Effects of trace mineral-fortified, limit-fed preweaning supplements on performance of pre- and postweaned beef calves

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1 Published December 2, 2014 Effects of trace mineral-fortified, limit-fed preweaning supplements on performance of pre- and postweaned beef calves P. Moriel and J. D. Arthington 1 University of Florida IFAS, Range Cattle Research and Education Center, Ona ABSTRACT: Two studies were conducted to evaluate the effects of preweaning limit-fed creep feed (LFC) with or without trace mineral fortification on trace mineral status and pre- and postweaning growth performance of beef calves. At 102 (Exp. 1) and 97 (Exp. 2) d before weaning, Brahman British cow calf pairs (calf age = 142 ± 20 d) were stratified by calving date and randomly allocated into 1 of 8 pastures (approximately 17 pairs/pasture annually; calf BW = 104 ± 5 and 132 ± 25 kg in Exp. 1 and 2, respectively). Treatments were randomly assigned to pastures and consisted of no calf supplementation (Nonsup; 2 pastures/experiment) and limit-fed supplements with (MIN+; 3 pastures/experiment) or without (MIN ; 3 pastures/experiment) trace mineral fortification. Supplements were limit fed in cow exclusion areas 3 times weekly in amounts to provide 0.23 kg/calf daily. In Exp. 1, supplements consisted of compressed cubes (approximately 3.0 by 6.5 cm) whereas in Exp. 2, supplements were offered in a loose meal mixture. At weaning, 15 and 9 heifers/treatment in Exp. 1 and 2, respectively, were randomly selected to be transported (Exp. 1) or to receive an intramuscular injection of porcine red blood cells (PRBC; Exp. 2), each immediately preceding a 28-d feedlot receiving evaluation. In Exp. 1 but not in Exp. 2, LCF increased weaning BW (P = 0.05) compared with Nonsup calves (229 vs. 219 kg; SEM = 4.2). Trace mineral fortification of creep feed decreased DMI of LFC (P < and 0.11 in Exp. 1 and 2, respectively) but did not affect (P 0.53) weaning BW of LFC calves. In Exp. 2 but not Exp. 1, Calves provided LFC had greater (P = 0.040) DMI during the first week postweaning, which was the result of greater (P = 0.040) voluntary DMI of concentrate, compared with Nonsup calves, during this period. In Exp. 2 but not in Exp. 1 (P 0.12), MIN+ increased (P 0.04) liver concentrations of Co, Cu, and Se compared with MIN calves. Preweaning treatment had no effect on serum anti-prbc immunoglobulin titers and plasma concentrations of haptoglobin and ceruloplasmin (P 0.37). Thus, limit-fed creepfeed supplements 1) increased calf weaning BW (Exp. 1), 2) enhanced trace mineral status of weaned calves when supplements were fortified with trace minerals (Exp. 2), and 3) increased voluntary DMI during the first week of the feedlot receiving period (Exp. 2). Key words: beef calves, creep feed, limit fed, stress, trace minerals 2013 American Society of Animal Science. All rights reserved. J. Anim. Sci : doi: /jas INTRODUCTION Unlimited creep feeding has been associated with decreased feed efficiency (Stricker et al., 1979; Faulkner et al., 1994) attributed to less ruminal and total tract NDF digestibility leading to decreased forage use, which could be avoided if creep feeding supplements are limit fed (Cremin et al., 1991). Limit-fed creep-feed (LFC) supplements up to 1.0 kg/d increased preweaning ADG 1 Corresponding author: jarth@ufl.edu Received May 15, Accepted December 9, of calves (Lusby and Wettemann, 1986; Faulkner et al., 1994) and improved concentrate intake in the feedlot (Faulkner et al., 1994). Weaning and transportation are stressful for beef calves, leading to alterations in physiology, immunology, and nutrition (Loerch and Fluharty, 1999). These alterations are related to the activation of the acute phase response (Arthington et al., 2005, 2008), which releases proinflammatory cytokines associated with impaired nutrient metabolism and animal growth (Johnson, 1997). Also, these stressors will impact the trace mineral status of the cattle (NRC, 1996) by liberating tissue stores of Cu, Zn, and Se for the support of immune function, par-

2 1372 Moriel and Arthington ticularly in newly received feeder calves (Duff and Galyean, 2007). Therefore, we hypothesized that LFC could improve the preweaning growth rate of beef calves and could act as a vehicle for the supplementation of trace minerals before the stress response associated with weaning, transportation, and feedlot entry. Our objectives were to evaluate the effects of preweaning trace mineral-fortified, limit-fed supplements on preweaning growth performance of beef calves and on trace mineral status, acute phase response, and growth performance during the feedlot receiving period. MATERIALS AND METHODS All procedures for the both experiments (2010 and 2011) were approved by the University of Florida, Institute of Food and Agricultural Sciences, Animal Research Committee (protocol 001/10ONA). The experiment was conducted at the Range Cattle Research and Education Center (RCREC) at Ona, FL, during the final 102 and 97 d before weaning in mid July for Exp. 1 and 2, respectively. Animals Brahman British cows and calves (initial cow BW = 450 ± 58 and 412 ± 42 kg; cow age = 9 ± 4 and 7 ± 3 yr; calf initial BW = 104 ± 5 and 132 ± 25 kg; calf age = 142 ± 18 and 142 ± 21 d for Exp. 1 and 2, respectively) were stratified by calving date and randomly allocated into 1 of 8 bahiagrass (Paspalum notatum) pastures (n = 139 pairs/ experiment; approximately 17 pairs/pasture). Treatments were randomly assigned to pastures and consisted of no calf supplementation (Nonsup; n = 2 pastures/experiment) and LFC supplements with (MIN+; n = 3 pastures/experiment) or without (MIN ; n = 3 pastures/experiment) trace mineral fortification. Supplements were provided in cow exclusion areas 3 times weekly (Mondays, Wednesdays, and Fridays) in amounts to ensure a maximum target intake (as-fed basis) of 0.23 kg/calf daily. Each of the 8 cowherds were assigned two 8-ha bahiagrass pastures, which they rotated between weekly. Pastures assigned to receive preweaning supplements were fitted with a 6 m 2 grazing exclusion area, constructed in the fenceline, adjacent to the water trough. Thus, a single water trough and grazing exclusion area served both 8-ha pastures. In Exp. 1, supplements consisted of compressed cubes (approximately 3.0 by 6.5 cm) whereas in Exp. 2, supplements were offered in a loose meal mixture. Ingredient and chemical composition of supplements are shown in Tables 1 and 2, respectively. In Exp. 1, all cows and calves were provided free-choice access to plain stock salt with no added trace minerals. In Exp. 2, all cows were provided free choice access to a complete salt-based mineral supplement (Cattle Select Essentials Range, Lakeland Table 1. Nutritional composition of supplements 1 limit fed to calves for 102 and 97 d before weaning for Exp. 1 and 2, respectively Exp. 1 Exp. 2 Item MIN 2 MIN+ 2 MIN MIN+ % (as-fed basis) Cottonseed meal Calcium carbonate Calcium propionate Dehydrated alfalfa meal Ethylediamine dihydroiodide 0.01 Ground corn NaCl Sugarcane molasses Trace minerals Wheat middlings Total Supplements were provided in cow exclusion areas 3 times weekly (Mondays, Wednesdays, and Fridays) in amounts to ensure a maximum target intake (as-fed basis) of 0.23 kg/calf daily. In Exp. 1, supplements consisted of compressed cubes (approximately 3.0 by 6.5 cm) whereas in Exp. 2, supplements were offered in the loose form. 2 Supplements were limit-fed with (MIN+) or without (MIN ) trace minerals fortification. 3 In Exp. 1, trace mineral ingredients were cobalt sulfate, copper sulfate, manganese oxide, sodium selenite, and zinc sulfate whereas in Exp. 2, the ingredients were cobalt sulfate, copper sulfate, iron sulfate, manganese oxide, sodium selenite, and zinc sulfate. Animal Nutrition, Lakeland, FL; 6.0, 0.10, 0.10, 0.30, 63, and 1.0% of Ca, K, Mg, S, NaCl, and P, respectively, and 50, 15,000, 800, 210, 500, 40, and 3000 mg/kg of Co, Cu, Fe, I, Mn, Se, and Zn, respectively) provided in troughs positioned at a height that restricted calf consumption. In Exp. 2, Nonsup calves were offered free-choice access to the complete salt-based trace mineral supplement (Cattle Select Essentials Range) with an average mineral consumption of 20 ± 15 g/calf daily. Hand plucked pasture samples during the preweaning phase were collected in June of each year and preweaning supplements samples for Exp. 1 were collected monthly and pooled for analysis of nutritional value. Samples were sent to a commercial laboratory for DM, CP, TDN, and NDF analysis (Dairy One Laboratory, Ithaca, NY) and for trace minerals concentrations (Diagnostic Center for Population & Animal Health, Lansing, MI). Samples were analyzed by wet chemistry procedures for concentrations of CP (method ; AOAC Int., 2006) and NDF (Van Soest et al., 1991; method for use in an Ankom 200 fiber analyzer; Ankom Technology Corp., Fairport, NY). Calculations of TDN used the equation proposed by Weiss et al. (1992). Chemical composition of supplement in Exp. 2 and preweaning supplement Co and Se concentrations for Exp. 1 were estimated using the feed library of NRC (1996). Body weights were taken on the beginning (d 0) and middle of the preweaning phase (d 60 and 53 for Exp. 1

3 Trace mineral supplementation for beef calves 1373 Table 2. Chemical composition of the supplements 1 and pastures offered to calves for 102 and 97 d before weaning for Exp. 1 and 2, respectively Item 2 MIN 3 MIN+ 3 Pasture MIN MIN+ Pasture Exp. 1 Exp. 2 DM, % DM basis TDN, % CP, % NDF, % Ca, % K, % Mg, % Na, % P, % Co, 2 mg/kg ND Cu, mg/kg Fe, mg/kg Mn, mg/kg Se, 2 mg/kg < Zn, mg/kg Supplements were provided in cow exclusion areas 3 times weekly (Mondays, Wednesdays, and Fridays) in amounts to ensure a maximum target intake (as-fed basis) of 0.23 kg/calf daily. In Exp. 1, supplements consisted of compressed cubes (approximately 3.0 by 6.5 cm) whereas in Exp. 2, supplements were offered in the loose meal form. 2 Preweaning pasture samples from Exp. 1 and 2 and preweaning supplement samples from Exp. 1 were pooled by week and analyzed by a commercial laboratory for DM, CP, TDN, and NDF analysis (Dairy One Laboratory, Ithaca, NY) and for trace mineral concentrations (Diagnostic Center for Population & Animal Health, Lansing, MI). The chemical composition of preweaning supplements in Exp. 2 and Co and Se concentrations of supplements in Exp. 1 were estimated using the feed library of NRC (1996). 3 Supplements were limit-fed with (MIN+) or without (MIN ) trace minerals fortification. 4 ND = not determined. and 2, respectively) and at the time of weaning (d 102 and 97 for Exp. 1 and 2, respectively). Cows were weighed at 0800 h after a 16-h period of water and feed withdrawal. Calves remained with their dams during this period. At weaning, 45 and 27 heifers were randomly selected (15 and 9 heifers/treatment in Exp. 1 and 2, respectively) for the postweaning evaluation. In Exp. 1, the heifers were loaded onto a commercial livestock trailer, immediately after weaning, and transported within the state of Florida for approximately 1,600 km. The heifers remained in the trailer for 24 h before being unloaded at the RCREC feedlot facility. In Exp. 2, the heifers were not transported before feedlot entry; however, on d 0 relative to feedlot entry, all heifers received a 10-mL intramuscular injection of porcine red blood cells (PRBC; Lampire Biological Laboratories, Pipersville, PA) solution (25% PRBC and 75% sterile PBS; Amresco, Solon, OH) to elicit an antigen-induced humoral immune response. Before feedlot entry, heifers were stratified by BW within each treatment and randomly assigned by treatment to 1 of 15 or 9 pens (5 and 3 pens/treatment for Exp. 1 and 2, respectively; 3 heifers/pen). Heifers remained in the feedlot for 30 and 29 d in Exp. 1 and 2, respectively. In both experiments, heifer BW was measured at the start and end of the feedlot receiving period after a 16-h period of water and feed withdraw, except for BW at feedlot entry in Exp. 1, which was obtained 24 h after heifers were loaded into the trailer (d 1). Heifers were provided free-choice access to a grain-based concentrate, stargrass (Cynodon nlemfuensis) hay, and a complete commercial mineral/vitamin mix (Cattle Select Essentials Range; described previously) throughout the feedlot period. Daily DMI was determined by subtracting the DM of the daily refusal from the DM of the daily offer of both hay and concentrate, which were offered free choice at the opposite ends of the feed bunk. Feed DM was determined by drying daily samples in a forced-air oven at 55 C for 48 h. Daily samples of hay and concentrate were pooled by week and submitted to a commercial laboratory for DM, CP, TDN, ADF, and NDF analysis (Dairy One Laboratory) and for trace mineral concentrations (Diagnostic Center for Population & Animal Health). Samples were analyzed by wet chemistry procedures for concentrations of CP, TDN, NDF (described previously), and ADF (method modified for use in an Ankom 200 fiber analyzer; Ankom Technology Corp.; AOAC Int., 2006). Chemical composition of supplements and hay offered during the postweaning phase are shown in Table 3.

4 1374 Moriel and Arthington Table 3. Chemical composition of the concentrate and hay offered to calves for 30 and 28 d relative to feedlot entry in Exp. 1 and 2, respectively 1,2 Exp. 1 Exp. 2 Item Concentrate Hay Concentrate Hay DM, % DM basis, % TDN CP NDF ADF Ca P Supplements (as-fed basis) in Exp. 1 consisted of 49.0% soybean hulls, 30.3% wheat middlings, 12.2% dried distillers grain, 4.5% molasses, 0.80% calcium carbonate, and 3.2% canola pellets. Supplements in Exp. 2 consisted of 0.50% Ca carbonate, 8.0% citrus pulp pellets, 7.8% corn meal, 15.0% cottonseed hulls, 15.7% cottonseed meal, 7.8% cracked corn, 8.0% dried distillers grain plus soluble, 0.04% lasalocid (Bovatec 90; Alpharma Inc., Fort Lee, NJ), 2.0% molasses, 21.0% soybean hulls, 5.4% soybean meal, 0.06% trace mineral and vitamin premix, and 8.7% wheat middlings. 2 Concentrate and hay samples were pooled by week and analyzed by a commercial laboratory for DM, CP, TDN, ADF, and NDF (Dairy One Laboratory, Ithaca, NY) and Ca and P concentrations (Diagnostic Center for Population & Animal Health, Lansing, MI). 3 Estimated using the equation proposed by Weiss et al. (1992). Blood Sampling, Liver Biopsy, and Laboratory Analyses Preprandial blood samples were taken from the jugular vein on d 0, 1, 5, 9, 16, 23, and 30 (Exp. 1) and d 0, 1, 3, 6, 14, 21, and 28 (Exp. 2) relative to feedlot entry. Blood samples were collected into 2 commercial blood collection tubes (Vacutainer, 10 ml; Becton Dickinson, Franklin Lakes, NJ) with and without an anticoagulant. Blood samples were placed on ice immediately after collection and centrifuged at 1200 g for 30 min at 4 C for serum and plasma collection. Plasma and serum were frozen at 20 C on the same day of collection. Plasma haptoglobin (Hp) concentrations were determined in duplicate samples by a biochemical assay measuring haptoglobin-hemoglobin complexing by the estimation of differences in peroxidase activity (Makimura and Suzuki, 1982). Results were obtained as arbitrary units resulting from the absorption reading at 450 nm. Same quality control standards used in the biochemical assay were analyzed by quantitative determination of bovine Hp in plasma (bovine haptoglobin ELISA test kit; Life Diagnostics, Inc., West Chester, PA). The concentrations of Hp, based on the ELISA assay, ranged from 0.03 (low control) to 0.95 mg/ml (high control) with an intra-assay CV of 1.26%. The ELISA standard curve was used to convert the arbitrary units obtained from the biochemical procedures into milligrams per milliliter (Cooke and Arthington, 2012), with the lowest detectable value of 0.03 mg/ml. Inter- and intra-assay CV of Hp concentrations using the biochemical procedure were 3.62 and 3.84%, respectively. Plasma ceruloplasmin (Cp) oxidase activity was measured in duplicate samples by using the colorimetric procedures described by Demetriou et al. (1974). Ceruloplasmin concentrations were expressed as milligrams per deciliter as described by King (1965). Inter- and intra-assay CV for Cp concentrations were 4.95 and 2.26%, respectively. In Exp. 2, hemagglutination to PRBC was determined by the procedure adapted from Engle et al. (1999). Serum samples were heat inactivated in a 56 C water bath for 30 min. Total immunoglobulin titers were determined using 96-well round bottom cell-culture plates (Fisher Scientific, Suwanee, GA). Twenty-five microliters of sterile PBS (ph 7.4) was added to the wells followed by 25 μl of heat-inactivated serum. The plates were incubated for 30 min at 37 C, after which 25 ml of PBS was added to the remaining wells. Twenty-five microliters of a 2.0% PRBC suspension was added to all wells, and the plates were incubated for 30 min at 37 C. Plates were read at 450 nm immediately after incubation, and the titers were read and recorded as log 2 PRBC titers, corresponding to the total anti-prbc immunoglobulin titers. Inter- and intra-assay CV for anti-prbc immunoglobulin titers concentrations were 3.78 and 3.74%, respectively. Liver biopsies were collected on d 9 and 6 relative to feedlot entry in Exp. 1 and 2, respectively. Samples were collected from 1 and 2 randomly selected heifers/pen (3 and 6 sampled heifers in Exp. 1 and 2, respectively). After collection, samples were frozen at 80 C and sent to Michigan State University (Animal Health Diagnostic Laboratory, Lansing, MI) for analysis of trace mineral concentration using inductively coupled plasma atomic emission spectroscopy as described by Braselton et al. (1997). Statistical Analyses Statistical analyses were conducted separately for each experiment. This approach was chosen due to the differences in treatment formulation and delivery method. Data were analyzed as a completely randomized design using the MIXED procedure (SAS Inst. Inc., Cary, NC) with Satterthwaite approximation to determine the denominator degrees of freedom for the test of fixed effects. Calf age at the beginning of the study (d 0) was used as a covariate in the pre- and postweaning growth analyses. Calf BW was adjusted for sex before analysis. The effects of treatment on BW, BW gain, and ADG during the preweaning phase were tested using pasture as the experimental unit and pasture(treatment) as the random effect. Supplement intake was analyzed as a repeated measure using the MIXED procedure of SAS with pasture(treatment) as the

5 Trace mineral supplementation for beef calves 1375 subject and random effect and with Satterthwaite approximation. Covariance structure was determined using the lowest Akaike information criterion. The autoregressive 1 covariance structure was used for supplement intake analysis. The effects of treatment on BW, BW gain, and ADG during the postweaning phase were tested using pen as the experimental unit and pen(treatment) as the random effect. Concentrate, hay, and total DMI, plasma Cp, Hp, and anti- PRBC immunoglobulin titers during the receiving period were analyzed as repeated measures using the MIXED procedure of SAS with heifer(pasture) as the subject and with Satterthwaite approximation. For concentrate, hay, and total DMI, data were sorted into 2 periods (d 0 to 6 and d 7 to 30 relative to feedlot entry) and analyzed separately. Pasture(treatment) and calf(pasture) were included as random effects for the analysis of plasma concentrations of Cp, Hp, and anti-prbc immunoglobulin titers. The autoregressive and unstructured covariance structures were used for plasma Cp concentrations in Exp. 1 and 2, respectively. The unstructured covariance structure was used for plasma Hp concentrations in Exp. 1 and 2. The compound symmetry covariance structure was used for the serum anti-prbc immunoglobulin titers. All results were reported as least-squares means. Repeated measures data were separated using the LSD multiple comparison test if a significant preliminary F-test was detected (P < 0.05). All remaining data were tested using single degree of freedom orthogonal contrasts to compare to effects of creep feeding (Nonsup vs. MIN+ and MIN ) and trace mineral fortification (MIN vs. MIN+). Significance was set at P 0.05, and tendencies if P > 0.05 and Results are reported according to main effects when interactions were not significant. Preweaning Phase RESULTS AND DISCUSSION Initial calf BW at the beginning of the preweaning phase did not differ (P 0.15) among treatments (mean initial BW = 132 ± 3.8 and 133 ± 3.9 kg for Exp. 1 and 2, respectively; Table 4). However, in Exp. 1 but not in Exp. 2, BW at the end of the preweaning phase was greater (P = 0.05) for LFC calves compared with Nonsup calves (229 vs. 219 kg ± 4.20 kg, respectively; Table 3). These results are in agreement with Lusby and Wettemann (1986) who reported greater BW gain when calves were limit fed 0.45 kg/d of soybean meal compared with nonsupplemented calves. In our study, the greater BW of LFC calves in Exp. 1 can be attributed to the numerically greater ADG during the first 60 d of creep feeding compared with Nonsup calves (1.10 vs kg/d; SEM = 0.075; Table 4). Similarly, calves limit fed 1.0 kg/d of corn or soybean hulls Table 4. Preweaning growth performance of cows and calves receiving no supplement (Nonsup) or limit-fed creep-feeding supplements, with (MIN+) or without (MIN ) trace mineral fortification 1 Treatment 2 SEM 3 Contrast 4 Item Exp. Nonsup MIN MIN+ 1 2 Calf BW, kg d d d Calf ADG, kg/d d 0 to d 60 to d 0 to Cow BW, kg d d Cow ADG, kg/d d 0 to Calf BW, kg d d d Calf ADG, kg/d d 0 to d 53 to d 0 to Cow BW, kg d d Cow ADG, kg/d d 0 to Least square means. 2 Supplements were provided in cow exclusion areas 3 times weekly (Mondays, Wednesdays, and Fridays) in amounts to ensure a maximum target intake (as-fed basis) of 0.23 kg/calf daily. In Exp. 1, supplements consisted of compressed cubes (approximately 3.0 by 6.5 cm) fed for 102 d before weaning whereas in Exp. 2, supplements were offered in a loose meal form for 97 d before weaning. 3 n = 139 pairs/experiment randomly assigned to 1 of 8 pastures (approximately 17 pairs/pasture). 4 Contrast 1 = Nonsup vs. MIN and MIN+; Contrast 2 = MIN vs. MIN+. for 111 d before weaning had 39% greater ADG than noncreep-fed calves (Faulkner et al., 1994). In Exp. 1, treatment, week, and treatment week effects were detected (P < 0.001) for preweaning supplement DMI, where supplement DMI of MIN calves gradually increased from wk 3 to 9 and were greater (P 0.004; largest SEM = 0.01) than MIN+ calves, which never reached the target maximum supplement DMI of 0.23 kg/calf daily (Fig. 1a). Consequently, overall mean supplement DMI was greater (P < 0.001) for MIN calves than MIN+ calves (0.16 vs kg/calf daily, respectively; SEM = kg). Differences in supplement DMI may be due to a reduction in palatability of the fortified

6 1376 Moriel and Arthington Figure 1. Least square means of preweaning, creep-feed supplement DMI of calves limit-fed supplements with (MIN+) or without (MIN ) trace mineral fortification for 102 (Exp. 1) and 97 d (Exp. 2) before weaning. Cows and calves were randomly assigned to 1 of 8 pastures (n = 139 pairs/experiment; approximately 17 pairs/pasture). Supplements were offered as a compressed cube in Exp. 1 and in a loose meal mixture in Exp. 2. In Exp. 1, a treatment week effect was detected (P < 0.001) for supplement intake. From wk 3 to 14, MIN calves had greater (P 0.01; largest SEM = 0.01) supplement DMI compared with MIN+ calves. In Exp. 2, a treatment week effect was not detected (P = 0.27) for supplement DMI; however, MIN calves tended (P = 0.11) to have greater mean supplement DMI compared with MIN+ calves (0.19 vs kg/calf daily for MIN and MIN+ calves, respectively). * P Pooled SEM = and for Exp. 1 and 2, respectively. cubes. Interestingly, MIN+ calves had similar (P 0.27; Table 3) weaning BW and overall ADG compared with MIN calves, despite the differences in supplement DMI. Similarly, MIN calves in Exp. 2 tended (P = 0.11) to have greater mean supplement DMI compared with MIN+ calves (0.19 vs kg/calf daily; SEM = 0.009), which further supports the assumption of calves having an aversion to the trace mineral-fortified supplements. This is an important issue that should be considered when designing mineral-fortified supplements for young beef calves during the preweaning phase. Postweaning Phase Weaning, transportation, and feedlot entry are stressful events for a feeder calf (Arthington et al., 2008). These events affect the physiology, immunology, and nutrition of the calf, with the most significant impact of stress on feed intake and immunocompetency (Loerch and Fluharty, 1999). Preweaning supplementation increased voluntary postweaning DMI (% of BW) during the first week in Exp. 2 (P = 0.04; Table 5). The majority of this response was the result of greater concentrate DMI of calves receiving LFC preweaning. Occurring in Exp. 2 but not Exp. 1 implies that the form of LFC supplement may have impacted the postweaning desire of the calves to consume concentrate, because the meal form of LFC in Exp. 2 (preweaning) was similar to the meal form of concentrate offered postweaning. In contrast, the LFC in Exp. 1 was compressed cubes, which differed in shape and texture compared with the meal form of concentrate offered postweaning. This supposition is supported by Fluharty and Loerch (1996) who reported that calves newly arrived at the feedlot initially preferred a diet that was similar in moisture and texture to feeds they were familiar with previously. Our results are also in general agreement with Arthington et al. (2008), which showed that, when given free access to hay and concentrate separately, calves previously familiarized with concentrate had a greater proportional intake of concentrate vs. hay during the first week in the feedlot. Most health problems with newly received calves occur within the first 2 wk; therefore, adequate nutrient intake during the first week of feedlot entry is critical for stress recovery and disease resistance (Loerch and Fluharty, 1999). In our experiments, preweaning treatments did not affect (P 0.31) BW change or ADG of heifers during the feedlot receiving period, despite greater DMI during the first week of the receiving period (Exp. 2 only; Table 6). These results are in agreement with others (Stuedemann et al., 1968; Martin et al., 1981; Faulkner et al., 1994) but contrary to Arthington et al. (2008), who observed greater mean ADG of calves offered unlimited creep feeding or preweaned at the ranch of origin for 45 d before transport compared with control calves receiving no preweaning supplementation. Interestingly, heifers in Exp. 1 gained BW whereas heifers in Exp. 2 lost BW during the receiving period. The reason for this response is unknown. In Exp. 1, the processing facility was directly adjacent to the feedlot (<15 m) whereas in Exp. 2, heifers had to be loaded in a trailer and transported approximately 1.6 km to another processing facility on each day of sample collection. Although this distance is relatively short, the loading and transporting may have been an additional source of stress to these heifers. Loading and transport, even for only 30 min, results in increased plasma concentrations of cortisol and epinephrine (Locatelli et al., 1989; Agnes et al., 1990), and simply regrouping acclimated feedlot cattle increases plasma cortisol concentrations (Gupta et al., 2005). In addition, during the receiving period, heifers in Exp. 2 had numerically less total DMI compared with heifers in Exp. 1 (2.11 vs. 2.53% of BW; largest SEM = 0.15), which is likely attributed to the added stress of transportation.

7 Trace mineral supplementation for beef calves 1377 Table 5. Postweaning concentrate, hay, and total DMI in the feedlot of heifers receiving no supplementation (Nonsup) or limit-fed creep-feeding supplements with (MIN+) and without (MIN ) trace mineral fortification for 102 and 97 d before weaning (Exp. 1 and 2, respectively) Treatment 2 SEM 3 Contrasts 4 Item 1 Experiment Nonsup MIN MIN+ 1 2 Concentrate DMI, % of BW d 0 to d 7 to Hay DMI, % of BW d 0 to d 7 to Total DMI, % of BW d 0 to d 7 to Concentrate DMI, % of BW d 0 to d 7 to Hay DMI, % of BW d 0 to d 7 to Total DMI, % of BW d 0 to d 7 to Relative to feedlot entry. 2 During the preweaning phase calves received no supplementation (Nonsup) or were limit-fed supplements, with (MIN+) or without (MIN ) trace mineral fortification, for 102 and 97 d before weaning in Exp.1 and 2, respectively. During the postweaning, feedlot receiving period, heifers were provided free-choice access to a grain-based concentrate and stargrass (Cynodon nlemfuensis) hay (Table 3) and a complete commercial mineral/vitamin mix. 3 n = 45 (15/treatment) and 27 (9/treatment) heifers in Exp. 1 and 2, respectively. 4 Contrast 1 = Nonsup vs. MIN and MIN+; Contrast 2 = MIN vs. MIN+. Trace minerals are important for the support of immune function, health, and performance of stressed feeder cattle (Duff and Galyean, 2007). Weaning and transportation cause stress responses that decrease feed intake, which suggests that greater dietary trace mineral concentrations should be formulated into the diets offered to stressed feeder calves (NRC, 1996). Trace mineral fortification of preweaning supplements impacted liver trace mineral concentrations of calves after feedlot entry. Although the majority of liver trace mineral concentrations did not differ (P 0.12) among treatments in Exp. 1, MIN+ calves had greater (P = 0.05) liver concentrations of Fe and numerically greater liver concentrations of Cu and Zn compared with MIN and Nonsup calves (Table 7). In Exp. 2, Nonsup calves had greater liver concentrations of Cu (P = 0.04) and tended to have greater liver concentrations of Zn (P = 0.09) compared with the average of MIN and MIN+ calves. However, MIN+ calves had greater liver concentrations of Co (P = 0.03), Cu (P = 0.04), and Se (P = 0.02) and tended to have greater liver concentrations of Fe (P = 0.09) compared with MIN calves (Table 8). In Exp. 2 but not in Exp. 1, Nonsup calves had free access to a salt-based trace mineral supplement with intake measured weekly. Thus, the supplemental trace mineral intake (mg/d) of MIN+ calves was greater than MIN calves, with Nonsup calves having an intermediate intake of trace minerals (Table 9). It is important to note, however, that the magnitude of differences in Co, Cu, and Se intake in Exp. 2 was numerically greater than in Exp. 1, which can explain the lack of differences in liver trace mineral concentrations between calves receiving preweaning supplements with or without trace mineral fortification in Exp. 1. Liver concentrations of all elements were considered adequate for all treatments in both studies (Underwood and Suttle, 1999; McDowell and Arthington, 2005). Activation of the acute phase protein reaction (APR) is a normal immunological reaction to stress stimuli, such as weaning. The response is characterized by increased concentrations of circulating proinflammatory cytokines (Klasing and Korver, 1997) and acute phase proteins (Arthington et al., 2008), which affect nutrient metabolism and animal growth (Johnson, 1997). Creep feeding (Fluharty and Loerch, 1996) has been shown to reduce the incidence of morbidity in newly received feeder calves and the magnitude of the APR is greater for morbid vs. healthy calves (Carter et al., 2002). However, healthy calves still undergo the APR as a result of weaning and transportation (Arthington et al., 2008). The magnitude of the APR may be a key indicator of subsequent productivity in the feedlot, especially during the receiving period

8 1378 Moriel and Arthington Table 6. Postweaning growth performance during a 30-d feedlot receiving period heifers receiving no preweaning supplementation (Nonsup) or limit-fed creep-feeding supplements with (MIN+) or without (MIN ) trace mineral fortification (Exp. 1 and 2) 1 Treatment 2 SEM 3 Contrast 4 Item Exp. Nonsup MIN MIN+ 1 2 BW, 5 kg d < d < BW change, kg ADG, kg/d BW, kg d d BW change, kg ADG, kg/d Heifers were provided free-choice access to grain-based concentrate and stargrass (Cynodon nlemfuensis) hay (Table 3) and a complete commercial mineral/ vitamin mix. 2 During the preweaning phase, calves received no supplement (Nonsup) or were limit-fed supplements with (MIN+) or without (MIN ) trace mineral fortification for 102 and 97 d before weaning (Exp. 1 and 2). 3 n = 45 (15/treatment) and 27 (9/treatment) heifers in Exp. 1 and 2, respectively. 4 Contrast 1 = Nonsup vs. MIN and MIN+; Contrast 2 = MIN vs. MIN+. 5 Relative to feedlot entry. (Arthington et al., 2005; Qiu et al., 2007). This response was also evident in the current studies where a postweaning APR was detected. Plasma Hp concentrations were not affected (P 0.49) by preweaning treatments. However, a day effect was detected (P 0.004) for plasma Hp concentrations in both experiments (Fig. 2), which increased on d 1 to 3 and returned to baseline concentrations on d 9 relative to feedlot entry. Likewise, Arthington et al. (2008) reported Hp concentrations of feeder calves increasing on d 1 and returning to baseline concentrations by d 9 relative to feedlot entry. Ninety to ninety-five percent of serum Cu is associated with Cp (Cousins, 1985). Despite the differences in liver Cu concentrations among treatments in Exp. 1 and 2, plasma Cp concentrations Table 7. Liver mineral concentrations of heifers receiving no preweaning supplement (Nonsup) or limit-fed creepfeeding supplements with (MIN+) or without (MIN ) trace mineral fortification (Exp. 1) 1 Treatment 2 SEM 3 Contrast 4 Item Nonsup MIN MIN+ 1 2 mg/kg (DM basis) Co Cu Fe Mn Mo Se Zn Least square means. 2 During the preweaning phase, calves received no supplement (Nonsup) or were limit-fed supplements with (MIN+) or without (MIN ) trace mineral fortification for 102 d before weaning. During the postweaning phase, heifers were provided free-choice access to grain-based concentrate and stargrass (Cynodon nlemfuensis) hay (Table 3) and a complete commercial mineral/ vitamin mix. Liver biopsy samples were collected on d 9, relative to receiving feedlot entry. 3 n = 15 total samples (1 sampled heifer/pen; 3 heifers/treatment). 4 Contrast 1 = Nonsup vs. MIN and MIN+; Contrast 2 = MIN vs. MIN+. Table 8. Liver mineral concentrations of heifers receiving no preweaning supplement (Nonsup) or limit-fed creepfeeding supplements with (MIN+) or without (MIN ) trace mineral fortification (Exp. 2) 1 Treatment 2 SEM 3 Contrast 4 Item Nonsup MIN MIN+ 1 2 mg/kg (DM basis) Co Cu Fe Mn Mo Se Zn Least square means. 2 During the preweaning phase, calves received no supplement (Nonsup) or were limit-fed supplements with (MIN+) or without (MIN ) trace mineral fortification for 97 d before weaning. During the postweaning phase, heifers were provided free-choice access to grain-based concentrate and stargrass (Cynodon nlemfuensis) hay (Table 3) and a complete commercial mineral/ vitamin mix. Liver biopsy samples were collected on d 9, relative to receiving feedlot entry. 3 n = 18 total samples (2 sampled heifer/pen; 6 samples/treatment). 4 Contrast 1 = Nonsup vs. MIN and MIN+; Contrast 2 = MIN vs. MIN+.

9 Table 9. Trace mineral intake from preweaning creep supplements and salt-based mineral supplements in calves receiving no supplementation (Nonsup) or limit-fed creep-feed supplements with (MIN+) or without (MIN ) trace mineral fortification 1 Treatment 3 SEM 4 Contrast 5 Item 2 Exp Nonsup MIN MIN+ 1 2 mg/d Co Cu Fe <0.001 Mn Se Zn Co <0.001 Cu <0.001 Fe 2 ND < Mn Se <0.001 Zn <0.001 Trace mineral supplementation for beef calves Least square means. 2 Trace mineral intake was estimated by multiplying the average supplement intake of each pasture by the mineral concentration in the supplement (DM basis). 3 During the preweaning phase calves received no supplement (Nonsup) or were limit-fed supplements with (MIN+) or without (MIN ) trace mineral fortification for 102 and 97 d before weaning (Exp. 1 and 2). In Exp. 2 but not Exp. 1, calves assigned to the Nonsup treatment were provided free-choice access to a salt-based mineral supplement throughout the preweaning phase (average mineral consumption = 20 ± 15 g/calf daily). 4 n = 139 pairs randomly assigned to 1 of 8 pastures (approximately 17 pairs/ pasture). 5 Contrast 1 = Nonsup vs. MIN and MIN+; Contrast 2 = MIN vs. MIN+. 6 ND = not determined. Figure 2. Plasma concentrations of haptoglobin (Hp) and ceruloplasmin (Cp) of weaned heifers [n = 45 (15/treatment) and 27 (9/treatment) in Exp. 1 and 2, respectively]. In Exp. 1 and 2, treatment and treatment day effects were not detected (P 0.16) for plasma concentrations of Hp and Cp; however, a day effect was detected (P 0.004). Plasma Hp concentrations in both experiments increased on d 1 to 3 and returned to baseline concentrations on d 9 relative to receiving feedlot entry (SEM = and for Exp. 1 and 2, respectively). Plasma Cp concentrations peaked on d 9 and 6 and returned to baseline concentrations on d 30 and 28 for Exp. 1 and 2, respectively (SEM = 0.80 and 2.07 for Exp. 1 and 2, respectively). were not affected (P 0.16) by trace-mineral fortification of preweaning supplements. However, time effects were detected (P < ) for plasma Cp concentrations in Exp. 1 and 2 (Fig. 2). Plasma Cp concentrations peaked on d 9 and 6 and returned to baseline concentrations on d 30 and 28 for Exp. 1 and 2, respectively. To evaluate the humoral response of the calves, total serum anti-prbc titers were measured in Exp. 2, but treatment (P = 0.68) and treatment day effects (P = 0.80) were not detected. However, a day effect was detected (P < 0.001) with serum anti-prbc titers peaking on d 6 and gradually decreasing to d 28. A similar PRBC immunoglobulin titer response was observed by Engle et al. (1999), who showed total PRBC immunoglobulin titers peaking on d 7 and decreasing through d 21 in Angus steers (7 mo of age) fed a corn silage-based diet. Ward and Spears (1999) injected Angus bull calves with 90 mg of copper glycinate 28 d before weaning and subsequently supplemented these calves with CuSO 4 at 5.0 and 5.5 mg of Cu/kg of DM. They observed greater PRBC antibody titers with increasing supplemental Cu. Furthermore, Arthington and Havenga (2012) observed an increase in bovine herpesvirus-1 antibody titers of beef steers treated with injectable trace minerals compared with calves injected with sterile saline at the time of vaccination. Although these aforementioned studies reported a response of trace mineral on hummoral immunity, the lack of a response, as reported in the current study, is not uncommon. Other studies have shown variable results on growth and immune response of feeder beef calves due to trace mineral nutrition (Droke and Loerch, 1989; Clark et al., 2006). In conclusion, limit-fed preweaning supplements resulted in greater calf BW at weaning in Exp. 1 but not in Exp. 2 compared with nonsupplemented calves. Difference between experiments is likely attributed to differences in formulation and subsequent DMI of preweaning supplements. In addition, limit-fed creep-feeding supplements were effective in increasing voluntary DMI in the first week of the receiving period in Exp. 2 compared with nonsupplemented calves. Furthermore, trace mineral fortification of preweaning supplements enhanced liver trace mineral concentrations of Co, Cu, and Se of weaned

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