PS1-27. Effects of Dried Distillers Grains and Whole Cottonseed Supplementation on Growth, Rumen Fermentation, and Immune–inflammatory Responses of Brangus Steers.

Abstract

This experiment evaluated the effects of dried distillers grains (DDG) and whole cottonseed (WCS) supplementation on growth, rumen fermentation, and immune–inflammatory responses of Brangus steers during preconditioning. Seventy-two steers (267 ± 31.3 kg BW) were assigned to 1 of 2 treatments (4 pastures/treatment; 9 steers/pasture): 1) DDG or 2) WCS, supplemented daily at 0.3% BW with ad libitum bermudagrass hay. A lipopolysaccharide (LPS) challenge was conducted on day 63 to evaluate inflammatory and immune responses. Body weight was collected on days 0, 28, and 63; rumen fluid on days 0 and 56; and blood samples on days 0, 28, and 63 (0 and 4 hours post-LPS) and day 64 (24 hours post-LPS). Rectal temperature, respiration rate, and sickness behavior were recorded up to 24 hours post-LPS. Pasture was considered the experimental unit, and data was analyzed as repeated measures using the MIXED procedure of SAS. Final BW was greater (P < 0.01) in DDG vs WCS steers (302 vs. 290 ± 1.28 kg). Rumen pH and volatile fatty acid concentrations were not affected (P ≥ 0.45) by treatments. Plasma gossypol was undetectable in DDG steers but increased over time (P < 0.01) in WCS steers. Serum insulin-like growth factor-1 was greater (P < 0.01) on day 63 (0 and 4 h post-LPS) and day 64 in DDG vs WCS steers. Serum insulin was lower (P = 0.04), and cortisol tended to be greater (P = 0.09) in DDG vs WCS steers. Furthermore, DDG steers had greater (P = 0.04) serum urea nitrogen on day 63 (0 hour post-LPS), lower (P = 0.02) cholesterol on day 63 (0 and 4 hours post-LPS) and day 64, and tended to have greater (P = 0.07) non-esterified fatty acids. Moreover, DDG steers had lower (P = 0.01) serum alanine aminotransferase on day 63 (0 hour post-LPS) and greater (P = 0.05) gamma-glutamyl transferase. No other serum biochemistry variables differed between treatments (P ≥ 0.23), and neither rectal temperature, respiration rate, nor sickness behavior was affected (P ≥ 0.45). Several plasma cytokines tended to be greater (P ≤ 0.10) in DDG steers, including interferon-γ, interferon-α, interleukin-1F5, and interferon-γ–inducible protein-10. Additionally, DDG steers had greater (P = 0.01) plasma macrophage inflammatory protein1-β on day 63 (0 h post-LPS) and day 64. In summary, DDG supplementation enhanced growth and promoted a more pronounced immune–inflammatory activation than WCS, while rumen fermentation remained similar across supplements. Although WCS increased plasma gossypol concentrations, no biochemical indicators of liver damage were observed.