136 How frequency of supplementation containing rumen protected fat affects serum fatty acid profiles in beef heifers. (1st February 2016)

• Record Type: Journal Article
• Authors: Cook, E. K.; Ricks, R. E.; Duckett, S. K.; Long, N. M.
• Is Part Of: Journal of animal science. Volume 94(2016)Supplement 1
• Page Start: 66
• Page End: 66
• Publication Date: 2016-02-01
• Subjects: Serum fatty acids -- Rumen protected fat -- Supplementation frequency; Livestock -- Periodicals; Livestock; Electronic journals; Periodicals; 636.005
• DOI: 10.2527/ssasas2015-136
• Languages: English
• ISSNs: 0021-8812

Abstract

Abstract: Studies have shown that daily supplementation of rumen protected fats (RPF) is optimal for lactating dairy cows; however, the optimal frequency of supplementation for growing beef animals in unknown. The study's purpose was to determine if supplementation frequency of RPF (Megalac-R) influences BW, BCS, and circulating serum fatty acids (FA) in growing heifers. Twelve early gestation beef heifers (∼60 d of gestation) were supplemented 0.5 kg corn gluten feed daily with access to grazing and hay during a 3-wk adaptation period (AD). During the last 3 d of the adaptation period, blood samples were collected immediately before supplementation, then 8 and 16 h post-supplementation. Subsequently, each heifer was randomly assigned to one of 3 supplementation frequency treatments of RPF for 3 wk in a Latin square design with 3 periods: 3 d/wk (3D), 5 d/wk (5D), or 7 d/wk (7D), with each treatment receiving the same amount of RPF and corn gluten feed per wk. Blood samples were collected during the final 3 d of the supplementation period as in the adaptation period. Serum FA profiles were analyzed on a random subsample of 8 heifers. Heifer BW and BCS changes, along with serum FA profiles, were analyzed using the MIXED procedure of SAS. Heifer BW and BCS changes during the 3 wk period were similar ( P > 0.39) between treatments (9, 13, and 10 kg SEM 3 kg; 0, 0, and −0.1 BCS units SEM 0.1; 3D, 5D and 7D respectively). Serum concentrations of 18:2 were increased during supplementation compared to the adaptation period (trt*day*time effect P = 0.04). However, there was no difference between supplementation frequencies within a day*time period. Total serum FA concentrations had a trt*day*time interaction ( P = 0.01). Heifers supplemented with RPF had increased serum FA compared to when non-supplemented. There were also decreases in serum FA between the supplementation frequencies over the course of the 3-d sampling period. These results demonstrate that supplementation of RPF during early gestation improves serum FA profiles of beef heifers, specifically increasing concentrations of both 18:2 and total serum FA. However, these improvements do not appear to be dependent on the frequency of RPF supplementation.