409 - Evaluation of Kemtrace^® Chromium on Animal Performance and Immune System of Weaned Beef Calves

Weaned beef calves are stressed and have a compromised immune system making them highly susceptible to various infections. The study evaluated the effect of feeding chromium supplements on beef calves' performance and immune function. Angus cross beef calves (n = 120) were randomly assigned to pens (n = 12 pens; 6 pens/treatment; 10 calves/pen) in a completely randomized design with subsampling. Calves were fed free-choice Bermuda grass hay, water, and minerals and 2% of BW of 50% soyhulls and 50% corn-gluten mix; dietary treatments used were control (no chromium; n = 60) and chromium-supplemented (0.4% KemTRACE^® chromium; n = 60) during preconditioning trial for 60 days. Calves were weighed on d 0, 30, and 60. Blood samples were collected to perform complete blood counts, serum biochemistry analysis, and pro-inflammatory cytokines (IL-2, TNF-alpha) and anti-inflammatory cytokines (IL-4) measurements using ELISA kits. PHA and COVA challenges respectively assessed cell-mediated and humoral immune responses. Data were analyzed using GLIMMIX procedures of SAS 9.4 (SAS Inst. Inc., Cary, NC) without considering random effect. Results showed that chromium supplementation did not affect the total body weight gain, average daily gain, and feed efficiency of beef calves (P > 0.05). Eosinophil concentration was significantly higher (P < 0.01), and BUN was significantly lower (P < 0.05) in chromium-treated calves. IL-2 was significantly higher (P < 0.05) in chromium-treated than in control calves. TNF-alpha and IL-4 were significantly reduced (P < 0.05) in chromium-supplemented than in control calves. IL-6 was not significantly different (P > 0.05) in chromium-treated than in control calves. Although not significant (P = 0.1), skinfold thickness after the PHA challenge tended to be higher for chromium-treated calves than control groups, which align with a high IL-2 response. Results suggest that chromium supplementation may alter the animals' inflammatory immune response, so it might be considered a suitable feed additive to improve the immune response in the preconditioning calves.