (Moriel et al., 2014) showed that heifer calves weaned at 70 days of age and feed a high concentrate diet for 90 days had greater percentages of puberty achievement at the beginning of the breeding season compared to heifers kept with their dams and normally weaned at 240 days of age. Those authors also observed that age at puberty was decreased in average 0.59 days for every 1 ng/ml increase on pre-weaning plasma concentrations of IGF Florida Beef Research Report

136 Plasma concentrations of IGF-I are positively associated with body condition and nutrient intake; however, Bilby et al., (2004) enhanced plasma IGF-1 concentrations of dairy cows shortly after bst application and was able to keep plasma IGF-1 concentrations high using serial bst applications. Cooke et al., (2013) showed that circulating plasma IGF-1 concentration was positively associated with onset of puberty in heifers. Hence, strategies that can enhance plasma concentrations of IGF-1 and growth performance during the pre-weaning phase might benefit future reproductive performance of beef heifers. Therefore, we hypothesized that administration of bst to suckling beef heifer calves would cause metabolic imprinting effects leading to increased puberty achievement and pregnancy rates of replacement beef heifers. Materials and Methods Ninety suckling Angus x Brahman heifer calves were stratified by cow age, heifer body weight and age on day 0 (n = 30/year; body weight =324 ± 45 lb; age=134 ± 11 days), and randomly assigned to 1 of 2 treatments, which consisted of 3 subcutaneous injections of saline solution or sometribove zinc (bst; Posilac, Elanco, Greenfield, IN) administered 14 days apart. Hence, treatments consisted of heifers receiving an injection of 5 ml of a 0.9% saline solution (SAL) or 250 mg of somatotropin (bst) on days 0, 14, and 28. Cow-calf pairs were allocated to 1 of 4 bahiagrass pastures (7 to 8 cow-calf pairs/pasture; 3 to 4 pairs/treatment/pasture) and managed similarly until weaning (day 127). All animals had free choice access to water and a complete trace mineral and vitamin supplement throughout the study. Immediately after weaning (day 127), heifers were stratified by treatment and allocated to 1 of 2 bahiagrass pastures (1 pasture/treatment/year) and were provided concentrate supplementation at 1.1% of body weight until the end of breeding season and of the study (day 346). Shrunk body weight was collected on days 0, 14, 28, 42 and 127 after 3 hours of feed and water removal. Blood samples were collected from all heifers on days 0, 14, 28, 42. Plasma concentrations of IGF-1 were determined by a commercial ELISA kit (Quantikine ELISA Human IGF1 Immunoassay, R&D Systems, Inc., Minneapolis, MN, USA). From day 127 to 346, blood samples were collected from jugular vein every 10 days and before daily supplementation to access plasma concentrations of progesterone and determine puberty achievement of heifers. Heifers were considered pubertal when 2 consecutive samples had plasma progesterone concentrations greater than 1.5 ng/ml (Cooke et al., 2007). Puberty attainment was declared on the first day of high plasma progesterone concentration. Shrunk body weight and hip height was collected monthly from day 127 to 346. All data was analyzed as a randomized block design using SAS (SAS Inst. Inc., Cary, NC; version 9.4). Heifers were considered the experimental unit. Heifer(treatment x year) and year were considered random effects in all analyses. The MIXED procedure was used to test the fixed effects of treatment on average daily gain, age and body weight at puberty, whereas GLIMMIX procedure was used to analyze as repeated measures the fixed effects of treatment, day of the study, and treatment x day on heifer body weight, plasma measurements, puberty achievement, and calving distribution. GLIMMIX procedure was also used to test the fixed effects of treatment on pregnancy and calving rates. Significance was set at P 0.05 and tendency at 0.05<P Results Pre-weaning bst injections increased overall plasma concentrations of IGF-1 during the first 42 days of experiment (Table 1). Likewise, bst applications improved heifer average daily gain between days 14 and 28 and days 0 to 42 (Table 1). However, these differences in plasma IGF-1 concentrations and average daily gain had no impact on body weight at weaning, even though SAL heifers experienced a greater average daily gain from day 42 until weaning compared to bst heifers (P 0.04; Table 1) Florida Beef Research Report

137 Post-weaning hip height change, average daily gain, and body weight at puberty did not differ between treatments (P 0.37; Table 2). Age at puberty was numerically greater for SAL heifers compared to bst heifers (P 0.15; Table 2). Despite the similar post-weaning growth performance, a greater percentage of heifers that received the bst treatment achieved puberty at the beginning of the breeding season (day 262) compared with SAL heifers (P 0.03; Figure 1). Also, bst heifers had greater pregnancy and calving rates compared to SAL heifers (P 0.05; Table 2). Calving distribution did not differ between treatments (P 0.41). Conclusion In summary, 3 injections of 250 mg of bst administered every 14 days from 135 and 162 days of age, increased plasma IGF-1 concentrations and average daily gain during the first 42 days of the study, and enhanced the percentage of pubertal heifers at the start of the breeding season. In addition, pre-weaning bst injections increased pregnancy and calving rates, without altering calving distribution. Further investigation, is needed to better understand the optimum dose and timing of administration of bst and its effects on growth and reproductive development and performance of beef cattle. Literature Cited Bilby et al J. Dairy Sci. 87: Cooke et al J. Anim. Sci. 85: Cooke et al J. Anim. Sci. 91: Lucas, A Ciba Found. Symp. 156: Lucas, A Arch. Dis. Child. 71: Moriel et al J. Anim. Sci. 92: Table 1. Heifer performance and plasma IGF-1 concentrations during pre-weaning phase. Treatment 1 Item Saline bst SEM P-value ADG, lb/day day 0 to day 14 to day 28 to day 0 to Plasma IGF-1, ng/ml day 42 to 127 (weaning) day 0 to 127 (weaning) Body weight weaning, lb Subcutaneous injections of bst or saline on days 0, 14 and Covariate-adjusted to plasma IGF-1 on day 0 (P<0.0001) Florida Beef Research Report

138 Percentage of Pubertal heifers, % SAL bst * ** * 262 Figure 1. Puberty achievement of Brangus heifers (breeding season = days 262 to 346). * P 0.05; **0.05<P Day of the study * 282 * Table 2. Post-weaning growth performance, pregnancy and calving rates of Bos indicus-influenced beef heifers treated with saline solution or bst during the pre-weaning phase. Treatment P-value Item SAL bst SEM Treatment x year Treatment Year ADG, lb/d day 127 to 262 (start breeding) day 127 to 346 (end breeding) Age at puberty, days Body weight at puberty, lb Pregnancy rate, % Calving rate, % Florida Beef Research Report

139 Administration of Recombinant Bovine Somatotropin Prior to Fixed-time Artificial Insemination and the Effects on Pregnancy Rates and Embryo Development in Beef Heifers N. Oosthuizen 1, P. L. P. Fontes 1, D. D. Henry 1, F. M. Ciriaco 1, C. D. Sanford 1, L. B. Canal 1, G. V. de Moraes 2, N. DiLorenzo 1, V. R. G. Mercadante 3, and G. C. Lamb 4 Synopsis The administration of recombinant bovine somatotropin to beef heifers at the initiation of a fixed-time artificial insemination (TAI) protocol increased plasma concentrations of IGF-1 at TAI; however, failed to enhance embryo/fetal development, and resulted in reduced pregnancy rates to TAI (PR/AI). Summary Four hundred and twelve Angus-based beef heifers were enrolled in a completely randomized design at 4 locations from January to July of All heifers were exposed to the 7-d CO-Synch + controlled internal drug release (CIDR) protocol where they received a 100-µg injection of GnRH and a CIDR insert on d -9, 25 mg of PGF 2α at CIDR removal on d -2, followed by a 100-µg injection of GnRH and fixed-time artificial insemination (TAI) 54 ± 2 h later on d 0. Within location, all heifers were randomly assigned to 1 of 2 treatments: 1) BST (n = 191); heifers received 650 mg of bst on d -9; or 2) CONTROL (n = 223); heifers did not receive bst on d -9. Blood samples were collected on d -9, 0, 28 and 60 to determine plasma concentrations of IGF-1. Pregnancy was diagnosed via transrectal ultrasonography between d 28 and 35 after TAI, and again at least 30 d after the end of the breeding season. Embryo development was assessed by measuring crown to rump length (CRL) on d 28, and fetal development was assessed by measuring crown-to-nose-length (CNL) on d 60. Concentrations of IGF-1 did not differ (P>0.05) between treatments on d -9, 28, and 60; however, concentrations of IGF-1 were greater (P<0.001) in BST treated heifers at TAI (372.4 ± 16.6 vs ± 16.6 ng/ml). Pregnancy rates to TAI (PR/AI) were greater (P = 0.03) in CONTROL compared with BST heifers (42.5 ± 4.0 vs ± 4.1%). No differences (P = 0.54) in CRL were determined on d 28 between CONTROL and BST heifers (9.1 ± 0.3 vs. 9.3 ± 0.3 mm, respectively). Additionally, no difference (P = 0.89) was determined in CNL between CONTROL and BST treatments. Final pregnancy rates did not differ (P = 0.70) between treatments. Introduction Growth hormone, or somatotropin (ST), is a protein hormone produced by the anterior pituitary, and once released, is transported to the liver where it induces the synthesis and secretion of IGF-1. Recombinant bovine ST (bst) is the biological equivalent to natural ST, and is commonly utilized in dairy operations to improve the productivity of lactating dairy cows (Hartnell et al., 1991). Administration of bst increases plasma concentrations of IGF-1 in cattle (Bilby et al., 2004; Cooke et al., 2013; Mercadante et al., 2016), and both bst and IGF-1 have been shown to affect reproduction (Lucy, 2000). The use of bst has improved ovarian follicular development, and increased the number of recruited follicles in lactating dairy cows (De La Sota et al., 1993; Kirby et al., 1997) and beef heifers (Gong et al., 1991, 1993, 1997); additionally, both bst and IGF-1 have been shown to stimulate embryonic development in bovines (Moreira et al., 2002). Bovine somatotropin supplementation enhanced conceptus development, reduced embryonic losses, and improved PR/AI in dairy cows 1 North Florida Research and Education Center, University of Florida, Marianna, FL 2 State University of Maringá, Maringá,Brazil/CNPq 3 Department of Animal Science, Virginia Tech, Blacksburg, VA 4 Department of Animal Science, Texas A&M University, College Station, TX Florida Beef Research Report

140 administered at TAI and again 14 d later (Ribeiro et al., 2014). Furthermore, the use of bst has been shown to increase PR/AI in lactating dairy cows (Moreira et al., 2000, 2001; Starbuck et al., 2006). Little information exists on the effects of bst administration at the initiation of an estrus synchronization protocol in beef heifers. Therefore, this study was performed to evaluate the effects of the administration of bst on the concentration of plasma IGF-1, embryo/fetal development, and pregnancy rates of beef heifers exposed to TAI. We hypothesized that an injection of bst at the initiation of a TAI protocol would increase concentrations of IGF-1 at TAI, and consequently enhance embryo/fetal development and improve PR/AI. Materials and Methods Four hundred and twelve Angus-based, crossbred beef heifers were enrolled in the experiment at 4 locations in 2 states (Florida and Virginia). All heifers were exposed to the 7-d CO-Synch + CIDR protocol where they received a 100-µg injection of GnRH and a CIDR (1.38 g of progesterone) insert on d -9, a 25-mg injection of PGF 2α at CIDR removal on d -2, and a 100-µg injection of GnRH and TAI 54 ± 2 h later on d 0. Within location, all heifers were randomly assigned to 1 of 2 treatments (Figure 1). 1) BST (n = 191); heifers were administered 650 mg of bst on d -9; or 2) CONTROL (n = 223); heifers did not receive bst on d -9. Estrus detection patches were utilized for estrus detection between CIDR removal and TAI. Heifers were considered to be in estrus when at least 50% of the rub-off coating was removed from the patch, or when the patch was absent. No less than 10 d after TAI, heifers were exposed to bulls for the remainder of the breeding season. Transrectal ultrasonography (5.0-MHz linear array transducer, Aloka 500V, Instrument of Science and Medicine, Vancouver, BC, Canada; or Ibex portable ultrasound, 5.0-MHz linear multi-frequency transducer, Ibex, E.I. Medical Imaging, Loveland, CO) was performed between 28 and 35 d after TAI to determine PR/AI. Embryo development was assessed by measuring CRL on d 28, and fetal development was determined by measuring crown-to-nose length CNL on d 60. A short ultrasound video was recorded at the first pregnancy diagnosis and the ideal position and orientation of the embryo was selected in a frame-by-frame manner in order to measure embryo CRL. A second video was recorded on d 60 and CNL was measured. The images were measured twice, each by a separate individual. The final CRL and CNL were calculated as the mean of both measurements. Follicle diameter was determined on d -9, -2, and 0 in a similar fashion to the CRL and CNL measurements. The length and width of the largest follicle was recorded, and the average of the 2 measurements was used to reflect the diameter of the follicle. Final pregnancy rates were determined by transrectal ultrasonography at least 30 d after the end of the breeding season. Blood samples were collected on d -9, 0, 28 and 60, to determine the concentrations of plasma IGF-1 at 1 location. Concentrations of plasma IGF-1 were determined with an immunoassay system (Immulite 1000 Version 5.22; Siemens Healthcare Diagnostics, Malvern, PA). The SAS (version 9.4; SAS/STAT, SAS Inst. Inc., Cary, NC) statistical package was used for all statistical analyses. Crown-to-rump length, CNL, PR/AI, and final pregnancy rates were analyzed using the GLIMMIX procedure of SAS. Plasma concentrations of IGF-1 and follicle diameter were analyzed as repeated measures using the MIXED procedure of SAS. Artificial insemination sire and AI technician were distributed evenly among treatments; therefore, these variables were not included in the models. Heifer was considered the experimental unit. Results A treatment day interaction (P<0.001) was detected on plasma concentrations of IGF-1 (Figure 2). Although plasma concentrations of IGF-1 were similar (P>0.05) between CONTROL and BST heifers on d -9 (223.1 ± 10.4 vs ± 10.4 ng/ml, respectively), plasma concentrations of IGF-1 differed Florida Beef Research Report

141 (P<0.05) on d 0 at TAI, where bst heifers had greater plasma concentrations of IGF-1 than CONTROL heifers (372.4 ± 16.6 vs ± 16.6 ng/ml). Furthermore, plasma concentrations of IGF-1 were similar between CONTROL and BST treatments on d 28 (P>0.05; 99.0 ± 16.9 vs ± 18.1 ng/ml) and d 60 (P>0.05; 84.2 ± 11.3 vs ± 12.1 ng/ml). Follicle diameter did not differ between treatments (P = 0.19), however, an effect of day was detected where follicles on d 0 had a greater (P<0.001) diameter than follicles on d -2 (12.59 ± 0.59 and ± 0.58 mm, respectively). No treatment day (P = 0.59) interaction was detected. Estrus response differed by location; however, was similar (P = 0.86) between CONTROL and BST treatments. No treatment location interaction was detected (P = 0.84). Pregnancy rates to TAI were reduced (P = 0.03) in heifers from the BST compared to the CONTROL treatment. Additionally, there was an effect of location (P<0.001) on PR/AI, which ranged from 20.8 to 46.2%. No treatment location interaction was detected (P = 0.29). At the conclusion of the breeding season, final pregnancy rates did not differ (P = ) between CONTROL and BST treatments. However, final pregnancy rates differed (P<0.001) among location, and ranged from 76.5 to 96.8%. Crown-to-rump length was measured on d 28 and did not differ (P = 0.54) between CONTROL and BST treatments (9.1 ± 0.3 vs. 9.3 ± 0.3 mm, respectively), however, there was an effect of location (P = 0.03). No treatment location interaction was detected (P = 0.43). Crown-to-nose length was recorded on d 60 and no differences (P = 0.89) were detected between CONTROL and BST treatments (27.2 ± 0.6 vs ± 0.6 mm, respectively). Acknowledgements The authors thank the Florida Cattle Enhancement Fund DACS for providing the research funding; Zoetis Animal Health (Parsippany, NJ) for their donation of PGF 2α (Lutalyse), GnRH (Factrel), and CIDR inserts (EAZI-BREED CIDR); as well as the Cherokee Ranch (Marianna, FL) and the Virginia Department of Corrections (Southhampton, VA) for providing heifers and labor for the implementation of the study. Literature Cited Bilby, T. R., et al J. Dairy Sci. 87: Cooke, R. F., et al J. Anim. Sci. 91: Gong, J. G., et al J Reprod Fertil. 110: Gong, J. G., et al J. Endocrinol. 97: Gong, J. G., et al Biol. Reprod. 949: Hartnell, G. F., et al J. Dairy Sci. 74: Kirby, C. J., et al J. Dairy Sci. 80: De La Sota, R. L., et al J. Dairy Sci. 76: Lucy, M. C J. Dairy Sci. 83: Mercadante, V. R. G., et al J. Anim. Sci. 94: Moreira, F., et al J. Dairy Sci. 84: Moreira, F., et al Theriogenology. 57: Ribeiro, E. S., et al Biol. Reprod. 90:1 12. Starbuck, M. J., et al Anim. Reprod. Sci. 93: Florida Beef Research Report

142 Table 1. Fertility and embryo/ fetal development in beef heifers treated with recombinant bovine somatotropin Treatment 1 BST Item CONTROL Estrus Response, % PR/AI 2, % Final PR 3, % Fetal size 4, mm CRL d CNL d Heifers assigned to the BST (n = 191) treatment received a 650-mg injection of bovine somatotropin (bst), an injection of gonadotropin-releasing hormone (GnRH), and a controlled internal drug release (CIDR; 1.38 g of progesterone) insert on d -9; an injection of prostaglandin F 2α (PGF 2α) at CIDR removal on d -2; and a second injection of GnRH concurrent with fixed-time AI (TAI) 54 ± 2 h later on d 0. CONTROL heifers (n = 223) were treated the same as BST, however, did not receive an injection of bst on d Pregnancy diagnosis was performed by ultrasonography between d 28 and 35 to determine pregnancy rates to AI (PR/AI). 3 Final pregnancy rates (PR). Pregnancy diagnosis was performed at least 30 d after the end of the breeding season. 4 CRL = crown-to-rump length; CNL = crown-to-nose length. Figure.1 Schematic of treatments. Heifers assigned to the BST (n = 191) treatment received a 650-mg injection of bovine somatotropin (bst), an injection of gonadotropin-releasing hormone (GnRH), and a controlled internal drug release (CIDR; 1.38 g of progesterone) insert on d -9; an injection of prostaglandin F 2α (PGF 2α) at CIDR removal on d -2; and a second injection of GnRH concurrent with fixed-time AI (TAI) 54 ± 2 h later on d 0. CONTROL heifers (n = 223) were treated the same as BST, however, did not receive an injection of bst on d -9. Blood samples (BS) were collected on d -9, 0, 28, and d 60. Follicle diameter (FD) was measured on d -2 and again on d 0. Pregnancy diagnosis was performed by ultrasonography between d 28 and 35 and again at least 30 d after the end of the breeding season. Crown-to-rump length (CRL) was measured on d 28, and crown-to-nose length (CNL) was measured on d Florida Beef Research Report

143 Concentration of IGF-1, ng/ml * Day relative to TAI CONTROL BST Figure 2. Plasma concentrations of insulin-like growth factor 1 (IGF-1) of beef heifers per d relative to fixed-time AI (TAI) by treatment. BST heifers received 650 mg of bovine somatotropin (bst) on d -9, whereas CONTROL heifers did not receive bst. * Effect of treatment (P<0.001); treatment day interaction (P<0.001) Florida Beef Research Report

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145 Comparison of Two Alternate PGF2α Products in Two Estrus Synchronization Protocols in Beef Heifers N. Oosthuizen 1, A. C. Lansford 2, L. B. Canal 1, P. L. P. Fontes 1, C. D. Sanford 1, C. R. Dahlen 3, N. DiLorenzo 1, R. N Funston 2, and G. C. Lamb 4 Synopsis Two experiments were conducted to evaluate the effects of a high concentrate, subcutaneous (s.c.) PGF 2α (Prostaglandin F 2α) compared with a conventionally concentrated, intramuscular (i.m.) PGF 2α in estrus synchronization protocols for heifers. No differences were detected in estrus response or pregnancy rates to artificial insemination (PR/AI) between treatments. Summary In experiment, 1, 869 Angus-based beef heifers were enrolled at 8 locations. All heifers were exposed to the 7-d CO-Synch + controlled internal drug release (CIDR) estrus synchronization protocol. On d -7 of the protocol heifers received 100 µg of gonadotropin-releasing hormone (GnRH) i.m., and a CIDR insert for 7 d. On d 0, at CIDR removal, estrus detection patches were applied to heifers and, within location, heifers randomly received 1 of 2 PGF 2α treatments: 5 ml of Lutalyse i.m. (CONTROL; n = 434) or a 2 ml of Lutalyse HighCon s.c. (HiCON; n = 435). A second GnRH injection was administered at 54 ± 2 h and heifers were fixed-time AI (TAI). Heifers were evaluated for estrus activity prior to TAI. Pregnancy rates to AI were diagnosed by transrectal ultrasonography between 35 and 55 d after TAI. The percentage of heifers exhibiting estrus between d 0 and TAI did not differ (P = 0.68) between CONTROL and HiCON treatments (47 vs. 46 ± 4%, respectively). Additionally, PR/AI were similar (P = 0.65) between CONTROL and HiCON treatments (46 vs. 45 ± 3%). In experiment 2, 190 Angus-based beef heifers were enrolled at 2 locations. Heifers were exposed to the melengestrol acetate (MGA) - PGF 2α protocol where they were offered 0.5 mg MGA/d from d 1 to 14. On d 33, heifers were randomly assigned to receive CONTROL (n = 95) or HiCON (n = 95) treatment, and estrus detection aids were applied. Heifers were exposed to AI 12 h after being detected in estrus. Heifers not detected in estrus at location 1 from d 33 to 39 received a second PGF 2α injection 6 d after the initial PGF 2α injection, and were exposed to natural service. Heifers at location 2 which did not express estrus from d 33 to 36 were administered 100 µg of GnRH i.m. and exposed to TAI 96 h post PGF 2α injection. Transrectal ultrasonography was used to diagnose PR/AI between 51 and 57 d after the initial PGF 2α injection. The percentage of heifers exhibiting estrus during the estrus detection period was similar (P = 0.40) between CONTROL and HiCON treatments (82 vs. 87 ± 4%). Furthermore, PR/AI were similar (P = 0.62) between CONTROL and HiCON treatments (60 vs. 65 ± 5%). We conclude that the 2 concentrations and corresponding routes of administration of PGF 2α were similar in efficacy at synchronizing estrus in beef heifers. Introduction The beef industry regularly incurs economic losses due to carcass lesions resulting from improper injection technique (Pratt, 2004). Intramuscular injections cause muscle trauma which results in an increase in connective tissue around the site during wound healing; therefore, this tissue damage negatively impacts beef tenderness (Boleman et al., 1998) and consumer acceptability of beef (Fajt et al., 2011). The Beef Quality Assurance program advises producers to use a s.c. route of administration when possible to improve tenderness. Subcutaneous administration may reduce the occurrence of blemishes on 1 North Florida Research and Education Center, University of Florida, Marianna, FL 2 West Central Research and Extension Center, University of Nebraska, North Platte, NE 3 Department of Animal Sciences, North Dakota State University, Fargo, ND 4 Department of Animal Science, Texas A&M University, College Station, TX Florida Beef Research Report

146 beef carcasses (Powell, 2013), improve tenderness (Griffin et al., 1998), and reduce the income lost per head at slaughter (Hilton, 2004). A high concentrate PGF 2α product, Lutalyse HighCon, was recently been approved for use by the United States Food and Drug Administration. According to label directions, Lutalyse HighCon may be administered by i.m. or s.c. injection in bovine females. To date, no research has been conducted to determine the effectiveness of this product in estrus synchronization protocols for beef heifers. Therefore, this study was performed to evaluate the efficacy of the high concentrate PGF 2α product, Lutalyse HighCon, by determining its effectiveness in estrus response and pregnancy rates in beef heifers. Materials and Methods Experiment 1 This study was conducted during the summer of Angus-based crossbred, yearling heifers (n = 869; 895 ± 4 lb BW) were enrolled at 8 locations in 2 states (South Dakota and North Dakota). All heifers were exposed to the 7-d CO-Synch + CIDR protocol. On d -7, heifers received a 2-mL i.m. injection of GnRH and a CIDR insert containing 1.38 g of progesterone. On d 0, at CIDR removal, estrus detection patches were applied, and heifers were randomly assigned to receive 1 of 2 PGF 2α treatments. Heifers assigned to the CONTROL treatment (n = 434) received a 5-mL i.m. injection of Lutalyse (5 mg of dinoprost tromethamine/ml), whereas those assigned to the HiCON treatment (n = 435) received a 2-mL s.c. injection of Lutalyse HighCon (12.5 mg of dinoprost tromethamine/ml). All heifers received a 100- μg injection of GnRH and were inseminated 54 ± 2 h after CIDR removal. Estrus detection patches were utilized for estrus detection between CIDR removal and TAI. Heifers were considered to be in estrus when at least 50% of the rub-off coating was removed from the patch, or when the patch was absent. No less than 10 d after TAI, heifers were exposed to bulls for the remainder of the breeding season at 6 locations. Transrectal ultrasonography was performed between d 35 and 55 after TAI to determine PR/AI. Final pregnancy rates were determined by transrectal ultrasonography at least 35 d after the end of the breeding season. Experiment 2 Yearling, Angus-based crossbred heifers (n = 190) were managed at 2 locations. Heifers at location 1 (n = 100; 750 ± 7 lb BW; L1) were managed at the West Central Research and Extension Center near North Platte, NE. Each heifer was offered a ration consisting of 14 lb grass hay, 8 lb wet corn gluten feed, and 1 lb of 1 of 2 mineral supplements. Heifers were synchronized using a melengestrol acetate (MGA) - PGF 2α protocol. Heifers were offered 0.5 mg of MGA pellets in their diet per d from d 1 to 14. On d 33, heifers were blocked by previous treatments and assigned to either CONTROL (n = 50) or HiCON (n = 50) treatment. An estrus detection patch was applied concurrently with the PGF 2α injection. All heifers were managed together and continuously observed for estrus from d 33 to 39. Heifers were considered to be expressing estrus when at least 50% of the rub-off coating was removed from the patch or when the patch was absent. Heifers were AI 12 h after estrus was detected. Heifers not detected in estrus between d 33 and 39 (n = 16) were given an injection of Lutalyse HighCon and placed with 2 bulls for natural service exposure. Heifers exposed to AI were placed in a separate pasture for 10 d before being placed with those not detected in estrus. Heifers remained with bulls for a 60 d breeding season at a ratio of 1:50. Pregnancy rates to AI and final pregnancy rates were diagnosed via transrectal ultrasonography (Aloka, Hitachi Aloka Medical America Inc., Wallingford, CT) 51 and 127 d after the initial PGF 2α injection, respectively. A second group of yearling, Angus-based crossbred heifers were managed at the Kelly Ranch near Sutherland, NE (n = 90; 719 ± 9 lb BW; location 2, L2), and were offered a ration containing 1.3 lb wet distillers grains, 5.3 lb grass hay, 7.1 lb corn silage, and 0.4 lb balancer pellets. Heifers were synchronized with the MGA-PGF 2α protocol as previously described for L1 and assigned randomly to receive CONTROL (n = 45) or HiCON (n = 45) treatment Florida Beef Research Report

147 Heifers were observed for estrus continuously from d 33 to 36. Heifers detected in estrus were AI approximately 12 h later. Heifers not expressing estrus by 96 h (n = 14) were administered 2 ml of GnRH, and TAI. Ten d following AI, 2 bulls were placed with heifers at a ratio of 1:45 during a 40 d breeding season. Pregnancy rates to AI were diagnosed via transrectal ultrasonography 57 d after the initial PGF 2α injection, and BW was concurrently recorded. A final pregnancy diagnosis was performed 50 d after the initial pregnancy diagnosis on heifers not diagnosed pregnant to AI, and BW was simultaneously recorded. All data was analyzed as a completely randomized design using the GLIMMIX procedure of SAS (SAS Institute, Inc., Cary, N.C) with heifer as the experimental unit. Results Experiment 1 Estrus expression between d 0 and TAI did not differ between CONTROL and HiCON treatments (P = 0.68); however, estrus expression differed among locations (P<0.01) and ranged from 36 to 65%. No treatment location interaction was detected (P = 0.37). Pregnancy rate to TAI did not differ between CONTROL and HiCON treatments (P = 0.65); however, there was an effect of location (P<0.01) on PR/AI, which ranged from 38 to 61%. No treatment location interaction was detected (P = 0.18). At the conclusion of the breeding season, final pregnancy rates did not differ between CONTROL and HiCON treatments (P = 0.95). Final pregnancy rates differed (P<0.01) among location, and ranged from 78 to 98%. Experiment 2 The percentage of heifers detected in estrus was similar between CONTROL and HiCON treatments at 60 h (P = 0.15), at 72 h (P = 0.51), and at 72 h (P = 0.27). There was a tendency (P<0.08) for a location effect at 60 h and 72 h. The total percentage of heifers observed in estrus throughout the detection period was also similar between treatment groups (P = 0.40). A treatment location interaction (P = 0.03) was detected for PR/AI between L1 (44 vs. 64 ± 7%, CONTROL vs. HiCON) and L2 (73 vs. 62 ± 7%, CONTROL vs. HiCON). Final pregnancy rates were similar between treatments (P = 0.11) and did not differ (P = 0.96) by location. Acknowledgements The authors thank Zoetis Animal Health (Parsippany, NJ) for their donation of PGF 2α (Lutalyse and Lutalyse HighCon). The authors also thank ABS Global (DeForest, WI) for their semen donation, and the ABS Global representatives, K. Porter, J. Knock, and M. Sandbulte for their assistance in conducting this experiment. Literature Cited Boleman et al J. Anim. Sci. 76: Fajt et al J. Anim. Sci. 89: doi: /jas Griffin et al Nebraska Extension Publication. Pub. No. G A. Univ. of Nebraska Lincoln. p 1 4. Hilton, W. M Purdue Extension Publication. Pub. No. VY-60-W. Purdue Univ. p Powell, J Univ. of Arkansas Division of Agriculture Research and Extension Publication. Pub. No. FSA3109. Univ. of Arkansas. p Pratt, J. H Injection damage. In: A. H. Andrews, editor, Bovine Medicine: Diseases and husbandry of cattle. Blackwell Publishing, Ames, IA. p Florida Beef Research Report

148 Table 1. Estrus response at the time of fixed-time artificial insemination in heifers after receiving conventional or high concentrate PGF 2α (Exp. 1) Treatment 1 Item CONTROL HiCON Overall SEM P-value n/n (%) Location SD-1 11/25 (44.0) 16/25 (64.0) 27/50 (54.0) wxy SD-2 15/29 (51.7) 17/27 (63.0) 32/56 (57.1) wx SD-3 33/70 (47.1) 30/70 (42.9) 63/140 (45.0) xyz SD-4 13/31 (41.9) 10/29 (34.5) 23/60 (38.3) yz SD-5 27/63 (42.9) 18/64 (28.1) 45/127 (35.4) z SD-6 25/40 (62.5) 29/43 (67.4) 54/83 (65.1) w SD-7 43/110 (39.1) 38/110 (34.6) 81/220 (36.8) z ND 35/65 (53.9) 41/67 (61.2) 76/132 (57.6) w Overall 202/433 (46.7) 199/435 (45.7) All heifers were estrus synchronized using the 7-d CO-Synch + controlled internal drug release (CIDR) protocol. Heifers were randomly assigned to receive 1 of 2 prostaglandin F2α (PGF2α) treatments at CIDR removal. Heifers assigned to the CONTROL treatment (n = 417) received a 5-mL i.m. injection of Lutalyse, whereas those assigned to the HiCON treatment (n = 424) received a 2-mL s.c. injection of Lutalyse HighCon. w - z Percentages within column for location differ (P 0.05). Table 2. Pregnancy rates to fixed-time artificial insemination in heifers after receiving conventional or high concentrate PGF 2α (Exp. 1) Treatment 1 Item CONTROL HiCON Overall SEM P-value n/n (%) Location SD-1 12/25 (48.0) 9/25 (36.0) 21/50 (42.0) yz SD-2 9/29 (31.0) 16/27 (59.3) 25/56 (44.6) xyz SD-3 34/70 (48.6) 29/70 (41.4) 63/140 (45.0) yz SD-4 22/31 (71.0) 15/29 (51.7) 37/60 (61.7) x SD-5 27/63 (42.9) 21/64 (32.8) 48/127 (37.8) z SD-6 19/40 (47.5) 25/43 (58.1) 44/83 (53.0) xy SD-7 44/110 (40.0) 40/110 (36.4) 84/220 (38.2) z ND 28/66 (42.4) 28/67 (41.8) 56/133 (42.1) yz Overall 195/434 (44.9) 183/435 (42.1) All heifers were estrus synchronized using the 7-d CO-Synch + controlled internal drug release protocol (CIDR). Heifers were randomly assigned to receive 1 of 2 prostaglandin F 2α (PGF 2α) treatments at CIDR removal. Heifers assigned to the CONTROL treatment (n = 417) received a 5-mL i.m. injection of Lutalyse, whereas those assigned to the HiCON treatment (n = 424) received a 2-mL s.c. injection of Lutalyse HighCon. Pregnancy rate to TAI was recorded between d 35 and 55 after TAI. x - z Percentages within column for location differ (P 0.05) Florida Beef Research Report

149 Table 3. Time of estrus for yearling beef heifers given 2 alternate PGF 2α injections (Exp. 2) Treatment 1 P- value 2 CONTROL HiCON SEM TRT Location T L Estrus response, % 60 h h h Total Response Heifers were administered 1 of 2 alternate prostaglandin F 2α (PGF 2α) products on d 33 as part of a melengestrol acetate (MGA) -PGF 2α protocol. CONTROL: 5 ml of Lutalyse (n = 5) i.m. or HiCON: 2 ml of Lutalyse HiCon n = 95) s.c. 2 TRT: PGF 2α injection treatment main effect; Location: location main effect; T L: PGF 2α injection treatment location interaction. Table 4. Pregnancy rates of yearling beef heifers given 1 of 2 alternate PGF 2α injections (Exp. 2) Treatment 1 P- value 2 CONTROL HiCON SEM TRT Location T L AI Pregnancy 3, % Overall Pregnancy 4, % Heifers were administered 1 of 2 alternate prostaglandin F 2α (PGF 2α) products on d 33 as part of a melengestrol acetate (MGA) -PGF 2α protocol. CONTROL: 5 ml of Lutalyse (n = 95) i.m. or HiCON: 2 ml of Lutalyse HighCon (n = 95) s.c. 2 TRT: P-value represents the main effects of treatment; Location: P-value represents main effects of location; T L: P-value represents the treatment location interaction. 3 Artificial insemination pregnancy was diagnosed via transrectal ultrasonography a minimum of 51 d after PGF 2α treatment. 4 Final pregnancy diagnosis was conducted via transrectal ultrasonography a minimum of 107 d after PGF 2α treatment Florida Beef Research Report

150 Florida Beef Research Report

151 Effects of Administration of Prostaglandin F2α 7 Days Prior to Initiation of the 7-Day COsynch + CIDR Protocol in Beef Heifers on Estrus Response and Pregnancy Rates N. Oosthuizen 1, L. B. Canal 1, P. L. P. Fontes 1, C. D. Sanford 1, N. DiLorenzo 1, C. R. Dahlen 2, G. E. Seidel 3 and G. C. Lamb 4 Synopsis This study was conducted to determine the effects of administration of 25 mg of PGF 2α (prostaglandin F 2α) 7 d prior to the initiation of the 7-d CO-Synch + controlled internal drug release (CIDR) fixed-time artificial insemination (TAI) protocol in beef heifers. The additional PGF 2α injection increased estrus response at the start of the protocol, and decreased estrus response prior to TAI. No differences were detected in pregnancy rates to AI (PR/AI) between treatments. Summary A total of 985 Bos taurus beef heifers were enrolled in a completely randomized design at 9 locations during the summer of Within location, all heifers were randomly assigned to 1 of 2 treatments: 1) CONTROL (n = 496); 100-µg injection of GnRH (gonadotropin-releasing hormone) and a CIDR insert for 7 d (d -7), administration of 25 mg of PGF 2α at CIDR removal (d 0), followed by a second injection of GnRH and TAI 54 ± 2 h later; or 2) PRESYNCH (n = 489); same as CONTROL but heifers received an additional injection of 25 mg of PGF 2α 7 d prior (d -14) to CIDR insertion. Estrus detection patches were applied to all heifers on d -14 and were evaluated for estrual activity on d -7. Similarly, estrus alert patches were placed on all heifers on d 0 and evaluated for estrual activity at the time of TAI. Pregnancy was diagnosed via transrectal ultrasonography between 35 and 55 d after TAI. The percentage of heifers exhibiting estrus between d -14 and d -7 was greater (P<0.001) for the PRESYNCH (70.1 ± 2.4%) than the CONTROL (41.1 ± 2.3%) treatment, whereas the percentage of heifers exhibiting estrus between d 0 and TAI was greater (P<0.001) for the CONTROL (55.6 ± 2.4%) than the PRESYNCH (39.7 ± 2.5%) treatment. Estrus response rates differed (P<0.001) among locations. Pregnancy rates to TAI differed P = 0.02) among locations; however, did not differ (P = 0.74) between CONTROL and PRESYNCH treatments (45.4 ± 2.5 vs ± 2.5%, respectively). Final breeding season pregnancy rates did not differ (P =.81) between treatments. Therefore, an injection of PGF 2α 7 d prior to initiation of the 7-d CO- Synch + CIDR protocol failed to improve pregnancy rates to TAI in replacement beef heifers. Introduction By controlling the bovine estrous cycle with exogenous hormones, TAI may be facilitated, and the time and labor associated with estrus detection may be reduced. Presynchronization involves the administration of preliminary hormones prior to the initiation of an estrus synchronization protocol. The utilization of GnRH or PGF 2α before the commencement of a TAI protocol may increase the proportion of dominant follicles that respond to the first GnRH injection, and may therefore improve the synchronization of the subsequent follicular growth waves (Kojima et al., 2000; Busch et al., 2007; Atkins et al., 2008). Presynchronization may also synchronize estrus more effectively, with resulting greater fertility (Patterson et al., 2003). This study was performed to evaluate the effects of an injection of PGF 2α 7 d prior to the initiation of the 7-d CO-Synch + CIDR protocol on fertility in replacement beef heifers. We hypothesized that an injection of PGF 2α 7 d before the initiation of the 7-d CO-Synch + CIDR protocol would improve PR/AI 1 North Florida Research and Education Center, University of Florida, Marianna, FL 2 Department of Animal Sciences, North Dakota State University, Fargo, ND 3 Animal Reproduction and Biotechnology Laboratory, Colorado State University, Fort Collins, CO 4 Department of Animal Science, Texas A&M University, College Station, TX Florida Beef Research Report

152 by increasing the estrus response between d -14 and d -7, thereby increasing the proportion of heifers that respond to the PGF 2α injection on d 0. Materials and Methods A total of 985 Bos taurus beef heifers were enrolled across 9 locations in 3 states (South Dakota, North Dakota, and Colorado). Within location, heifers were randomly assigned to 1 of 2 treatments: 1) estrus detection patches were applied on d -14, 100 μg of GnRH was administered at CIDR (1.38 g progesterone) insertion on d -7, 25 mg of PGF 2α was administered at CIDR removal concurrently with a second estrus detection patch application on d 0, followed 54 ± 2 h later by the administration of 100 μg of GnRH and TAI (CONTROL; n = 496); or 2) heifers were treated the same as the CONTROL treatment with the addition of a 25 mg injection of PGF 2α 7 d prior to CIDR insertion on d -14 (PRESYNCH; n = 489). Estrus detection patches were examined for activation on d -7 (EST1) and at the time of TAI (EST2). Estrus detection patches were considered activated when at least 50% of the rub-off coating was removed, or when the patch was absent. No less than 10 d after TAI, heifers were exposed to bulls for the remainder of the breeding season at 7 locations. Transrectal ultrasonography was performed between d 35 and 55 after TAI to determine the presence of a viable embryo, thereby assessing PR/AI. Final overall pregnancy rates were determined by transrectal ultrasonography at least 35 d after the end of the breeding season. All data was analyzed as a completely randomized design using the GLIMMIX procedure of SAS (SAS Institute, Inc., Cary, N.C.) with heifer as the experimental unit. Results Between estrus patch application on d -14 and patch examination on d -7, estrus expression differed (P<0.001) between treatments. Estrus expression was greater in PRESYNCH compared with CONTROL treatments, and differed among locations (P<0.001). The percentage of heifers exhibiting estrus behavior between d-14 and d-7 ranged from 47.3 to 79.7% among locations; however, no treatment location interaction was detected (P = 0.57). Although heifers in the PRESYNCH treatment had a lower estrus response between d 0 and TAI compared with those in the CONTROL treatment, PR/AI did not differ (P = 0.74). In contrast, there was an effect of location (P = 0.02) on PR/AI, which ranged from 37.8 to 61.7%. No treatment location interaction was detected (P = 0.69). At the conclusion of the breeding season, final pregnancy rates did not differ (P = 0.81) between CONTROL and PRESYNCH treatments respectively. Final pregnancy rates differed (P<0.001) among location, and ranged from 78.3 to 97.9%. Acknowledgements The authors thank Zoetis Animal Health (Parsippany, NJ) for their donation of PGF 2α (Lutalyse). The authors also thank ABS Global (DeForest, WI) for their semen donation, and K. Porter, J. Knock, and M. Sandbulte for their assistance in conducting this experiment. Literature Cited Atkins et al J. Anim. Sci. 86: Busch et al J. Anim. Sci. 85: Kojima et al J. Anim. Sci. 78: Patterson et al J. Anim. Sci. 81:E166 E Florida Beef Research Report

153 Table 1. Estrus response on d -7 in replacement beef heifers that either received or did not receive an injection of PGF 2α 7 d before initiation of estrus synchronization Treatment 1 Item CONTROL PRESYNCH Overall SEM 2 P-value n/n (%) Location SD-1 9/25 (36.0) 17/25 (68.0) 26/50 (52.0) yz SD-2 9/28 (32.1) 19/28 (67.9) 28/56 (50.0) yz SD-3 29/70 (41.4) 44/70 (62.9) 73/140 (52.1) yz SD-4 12/32 (37.5) 18/28 (64.3) 30/60 (50.0) yz SD-5 20/64 (31.3) 47/63 (74.6) 67/127 (52.8) yz 8.3 < SD-6 14/41 (34.2) 28/42 (66.6) 42/83 (50.6) yz SD-7 40/111 (35.9) 64/109 (58.6) 104/220 (47.3) z 6.4 < ND 46/67 (68.7) 60/66 (90.9) 106/133 (79.7) x CO 25/58 (43.1) 46/58 (79.3) 71/116 (61.2) y 8.7 < Overall 4 204/496 (41.1) 343/489 (70.1) 3.3 < CONTROL: heifers received a 100-μg injection of gonadotropin-releasing hormone (GnRH) at controlled internal drug release (CIDR; 1.38 g progesterone) insertion [d -7], a 25-mg injection of prostaglandin F 2α (PGF 2α) administered at CIDR removal [d 0], and an injection of GnRH and fixed-time artificial insemination (TAI) 54 ± 2 h later (n = 496). PRESYNCH: treated the same as CONTROL, but received an additional 25-mg injection of PGF 2α 7 d prior to the first GnRH injection on d -14 (n = 489). Estrus detection patches were applied to all heifers on d -14 and were examined for activation on d SEM: Standard error of the mean between CONTROL and PRESYNCH treatments within row. 3 P-value represents the difference between CONTROL and PRESYNCH treatments within row. 4 Overall estrus response on d -7 differed (P<0.001) between treatments. x,y,z Percentages within column with different superscripts differ (P 0.05) Florida Beef Research Report

154 Table 2. Estrus response at the time of TAI in replacement beef heifers that either received or did not receive an injection of PGF 2α 7 d before initiation of estrus synchronization Treatment 1 Item CONTROL PRESYNCH Overall SEM 2 P-value n/n (%) Location SD-1 15/25 (60.0) 12/25 (48.0) 27/50 (54.0) wxy SD-2 19/28 (67.9) 13/28 (46.4) 32/56 (57.1) wx SD-3 40/70 (57.1) 23/70 (32.9) 63/140 (45.0) xyz SD-4 16/32 (50.0) 7/28 (25.0) 23/60 (38.3) yz SD-5 31/64 (48.4) 14/63 (22.2) 45/127 (35.4) z SD-6 26/41 (63.4) 28/42 (66.7) 54/83 (65.1) w SD-7 45/111 (40.5) 36/109 (33.0) 81/220 (36.8) z ND 44/66 (66.7) 32/66 (48.5) 76/132 (57.6) w CO 39/58 (67.2) 29/58 (50.0) 68/116 (58.6) w Overall 4 275/495 (55.6) 194/489 (39.7) 3.4 < CONTROL: heifers received a 100-μg injection of gonadotropin-releasing hormone (GnRH) at controlled internal drug release (CIDR; 1.38 g progesterone) insertion [d -7], a 25-mg injection of prostaglandin F 2α (PGF 2α) administered at CIDR removal [d 0], and an injection of GnRH and fixed-time artificial insemination (TAI) 54 ± 2 h later (n = 4 95). PRESYNCH: treated the same as CONTROL, but received an additional 25-mg injection of PGF 2α 7 d prior to the first GnRH injection on d -14 (n = 489). Estrus detection patches were applied on d 0 and were examined for activation at the time of TAI. 2 SEM: Standard error of the mean between CONTROL and PRESYNCH treatments within row. 3 P-value represents the difference between CONTROL and PRESYNCH treatments within row. 4 Overall estrus response at the time of TAI differed (P<0.001) between treatments. w,x,y,z Percentages within column with different superscripts differ (P 0.05) Florida Beef Research Report

155 Table 3. Pregnancy rates to TAI in replacement beef heifers that either received or did not receive an injection of PGF 2α 7 d before initiation of estrus synchronization Treatment 1 Item CONTROL PRESYNCH Overall SEM 2 P-value n/n (%) Location SD-1 13/25 (52.0) 8/25 (32.0) 21/50 (42.0) yz SD-2 12/28 (42.9) 13/28 (46.4) 25/56 (44.6) xyz SD-3 34/70 (48.6) 29/70 (41.4) 63/140 (45.0) xyz SD-4 17/32 (53.1) 20/28 (71.4) 37/60 (61.7) x SD-5 24/64 (37.5) 24/63 (38.1) 48/127 (37.8) z SD-6 21/41 (51.2) 23/42 (54.8) 44/83 (53.0) xy SD-7 46/111 (41.4) 38/109 (34.9) 84/220 (38.2) z ND 28/67 (41.8) 28/66 (42.4) 56/133 (42.1) yz CO 30/58 (51.7) 28/58 (48.3) 58/116 (50.0) xyz Overall 225/496 (45.4) 211/489 (43.2) CONTROL: heifers received a 100-μg injection of gonadotropin-releasing hormone (GnRH) at controlled internal drug release (CIDR; 1.38 g progesterone) insertion [d -7], a 25-mg injection of prostaglandin F 2α (PGF 2α) administered at CIDR removal [d 0], and an injection of GnRH and fixed-time artificial insemination (TAI) 54 ± 2 h later (n = 496). PRESYNCH: treated the same as CONTROL, but received an additional 25-mg injection of PGF 2α 7 d prior to the first GnRH injection on d -14 (n = 489). Pregnancy diagnosis was performed by ultrasonography between d 35 and 55 after TAI. 2 SEM: Standard error of the mean between CONTROL and PRESYNCH treatments within row. 3 P-value represents the difference between CONTROL and PRESYNCH treatments within row. x,y,z Percentages within column with different superscripts differ (P 0.05) Florida Beef Research Report

156 Florida Beef Research Report

157 Bahiagrass Performance Under Low Soil Nitrogen J. Dubeux 1, E. R. S. Santos, L. Garcia-Jimenez, D. Jaramillo, A. Blount, and C. Mackowiak Synopsis In Florida, bahiagrass (Paspalum notatum Flügge) is mostly used for hay and grazing and it is known for its persistance under low input systems. However, improved varieties may present different reponses. This study aimed to compare the performance if six different bahiagrass cultivars under low N input management. Summary Bahiagrass is the most common forage species in FL. Nitrogen fertilization is a available tool that not always can be used due to its cost. Improved cultivars of bahiagrass can potentialy respond diffenrently under low N input managemente. The goal of this study was to compare the performance of six bahiagrass cultivars under low N input. Five harvests were made in 2014 and 2015 to estimate the herbage accumulation and crude protein. Roots and rhizomes were sampled at the end of each season, in order to obtain the belowground biomass. Under low N input, better varieties do not express their productive potential; therefore, under these conditions, no significant gain is expected planting improved varieties of bahiagrass. In comparison, greater soil N fertility should result in the newer bahiagrass varieties outperforming older varieties. Development of new bahiagrass varieties under low soil N is necessary to improve yields under such conditions. Introduction Bahiagrass is the most common and widely used warm-season perennial grass in Florida. It covers over 2 million acres in Florida and over 4 million acres in the Southeastern United States (Newman et al., 2014). Florida soils, in general, are sandy, with low soil organic matter (SOM) and nitrogen (N) fertility. As a result, fertilizer applications are necessary to achieve satisfactory production. Bahiagrass responds positively to N fertilizer applications in low N soils. However, livestock producers are not always able to apply optimal amounts of N to their pastures. Some grasses are more adapted to low input systems than others. Bahiagrass, in general, is more adapted to low soil fertility compared to other grasses, such as bermudagrass hybrids (e.g. Tifton 85); however, not all bahiagrass varieties respond to the same degree. In most cases, these varieties were selected under high-n input systems. It is important to determine how these varieties perform under low soil N, including above- and below-ground biomass responses. Materials and Methods At North Florida Research and Education Center, Marianna, we conducted a two-year trial to assess the performance of 6 bahiagrass cultivars without N fertilizer inputs. The studied cultivars were Argentine, Pensacola, UF Riata, Sand Mountain, Tifton 9, and TifQuik. These plots were previously established (June 20, 2005). The Coastal Plain soil was an Ultisol (Fuquay series). Initial (2014) soil composition (0-15 cm depth) were as follows: soil ph = 5.9, P = 19 ppm, K = 52 ppm, Mg = 59 ppm, Ca = 212 ppm, S = 33 ppm, B = 0.3 ppm, Zn = 1.5 ppm, Mn = 152 ppm, Fe = 20 ppm, Cu = 0.6 ppm, SOM = 0.7%, CEC = 2.9 meq/100 g. Plots were harvested every 5 weeks at 2 inch stubble height, each growing season (2014 and 2015). Five harvests were conducted each season. Following each harvest, we applied P, K, Ca, S, Mg, and micronutrients to ensure that N was the only limiting nutrient. Results Bahiagrass varieties produced differently according to harvest date. Varietal differences were most pronounced from May through July of the second year. Argentine bahiagrass resulted in lower DM yield (P<0.05) than Sand Mountain, Tifton 9, and TifQuik, but similar to UF Riata and Pensacola bahiagrass, at the June/July harvest (Figure 1). Above-ground yields declined 50% from year 1 to year 2, reflecting the importance of N fertilization on bahiagrass forage yield (Figure 2). Average yield per 5-week harvest was 636 lb DM/ac in 2014 and 310 lb DM/ac in Herbage crude protein (CP) concentration was similar Florida Beef Research Report

158 among bahiagrass varieties, ranging from 6.9 to 7.5% (Figure 4). In the first year, N mobilization from roots and rhizomes likely supported above-ground growth. It is important to mention; however, that after two years without adding N fertilizer, the plots were still maintaining the soil cover without weed encroachment. It seems that bahiagrass is able to buffer the absence of N fertilization by remobilizing N reserves from the root and rhizome pool. It is interesting to note the below-ground responses. In general, bahiagrass varieties doubled their root/rhizome biomass in the second year, compared to the first year (Figure 2 and 3). Reallocating biomass production from above-ground growth to roots and rhizomes, improves bahiagrass ability to further explore the soil and increase nutrient uptake through greater root exploration. References: Newman, Y., J. Vendramini, and A. Blount Bahiagrass (Paspalum notatum): overview and management. EDIS SS-AGR-332 available online at Herbage dry matter yield (lbs/acre) May/June June/Jul Jul/Aug Aug/Sept Sept/Oct Argentine Pensacola UF Riata Sand Mountain Tifton 9 TifQuik Figure 1. Herbage yield of bahiagrass varieties under low soil N. Data are averaged across two years (2014 and 2015). *Harvests occurred in 5/23/2014, 7/2/2014, 8/6/2014, 9/10/2014, 10/15/2014, 5/11/2015, 6/15/2015, 7/19/2015, 8/23/2015, 9/28/ Florida Beef Research Report

159 lbs DM/A Shoot biomass Root + rhizome biomass Figure 2. Shoot and root/rhizome biomass of bahiagrass varieties under low soil N; shoot biomass represents the sum of five harvests, averaged across varieties. Root and rhizome biomass represents onetime sampling at the end of the season (October) of each year Florida Beef Research Report

160 Root and rhizome biomass (lb/a; 0-8 inches) Argentine Pensacola UF Riata Sand Mountain Tifton 9 TifQuik Figure 3. Root and rhizome biomass (0-8 inch soil depth) of bahiagrass varieties under low soil N. Crude Protein, % TifQuik Tifton 9 Sand Mountain UF Riata Pensacola Argentine Figure 4. Crude protein concentration of bahiagrass varieties under low soil N, data from No significant differences observed among bahiagrass varieties (P>0.05) Florida Beef Research Report

161 Annual and Perennial Peanut Mixed with Pensacola Bahiagrass in North Florida D.M. Jaramillo 1, J.C.B. Dubeux, Jr. 1, E.R.S. Santos 1, L. Garcia, L. 1 Synopsis Incorporating legumes into bahiagrass pastures can provide a range of benefits. Peanut species (Arachis spp.) have been studied as potential legumes, with rhizoma peanut being the most studied species. Seeded peanut species, A. hypagaea and A. pintoi, can be potential warm-season legumes that have been minimally studied in Florida. Ecoturf rhizoma peanut is the best species to plant into existing bahiagrass pastures, however common peanut (A. hypogaea) is viable to plant annually or bi-annually into bahiagrass pastures. Introduction Incorporating legumes into pastures is an option that producers can opt for in order to decrease the reliance on N fertilizers. Plenty of options are available when it comes to cool-season legumes, but there are less options when it comes to warm-season perennial legumes. In South Florida, some producers have tried implementing aeschynomene (Aeschynomene Americana L.) and carpon desmodium [Desmodium heterocarpon (L.) D.C.] into their pastures, but have been faced with challenges related to establishment and persistence of these legumes, thus adoption rates of these legumes has been minimal. Peanut (Arachis spp.) species may provide options for producers when it comes to warm-season perennial legumes. Rhizoma peanut is among the most predominant warm-season legumes in Florida. In hay systems, rhizoma peanut (Arachis glabrata Benth) has been successfully adopted by some producers, however in grazing systems the adoption rates have been lower largely due to its vegetative propagation, in which it can potentially take up to two growing seasons to develop an established stand. Upon establishment, rhizoma peanut is capable of persisting and providing high quality diets for beef cattle, having high crude protein levels (14-18%) and digestibility (62-67%) (Quesenberry et al. 2010). Williams et al. (1991) showed that steers grazing pastures in mixture with rhizoma peanut and bahiagrass had greater average daily gain than steers grazing bahiagrass alone (1.7 vs. 1.1 lbs.). Other, less-explored, legume options include seeded peanuts. Arachis hypogaea, or the common peanut, has been minimally evaluated for its forage potential. The University of Florida has an extensive peanut breeding program that has developed cultivars adapted to the Florida environment. Myer et al. (2010) evaluated A. hypogaea for its grazing potential, and reported declining herbage accumulation across a two-year grazing period, but the crude protein (16%) and digestibility (65%) of these species tends to be comparable to rhizoma peanut. Arachis pintoi is yet another possible seeded peanut that can be potentially incorporated into Florida pastures. Pintoi peanut is a stoloniferous, perennial species that is seed propagated that is ost commonly found in tropical regions of the world. It has been shown to be grazing tolerant and having high nutritive value (18% crude protein, and 70% digestibility). There is potential for developing mixed grass-legume systems in Florida using Arachis species in combination with bahiagrass. The goals of this study were to assess the viability of the common peanut (A. hypogaea) for its forage use, to assess the performance of pintoi and rhizoma peanut during the establishment period when mixed with bahiagrass, and to make recommendations on which peanut species is best suited for incorporation into existing bahiagrass pastures 1 North Florida Research and Education Center, University of Florida, Marianna, FL Florida Beef Research Report

162 Materials and Methods Experimental sites The study was conducted during the 2014, 2015, and 2016 growing seasons at the University of Florida - North Florida Research and Education Center (NFREC), in Marianna, FL (30 52 N, W, 35 m altitude). The soil at the experimental site is an Orangeburg loamy sand (fine-loamy- kaolinitic, thermic Typic Kandiudults). Initial composite soil samples (0-15 cm) were collected in May 2014 and results indicated a soil ph of 6.4 and Mehlich-1 extractable P, K, Mg, and Ca concentrations of 22, 67, 80, and 370 mg kg-1, respectively. Soil organic matter (SOM) was 8.6 g kg-1, and CEC was 3.5 meq 100g-1. Total rainfall for 2014, 2015, and 2016 was 1,573, 1,403, and 1,378 mm, respectively (Figure 1), compared to a long-term average of 1,361 mm. Treatments, planting, and design The plots were allocated on a well-established (10+ yr) Pensacola bahiagrass pasture, with each plot measuring 20x20 ft. Experimental design was a randomized complete block design with four replications per treatment. The treatments consisted of Pensacola bahiagrass in monoculture receiving no N fertilizer, and four legumes in mixture with bahiagrass. Legumes were one rhizoma peanut cultivar ( Florigraze ) and one germplasm (Ecoturf), TUFRunner 727 common peanut, and Amarillo pintoi peanut. All of the plots were planted on April 2014 and evaluated until October 2016 (Table 1). The rhizoma peanut entries were planted at 80 bushels per acre, using a Bermudagrass sprigger. The seeded peanuts were planted using a peanut planter with rows 2 ft. apart, with 8 rows per plot, resulting in seeding rates for annual and pintoi peanut of 110 and 11 lbs/acre, respectively. Harvesting The plots were harvested every 5 weeks at 4 inch stubble heights, starting in August in 2014, and May in 2015 and They were harvested by cutting a 3x10 ft2 strip using a flail mower at 4 inch stubble height. After harvesting, all of the plots were cut down so they were uniform for the next harvest. They were cut using a silage chopper, at 4inch stubble height. They were fertilized with 200 lbs./acre of after every harvest. Statistics Data were analyzed using proc mixed from SAS. Fixed effects included variety, year, and harvest date. Random effects included blocks and its interactions with fixed effects. Means were compared using the PDIFF procedure adjusted by Tukey (5%). Results and Discussion The herbage accumulation (Table 2) did not differ among the treatments in the first two years, but by the third year of the experiment (2016), the bahiagrass-ecoturf mixtures had 54% greater herbage accumulation than unfertilized bahiagrass (Table 1). The remaining mixtures were intermediate in herbage accumulation and were not different than bahiagrass-ecoturf mixtures or unfertilized bahiagrass. By 2016, both rhizoma peanut mixtures (Ecoturf and Florigraze) increased in their herbage accumulation, indicating these species were successfully established and becoming productive. In mixtures, both rhizoma peanut mixtures showed increasing proportions within their corresponding mixtures. Ecoturf had the largest presence by 2016, in which it consisted of 30% Ecoturf in their mixtures. The common peanut did re-seed naturally, however, the re-seeding was minimal and the stand was not able to reach the same population size from the previous year. This indicates that common peanut can act as an annual or bi-annual legume within bahiagrass pastures. Digestibility and crude protein was analyzed by component within the mixtures (grass or peanut). The digestibility of the grass components was improved when the grass was grown in mixture with peanuts when compared to bahiagrass growing in monoculture (51% vs. 48%). This occurs because the legumes can transfer the fixed nitrogen to the grasses growing in the mixtures, thus indicating one of the main Florida Beef Research Report

163 benefits from growing grass-legume mixtures. In addition, crude protein levels were above 13% for most of the evaluations, which further indicates the high nutritive value for these species (Figure 2). Conclusions and implications All peanut treatments in this study differed in their response levels. Rhizoma peanut cultivars, as expected because of slow establishment, became increasingly productive over the three-year period of the study, of which Ecoturf outperformed Florigraze when mixed with bahiagrass. Pintoi peanut was under represented in its responses due to its low-growth habit, which meant a high amount of its herbage mass was below the clipping height. Common peanut can serve as a reseeding annual legume in bahiagrass, but will likely need replanting every 2 yr. It had the greatest crude protein levels among treatments, and high digestibility. With access to planting equipment, and low seed costs, common peanut can be an alternative warm-season legume for incorporating into bahiagrass pastures. Overall, this study indicated Arachis spp. are viable legumes for incorporation into bahiagrass pastures in Florida, and their incorporation may lead to increased productivity of pasture systems compared with unfertilized bahiagrass. Literature Cited SAS Institute SAS statistics user s guide. Release version 6. SAS Inst., Cary, NC. Quesenberry, K.H., et al J. Plant Regist. 4: Williams, M.J., et al. Prod. Agric 4(1): Figure 1. Bahiagrass growing in mixture with common peanut in NFREC-Marianna. Photo credit: David M. Jaramillo, UF/IFAS NFREC Florida Beef Research Report

164 Table 1. Harvest dates for three growing seasons. Year August 11 May 4 May 16 September 17 June 9 June 21 October 28 July 15 July 3 September 17 August 6 October 22 September Table 2. Herbage accumulation totals by year for peanut-bahiagrass (BG) mixtures and unfertilized bahiagrass. Year Treatment lb DM ac Ecoturf-BG 1433 aa 1812 aa 3313 ab Florigraze-BG 1277 aa 1768 aab 2382 bb Amarillo-BG 1366 aa 2170 aab 2679 ab TUFRunner 727-BG 1493 aa 1498 aa 2679 abb Unfertilized BG 1518 aa 1723 aa 2158 ba SE Least squares means followed by the same letter, lowercase letters within a column and uppercase letters within a row, do not differ (P>0.05) according to PDIFF procedure adjusted by Tukey Peanut %CP Aug Oct June July Oct May June July Aug Sept Ecoturf-BG Florigraze-BG Amarillo- BG TUFRunner '727'-BG Figure 2. Peanut herbage crude protein (CP) percentage when mixed with bahiagrass (BG) Florida Beef Research Report

165 Warm-Season Grass-Legume Mixtures Options for North Florida E. Santos 1, J. Dubeux 1, C. Mackowiak 1, A. Blount 1, D. Jaramillo 1, L. Garcia 1, J. Shirley 1, B. Conrad 1, M. Ruiz-Moreno 1 Synopsis Nitrogen fertilization has a great impact on grass yield, however, N application may be costly for producers and may cause environmental damages. Legumes are capable of fixing atmospheric N. When grasses are growing in mixtures with legumes they can utilize this N, thus we aimed to investigate options for grass-legume mixtures during the warm-season for north Florida. Summary Mixing grasses and legumes may decrease the costs with N fertilization and create a more sustainable system. Two trials were performed on two farms to evaluate grass-legume options for north Florida. The first trial contained bahiagrass and the second trial contained bermudagrass. The treatments for each trial were unfertilized grass, N-fertilized grass, grass-alfalfa, grass-rhizoma peanut, alfalfa, and rhizoma peanut (RP), with the mixtures receiving half of the N applied in the N-fertilized grass. Each treatment was replicated four times in a completely randomized design. A total of seven harvests were made during the growing season to estimate herbage accumulation and botanical composition. In general, mixtures and N-fertilized grass presented similar herbage accumulation, however, legumes did not show a significant contribution throughout the year. Rhizoma peanut was not significant in the botanical composition, the stubble height used may have misrepresented RP contribution. Alfalfa had a greater contribution in the first harvest, and declined along the year, behaving as annual. Grass-legume mixtures may decrease N fertilization, nevertheless it is not clear if the similar herbage accumulation was caused due to the grasses could not respond to greater amounts of N fertilization than they were receiving in the mixtures. Introduction Hay production is one of the most important agricultural activities in North Florida. Bahiagrass, bermudagrass, and perennial peanut are the most planted forages in this area during the warm-season, and alfalfa has been considered an emerging crop in the region. Warm-season perennial grasses usually have high yields when properly managed and fertilized with nitrogen. However, nitrogen losses and market price variability may decrease farmers profitability. In addition, the manufacturing process, transportation, storage, and application of nitrogen add greenhouse gases to the atmosphere, which contribute to global warming. Nitrates can be leached and contaminate the groundwater. High levels of nitrate in drinking water may cause health problems in humans and animals. Forage legumes are capable of naturally fixing atmospheric nitrogen in association with rhizobia bacteria. Once growing together with legumes, grasses can utilize the fixed nitrogen and also stimulate the fixation due to nutrient competition. Mixing grasses and legumes can potentially decrease synthetic nitrogen fertilizer application, decrease production cost, mitigate environmental damages, and create a more sustainable system. This study aims to investigate the performance of grass-legume mixtures as an alternative to reduce industrial N fertilizer application. Material and Methods Two trials were designed to show the contrast between grass-legume mixture and their monocultures, they were replicated on two farms (Farm 1 and Farm 2). One trial contained bermudagrass cv. Tifton 85, as the grass component, while the other trial contained bahiagrass cv. Tifquik. For each trial, treatments are as follows: grass monoculture; grass monoculture + 80 lbs N/ac (after each harvest); perennial peanut (RP) monoculture (Florigraze), alfalfa monoculture (Alfagraze 600 RR), grass + RP + 40 lbs N/ac, and grass + alfalfa + 40 lbs N/ac. All treatments received 300 lbs of after each harvest. Each treatment Florida Beef Research Report

166 was replicated four times in a randomized complete block design. Plots measure 200 ft 2 (10 x 20 ft.) with alleys of 6 ft. between blocks and trials. Irrigation was applied at Farm 2 according to farmer s management. Measurements were taken every 5 wks during the growing season in an area of 5 ft 2 at 3 in. Grass and legume components were hand-separated and dried at 55 C for 72 h in order to obtain the yield and botanical composition. A series of herbicides were used to control weeds (Table 1.). Results Farm 1 Bahiagrass-legume mixtures Herbage accumulation (HA) Results showed that when bahiagrass was growing together with alfalfa or RP and receiving 40 lb N/ac the yield was similar to the N-fertilized bahiagrass (Figure 1A). May, June and August were the months with greater HA. Unfertilized bahiagrass HA was greater or similar than alfalfa and RP monocultures throughout most sampling dates, however, legume monocultures and unfertilized bahiagrass were never greater than any treatment receiving N fertilization. Rhizoma peanut and alfalfa were the least productive forage crops, followed by unfertilized bahiagrass. N-fertilized bahiagrass, bahiagrass-rp, and bahiagrassalfalfa total HA did not differ between each other during sampling dates. Botanical Composition (BC) The botanical composition was estimated in the mixed treatments, in order to assess the proportion of each component (grass or legume) in the stand. Rhizoma peanut did not have a representative contribution in the botanical composition. One factor that contributed to the non-appearance of RP in the BC was the stubble height used to harvest (7.5 cm) which was probably too high for RP. The mixture of alfalfabahiagrass had a significant proportion of alfalfa in the first harvest (61%), however in decline in the second (8%) and in the third evaluation (0.2%), disappearing completely in the fourth (Figure 2A). Farm 1 Bermudagrass-legume mixtures Herbage accumulation (HA) There was no difference among treatments in HA during the first two harvests. Most of the crops were dormant, only alfalfa was growing, however, it did not yield as much as expected. May was the best month for the DM production. The N-fertilized bermudagrass HA was 4068 lb DM/ac, and it was greater than any other treatment (Figure 1C). Mixtures were intermediate between N-fertilized bermudagrass and the other monocultures, besides all treatment differ among each other in May unfertilized bermudagrass and legumes were similar during most of the evaluations. However, the similarity in the first two months was due to physiological reasons, where bermudagrass and RP were still dormant.). Despite showing greater yield than all the monocultures, N-fertilized bermudagrass yield was only greater than both mixtures in May and September. Botanical Composition (BC) Rhizoma peanut presence above 7.5 inches was not significant in mixed stands. On the other hand, alfalfa was present in the mixtures, mainly during the first harvests of the year. Therefore, a decline from the first to the last harvest was noticed on both sites. Alfalfa contribution was 50% in April, however, it only represented 10, 5, and 1% in May, June, and August, respectively (Figure 2C). During September and October, there was no alfalfa left in the mixed plots. Farm 2 Bahiagrass-legume mixtures Herbage accumulation (HA) Mixtures of bahiagrass with RP or alfalfa had similar yield when compared to the N-fertilized bahiagrass and they were greater than unfertilized bahiagrass, alfalfa, and RP yield (Figure 1B). However, no difference was noticed in the first and second harvests (March and April) due to environmental conditions which did not favor warm-season legumes growth. May, June, and August were the months with greater forage mass. Unfertilized bahiagrass, RP, and alfalfa were the least productive treatments and did not differ between each other. It is important to mention that overall yield in Farm 2 was greater than in Florida Beef Research Report

167 Farm 1. This yield difference was caused by the irrigation used in Farm 2, while Farm 1 relied on rainfall only. Botanical composition (BC) As it happened in the non-irrigated site (Farm1), RP also did not have a representative contribution in the botanical composition. However, alfalfa had an average of 18% in the BC of the mixture of alfalfabahiagrass (Figure 2B), therefore the first and second harvests were the ones to have a greater proportion of alfalfa (34 and 40%, respectively). The contribution of alfalfa in the harvests occurring from May to October ranged from 5 to 17%. Farm 2. Bermudagrass-legume mixtures Herbage Accumulation (HA) The greater difference between treatments was in May when the N-fertilized bermudagrass out yielded all the other treatments (3230 lb DM/ac), followed by bermudagrass-rp and bermudagrass-alfalfa, which yielded 1722 and 1561 lb DM/ac, respectively (Figure 1D). Unfertilized bermudagrass, alfalfa, and RP were less productive than the other treatments. Botanical Composition (BC) When irrigation was present, alfalfa contribution was 84, 41, 19, 13, 4, and 2%, for April, May, June, August, September, and October (Figure 2D). Despite the better performance under irrigation, at the end of the season, the alfalfa presence in the mixed stands was not significant. Acknowledgements The authors acknowledge the Florida Department of Agriculture & Consumer Services for supporting the study. Table 1. Herbicides applied for controlling weeds. Treatments Strategy Product rate per acre Only Grass GrazonNext HL 1.5 pt Fertilized Grass GrazonNext HL 1.5 pt Grass + Peanut 2, 4 D 1 pt Grass + Alfalfa 2,4 DB pt Alfalfa (RR) Roundup 33 fl. oz Roundup wheathermax 4.5S Perennial Peanut Impose and Clethodim 4 oz and 12 oz, respectively Florida Beef Research Report

168 Figure 1. Grass-legume mixtures herbage accumulation in comparison with their monocultures. The N-fertilized grass received 80 lb N/ac/harvest, and the mixtures receive 40 lb N/ac/harvest. A) mixtures with bahiagrass at Farm 1; B) mixtures with bahiagrass at Farm 2; C) mixtures with bermudagrass at Farm 1; D) mixtures with bermudagrass at Farm Florida Beef Research Report

169 Figure 2. Grass-alfalfa mixtures botanical composition. A) mixture with bahiagrass at the Farm 1; B) mixture with bahiagrass at Farm 2; C) mixture with bermudagrass at Farm 1; D) mixture with bermudagrass at Farm Florida Beef Research Report

170 Florida Beef Research Report

171 Bermudagrass Varieties Testing in North Florida J. Dubeux 1, J. Vendramini 2, E. Rios 3, A. Blount 1, E. Santos 1, D. Jaramillo 1, L. Garcia 1 Synopsis A replicated core collection of bermudagrass with more than 250 entries was tested in Marianna, FL, with the objective of identifying new cultivars with potential to perform in livestock-forage systems in North Florida. Summary This project is part of a statewide effort to develop new bermudagrass varieties with improved yield and nutritive value that varieties currently used in North Florida. Despite Tifton-85 being the common breeding line, there is not enough evidence about which variety will be more efficient for hay production and intensive grazing systems in central and northern Florida. Introduction Bermudagrass is the most planted perennial grass throughout the southeastern of United States. This warm-season grass spreads by rhizome and stolons, and grows in extreme climate conditions. The UF- IFAS Forage group is currently developing and testing new bermudagrass cultivars for Florida. A bermudagrass core collection with > 250 entries was established in 2014 at North Florida Research and Education Center (NFREC) in Marianna, FL. In addition to Marianna, the core collection was also established in Citra, and Ona, FL and in other states including Georgia, North Carolina, and Oklahoma. Materials and Methods The establishment of the bermudagrass varieties was in 2014 (Figure 1) and irrigation was applied during the first weeks of establishment. Application of 10 lb per acre of was used plus an application of micronutrients (10% N, 9.5% as ammoniacal nitrogen and 0.5% as nitrate-n, 10% P 2 O 5, 10% K 2 O, 3% Ca, 2% Mg, 12% S, 0.07% B, 0.25% Mn, 0.10% Zn). Herbage was quantified every 5 weeks from June through September in 2015 and repeated in Disk heights in combination with pasture ruler heights were taken in each variety in the central portion of each plot, to determine forage yield. Harvest was performed using an 11 ft 2 quadrant and clipping at 7 in. The harvested samples were dried at 55 C for 72 h to determine in vitro organic matter (IVOMD). After each harvest the plots were fertilized with 300 lb of Also, in the months of May and September of both years, herbicide was applied on the alleys between plots. In another effort, different commercial bermudagrass varieties were tested, including a potential new release selected in Ona: Bermuda 2000 (Figure 2). This variety trial was replicated in Marianna, Gainesville, and Ona. We are presenting the data obtained in Marianna, FL. Results Herbage accumulation varied with cultivar within each harvest (Figure 3), with some entries presenting earlier production (e.g. Jiggs, Bermuda 2000) than other late types (e.g. Tifton-85). It is important to have different options available for producers. While hay producers might prefer earlier bermudagrass types, to start the production cycle earlier in the year, other producers who overseeded their pastures with coolseason forages, might prefer a late bermudagrass, which stays dormant for a longer period. Overall, the most productive entries in Marianna were Tifton-85, Jiggs, and Bermuda The most productive varieties were not very different from each other in the total production, with an average annual production of 10,000 lbs. DM/acre in a rainfed system. Major differences occurred, however, for forage seasonal distribution Florida Beef Research Report

172 In vitro organic matter digestibility varied along the season and with cultivar (Figure 4). In general, greater IVOMD was observed in the spring compared to mid-summer and fall harvests. Overall, Alicia showed the lowest IVOMD (45%) and Tifton-85 the greatest (54%), with other varieties falling within this range. Bermuda 2000, Coastal, and Jiggs averaged 50% IVOMD. In the near future, new cultivar releases will occur, with the goal of providing producers with elite bermudagrass varieties that fit well in the Florida environment. In North Florida, top varieties included Tifton-85, Jiggs, and Bermuda 2000, with small differences among them in terms of total annual production, however, Jiggs and Bermuda 2000 produced forage earlier in the season, compared to Tifton 85. Figure 1. Core collection of bermudagrass entries at UF-IFAS NFREC, Marianna, FL. Photo credit: Jose Dubeux Florida Beef Research Report

173 Figure 2. Bermudagrass variety trial at UF-IFAS NFREC, Marianna, FL. Photo credit: Jose Dubeux Florida Beef Research Report

174 Dry matter yield (lb./acre) Harvest Alicia Bermuda2000 Coastal FL44 Jiggs Russell Tifton Dry matter yield (lb./acre) Harvest Alicia Bermuda2000 Coastal FL44 Jiggs Russell Tifton 85 Figure 3. Performance of bermudagrass cultivars in Marianna, FL Florida Beef Research Report

175 IVOMD, % Apr-May May-June June-July July-Aug Aug-Sep Oct-Nov Alicia Bermuda 2000 Coastal Jiggs Russel Tifton 44 Tifton 85 Figure 4. In vitro organic matter digestibility (IVOMD) of bermudagrass varieties in Marianna, FL Florida Beef Research Report

176 Florida Beef Research Report

177 Limpograss Performance in North Florida J. Dubeux 1, E. Santos 1, D. Jaramillo 1, L. Garcia 1 Synopsis Limpograss (Hemarthria altissima) is an important grass option in South Florida, however, there is not enough information about limpograss production and stockpiling potential in the Florida Panhandle. Limpograss might be an important alternative along the Gulf Coast to reduce feeding costs and extend the grazing season, considering its adaptation to high water tables, that also prevails in some areas along this region. Introduction Limpograss (Hemarthria altissima) has been successfully adopted in South Florida by livestock producers. This unique grass grows well in flatwood soils and maintains its digestibility for longer periods than other warm-season grasses (e.g. bahiagrass and bermudagrass). Limpograss is also less sensitive to daylength than other grasses, growing during the cool-season, especially in mild-winter like most years in South Florida. After a frost, limpograss will usually be one of the first warm-season grasses to initiate the regrowth. The first cultivars were released in Florida during the 1970s and 80s, and include the diploids Redalta and Greenalta and the tetraploids Bigalta and Floralta (Newman et al., 2014). Recently, two new cultivars were released, Kenhy and Gibtuck. These cultivars present increased grazing tolerance, greater productivity, and nutritive value compared to previously released cultivars (Wallau et al., 2015). Limpograss is often used as stockpiling, considering its slower loss of digestibility compared to other warm-season grasses. The potential of limpograss in North Florida, however, was not fully assessed. Although limpograss collections have been established in North Florida since 2005, a comprehensive evaluation including biomass productivity and nutritive value of the new cultivars was not performed. The persistence of limpograss throughout these years, however, shows the possibility to grow this species in North Florida, despite the cooler temperatures compared to South Florida. Along the Florida Panhandle there are vast areas that can potentially be used with limpograss, especially along the Gulf coast. One of the concerns of growing limpograss in North Florida is the shorter growing season compared to South Florida because of the earlier frost. Comprehensive evaluations are necessary in order to access these potential differences of limpograss performance in contrasting Florida environments. Materials and Methods We established a limpograss trial at UF-IFAS North Florida Research and Education Center (NFREC) in Marianna, FL. Plots were established in July 2014 and included four limpograss germplasm (breeding line 1 and the cultivars Kenhy, Floralta, and Gibtuck). We also included Tifton-85 bermudagrass as a control. Treatments were replicated four times in a randomized complete block design. From May 2015 to Feb 2017, we evaluated biomass productivity and digestibility (IVOMD) of these different grasses. Harvesting started in May of each year, with 5-weeks interval between harvests and 7 inches cutting height. From May to August, after each harvest plots received 60 lb. N/acre, 15 lb. P 2O 5/acre, and 60 lb. K 2O/acre. After August, we simulated a stockpiling scenario letting the plants grow and harvesting only a portion of the plot, every 5 weeks. Therefore, the forage harvested in December, for example, was the cumulative growth since August. Results and Discussion During the summer growth of 2016, forage growth peaked in July with Gibtuck being one of the most productive among limpograss germplasm with comparable growth to Tifton-85 bermudagrass, which is considered one of the most productive bermudagrass available (Figure 1). After August, plants accumulated biomass until December, showing the potential use for stockpiling in North Florida. During Florida Beef Research Report

178 the stockpiling period, Kenhy presented one of the greatest potential. After December, for most cultivars there was not much gain in terms of biomass accumulation (Figure 1). In the second year (May 2016 to Jan 2017), forages peaked earlier in the growing season and declined during the summer. This likely reflects the reduced rainfall combined with the frequent harvesting (5 weeks) compromising the productivity not only of the limpograss, but also of the Tifton-85 bermudagrass. During the stockpiling period, the grasses demonstrated a similar trend to accumulate biomass until December (Figure 2). Digestibility of limpograss was often greater than Tifton-85 bermudagrass, especially during the stockpiling period (Figure 3). Limpograss kept its IVOMD from 55-60% until December 2016, when it significantly reduced it due to colder temperatures and frosts. The growth and digestibility data indicate that limpograss can be used during the summer and as stockpiling at least until December without significantly losing its digestibility. This would be sufficient to fill the November-December forage gap that often occurs along the Panhandle, allowing time for the cool-season forages to produce. As a result, significant reduction of feeding costs would occur, because of reduced need for conserved forages. Conclusions and Implications Limpograss is an alternative for North Florida, providing summer growth and potential use as stockpiling, at least until December. In general, limpograss was more digestible than Tifton-85 bermudagrass, especially during the stockpiling period. Differences among limpograss germplasm occurred, but those differences were not consistent along the two years. Therefore, all the cultivars and the breeding line tested have potential to be used in North Florida. Longer-term evaluation with animal performance is still necessary to fully access limpograss potential in North Florida. Reference: Newman, Y.C., J. Vendramini, L.E. Sollenberger, and K. Quesenberry Limpograss (Hemarthria altissima): overview and management. EDIS SS-AGR-320. Available online at Wallau, M.O et al. Crop Science 55: Florida Beef Research Report

179 Figure 1. Herbage accumulation of limpograss germplasm and Tifton-85 bermudagrass from May 2015 to Jan UF-IFAS NFREC, Marianna, FL Florida Beef Research Report

180 Figure 2. Herbage accumulation of limpograss germplasm and Tifton-85 bermudagrass from May 2016 to Jan UF-IFAS NFREC, Marianna, FL Florida Beef Research Report

181 Figure 3. In vitro organic matter digestibility (IVOMD) of limpograss germplasm and Tifton-85 bermudagrass from May 2015 to Feb UF-IFAS NFREC, Marianna, FL Florida Beef Research Report

182 Research and Graduate Programs The Department has 38 faculty members working in the various disciplines of Nutrition, Breeding and Genetics, Physiology, Molecular Biology, Meat Science and Management. Additionally, there are several faculty members at the outlying Research and Education Centers that participate in our research and graduate programs. The Department offers programs in Master of Science, (thesis and non-thesis) and Doctor of Philosophy. Undergraduate Programs The Department offers three undergraduate degree options; Animal Biology Specialization which is the pre-professional track, Equine Specialization, and Food Animal Specialization. Resources Students have access to an on-campus beef teaching cow herd in addition to two research and production oriented herds close to campus. There are also two additional out-lying Research and Education Centers with nearly 1,000 beef cows of both Bos indicus and Bos taurus breeding available for research and to provide hands-on experience for our students. Extension and the Beef Industry The Department plays an active role in facilitating communication and dissemination of research and production-oriented material to Florida cow-calf producers. Beef producers and state and county faculty work cooperatively in an effort to improve the production, efficiency and marketability of Florida beef cattle. Florida is in a unique position of having more large-scale cow-calf operations than any other state in the United States.