F. M. Ciriaco, D. D. Henry, V. R. G. Mercadante, T. Schulmeister, M. Ruiz-Moreno, G. C. Lamb, N. DiLorenzo

Transcription

1 Effects of Supplementation with a Mixture of Molasses and Crude Glycerol on Performance and Total Tract Digestibility of Beef Heifers Consuming Bermudagrass Hay F. M. Ciriaco, D. D. Henry, V. R. G. Mercadante, T. Schulmeister, M. Ruiz-Moreno, G. C. Lamb, N. DiLorenzo Synopsis Supplementation with energy and protein sources is crucial during critical periods of the year and molasses and crude glycerol combined in a liquid mixture have the potential of serving as an energy supplement for beef cattle consuming forage-based diets. Summary A study was conducted to evaluate the effects of molasses and crude glycerol in a 50:50 liquid mixture on performance and total tract digestibility of beef heifers consuming Tifton 85 bermudagrass hay. Heifers were provided Tifton 85 bermudagrass hay ad libitum and four increasing amounts of the 50:50 mixture were compared: 1) CTRL=0 lb/d; 2) SUP1=1 lb/d; 3) SUP3=3 lb/d; and 4) SUP5=5 lb/d. Twenty-four Angus crossbred heifers were housed at the North Florida Research and Education Center (NFREC) Feed Efficiency Facility (FEF) for 28 d and intake of hay was monitored using the GrowSafe system. The liquid supplement was weighed and offered daily to each animal. Total dry matter intake (DMI) increased linearly as the level of supplementation increased. Hay intake ranged from 1.36 (CTRL) to 1.23% (SUP5) of body weight (BW), and along with final BW was not affected by liquid supplementation. As the liquid supplementation amounts increased, there was a linear increase in average daily gain (ADG; 2.89, 3.02, 3.06, and 3.44 lb for 0, 1, 3, and 5 lb/d of 50:50 mixture, respectively), while feed to gain (F:G) was not affected. Apparent total tract digestibility of dry matter (DM), organic matter (OM), neutral detergent fiber (NDF), and acid detergent fiber (ADF) increased linearly, while crude protein (CP) total tract digestibility decreased linearly as the level of supplementation increased. Increased fiber digestion, along with energy supplementation, led to increased ADG in heifers consuming Tifton 85 bermudagrass hay. Introduction The Southeastern region of the United States has several characteristics that make it unique when compared with other beef cattle regions. The states that represent the southeast and Gulf Coast regions account for 48% of all beef cows in the United States. In the current context of increasing feed input costs, the abundant forage production in the Southeastern U.S. provides an opportunity to decrease the cost of production, considering that feed is the largest cost in a cattle operation. However the predominant forages in this region can be of limited nutritive and often not sufficient to support high levels of production. As a result, there are some critical periods during the year in which there is a need for supplementation with energy and/or protein in cow/calf 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 provide an excellent opportunity to correct nutritional imbalances through strategic supplementation. North Florida Research and Education Center, University of Florida, Marianna, FL

2 The sugar industry is strong in the state of Florida and as a result, byproducts such as molasses have been fed to cattle for decades (Pate and Kunkle, 1989; Kunkle et al., 2000). Crude glycerin (or crude glycerol) is generally recognized as safe (GRAS) animal food ingredient and it can be produced as a coproduct of the soap making industry; however, more recently, the rapid expansion of the biodiesel industry has generated large amounts of crude glycerol as a byproduct, resulting in reduction of prices and increased concerns related to its disposal in the environment, which makes crude glycerol a potential high-energy feed source for cattle (Tan et al., 2013). The objective of this study was to evaluate the effects of different amounts of supplementation with a 50:50 mixture of molasses and crude glycerol on Tifton 85 bermudagrass hay intake, animal performance, and digestibility of nutrients in the total tract of beef heifers. Materials and Methods The study was conducted in April 2013 at the FEF located at the NFREC in Marianna, FL. Liquid supplement was provided by Westway Feed Products (New Orleans, LA). A total of 24 Angus crossbred heifers (weighing average 838±68 lb) were used in the study in a generalized randomized block design. On d 0, heifers were weighed after 16-h feed withdrawal, stratified, and blocked by initial BW (2 blocks: lightest and heaviest), and randomly assigned to one of four treatments on as fed basis: 1. CTRL = no supplementation 2. SUP1 = 1 lb/d of the 50:50 molasses and crude glycerol mixture 3. SUP3 = 3 lb/d of the 50:50 molasses and crude glycerol mixture 4. SUP5 = 5 lb/d of the 50:50 molasses and crude glycerol mixture All heifers were housed in individual pens at the FEF for 28 d and had ad libitum access to water and Tifton 85 bermudagrass hay, which was ground and placed in the feed bunk. The amount of liquid supplement corresponding to each treatment was weighed and offered daily in a plastic container inside the pen to each individual animal. Any unconsumed amount of supplement was weighed and recorded for the first 7 d. By d 8, all heifers were consuming the entire amount of liquid supplement daily, thus no orts recording was needed. After the 14-d adaptation to diets and facility, heifers were weighed and collection of daily feed intake data started. Each pen at the FEF was equipped with two GrowSafe feed bunks (GrowSafe System Ltd., Airdrie, Alberta, Canada) to record intake by weight change measured to the nearest gram. Beginning on d 22 and d 23, feed (hay and liquid) and fecal samples were collected, respectively, for four consecutive d to determine apparent total tract digestibility of DM, OM, CP, NDF, and ADF. Feed samples were collected daily immediately after delivery of liquid supplement. Fecal samples were collected twice daily at 0800 h and 1600 h from the ground, inside the pen, right after the animal defecated. Feed and fecal samples were pooled within heifer and indigestible NDF (indf) was used as an internal indigestible marker. On d 28 heifers were weighed again after withholding feed for 16 h, for evaluation of performance during the entire period. Concentrations of indf in feed and feces were determined as described by Cole et al. (2011) with the following modification: in vitro incubations were conducted for 288 h instead of 96 h using the Daisy II incubator (Ankom Technology, Macedon, NY) to ensure complete digestion of potentially

3 digestible NDF in hay as reported by Krizsan and Huhtanen (2013). Data was analyzed as a generalized randomized block design using the MIXED Procedure of SAS (SAS Institute Inc., Cary, NC). Heifer was considered the experimental unit and the model included the fixed effects of treatment, and the random effect of block. Orthogonal polynomial contrasts were conducted to determine the linear, quadratic, and cubic effects of supplementation level on animal performance or nutrient digestibility. Significance will be determined at P 0.05 and tendencies were considered when 0.05<P Results After ad libitum hay intake was recorded, the liquid supplement represented 0%, 6%, 16%, and 26% of the diet daily DMI (CTRL, SUP1, SUP3, and SUP5, respectively). Chemical composition of Tifton 85 bermudagrass hay and liquid mixture fed to heifers is presented in Table 1. Animal performance is presented in Table 2. Final BW was not affected by liquid supplementation (P 0.10). Total DMI was influenced by liquid supplementation, increasing linearly (P=0.005) as the level of supplementation increased; however, liquid supplementation did not affect (P 0.10) hay DMI. Because hay DMI was not affected by treatment, total DMI was expected to increase as the liquid supplementation increased, considering that the heifers consumed the entire amount of liquid supplement in each treatment. There was a linear increase in ADG (P=0.03) as liquid supplementation amounts increased; however, liquid supplementation did not affect F:G (P 0.10). Nutrient intake and apparent total tract digestibility of nutrients of heifers are presented in Table 3. Liquid supplementation linearly decreased (P 0.05) CP, NDF, and ADF intake, whereas intake of DM and OM were increased linearly (P 0.05). Apparent total tract digestibility of DM, OM, NDF, and ADF increased linearly (P<0.001), whereas apparent total tract digestibility of CP decreased linearly (P=0.002) as the level of supplementation increased. Although it is difficult to separate the contribution of the added supplemental energy to the ADG response from that of the increased fiber digestion, it is likely that the latter contributed significantly considering that hay ranged from 74% (SUP5) to 94% (SUP1) of the total dietary DM consumed by the heifers. We conclude that a 50:50 mixture of molasses:crude glycerol provides a rapidly fermentable source of carbohydrates in the rumen, possibly stimulating microbial growth, consequently increasing fiber digestibility in the total tract. The increase in fiber digestibility, along with energy supplementation, led to an increase in animal ADG. Literature Cited Cole, N. A. et al Prof. Anim. Sci. 27: 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. Krizsan, S. J. and P. Huhtanen J. Dairy Sci. 96: Pate, F. M. and W. E. Kunkle Florida Agricultural Experiment Station. Circular S-365. Tan, H. W. et al Renew. Sustain. Energy Rev. 27:

4 Table 1. Analyzed 1 chemical composition of Tifton 85 bermudagrass hay and liquid supplement fed to beef heifers. Item Hay Liquid Supplement 2 Dry matter (DM), % Organic matter (OM), % DM Crude protein (CP), % DM Neutral detergent fiber (NDF), % DM Acid detergent fiber (ADF), % DM Total digestible nutrients (TDN), % DM Calcium, % DM Phosphorus, % DM Magnesium, % DM Potassium, % DM Sodium, % DM Sulfur, % DM Methanol 3, ppm - <100 1 Analyzed by a commercial laboratory using a wet chemistry package (Dairy One, Ithaca, NY). 2 50:50 mixture (as-fed) of molasses:crude glycerol (Westway Feed Products, New Orleans, LA.) 3 Analyzed by SDK Laboratories (Hutchinson, KS). Table 2. Effects of supplementing increasing amounts of a 50:50 mixture of molasses and crude glycerol on performance of beef heifers fed Tifton 85 bermudagrass hay ad libitum. Treatment 1 Item CTRL SUP1 SUP3 SUP5 SEM 2 Contrast 3 Initial BW, lb NS Final BW, lb NS ADG, lb L Total DMI, lb/d L Hay DMI, lb/d NS Hay DMI, % BW NS F:G NS 1 CTRL: Tifton 85 bermudagrass hay fed ad libitum; SUP1: Tifton 85 bermudagrass hay fed ad libitum + 1 lb/d (asfed) of a 50:50 molasses:crude glycerol mixture; SUP3: Tifton 85 bermudagrass hay fed ad libitum + 3 lb/d (asfed) of a 50:50 molasses:crude glycerol mixture; SUP5: Tifton 85 bermudagrass hay fed ad libitum + 5 lb/d (asfed) of a 50:50 molasses:crude glycerol mixture. 2 Pooled standard error of treatment means, n = 6 heifers/treatment 3 Orthogonal contrast: L = Linear effect of liquid feed supplementation, P 0.05; NS, P 0.10.

5 Table 3. Effects of supplementing increasing amounts of a 50:50 mixture of molasses and crude glycerol on nutrient intake and apparent total tract digestibility of nutrients of heifers fed bermudagrass hay ad libitum. Treatment 1 Item CTRL SUP1 SUP3 SUP5 SEM 2 Contrast 3 4-d Intake, lb/d DM L OM NS CP NS NDF L ADF L Digestibility, % DM L OM L CP L NDF L ADF L 1 CTRL: Tifton 85 bermudagrass hay fed ad libitum; SUP1: Tifton 85 bermudagrass hay fed ad libitum + 1 lb/d (asfed) of a 50:50 molasses:crude glycerol mixture; SUP3: Tifton 85 bermudagrass hay fed ad libitum + 3 lb/d (asfed) of a 50:50 molasses:crude glycerol mixture; SUP5: Tifton 85 bermudagrass hay fed ad libitum + 5 lb/d (asfed) of a 50:50 molasses:crude glycerol mixture. 2 Pooled standard error of treatment means, n = 6 heifers/treatment. 3 Orthogonal contrast: L = Linear effect of liquid feed supplementation, P 0.05; NS, P 0.10.