Effects of amino acid supplementation on innate and adaptive immune response and performance in growing beef cattle

Tissue catabolism in the disease state may be due to AA inadequacies relative to AA demand by the immune system. Four experiments were conducted to determine the effect of supplemental Arg, Ile, Leu, and Val on immune function and growth. In Exp 1, 20 steers were used in a random complete block experiment using abomasal Arg infusion and lipopolysaccharide (LPS) challenge (2 x 2 factorial) as treatments to determine the effect of supplemental Arg on immune function and N retention. Infusion of LPS increased (LPS x h; P ≤ 0.01) rectal temperature, blood cortisol, tumor necrosis factor-alpha, IL-6, and haptoglobin. Steers infused with Arg had greater (P < 0.01) digested N, and tended (P = 0.09) to increase N retention regardless of LPS. In Exp 2, 4 steers were used to evaluate rumen-protected branched-chain AA (BCAA) bioavailability using a 4 x 4 Latin square design and supplementation with Ile, Leu, Val, or all three BCAA. Plasma Val on d 14 was highest when steers were supplemented with Val and lowest when steers were supplemented with BCAA, with steers supplemented with Leu and Ile being intermediate (trt; P = 0.01). Plasma Ile, Leu and Val increased from d 9 to d 14 (P ≤ 0.03). Supplementing rumen protected BCAA increased plasma BCAA, indicating bioavailability to the animal.;Two experiments (Exp 3 and 4) with randomized complete block designs evaluated supplemental BCAA on immune function and growth in a production setting. Treatments were no supplementation (CON) or 30 g/d of a 1:1:1 ratio of rumen-protected Ile, Leu and Val (BCAA). In experiment 3 there were 10 steers (ranch origin) per pen and 6 pens per treatment. In experiment there were 10 calves (from auction) per pen and 8 pens per treatment. In Exp. 3, IgG response, was greater (P = 0.02) for BCAA vs. CON steers. From d 15 to 28, DMI was less (P = 0.03), and ADG and G:F tended to be greater (P ≤ 0.11) for BCAA than CON. From d 29 to 56, ADG and G:F were greater (P < 0.05) for BCAA than CON. Overall G:F was greater (P = 0.05) for BCAA vs. CON. In Exp. 2, IgG response was less (P < 0.01) in BCAA vs. CON calves. From day 15 to 28, and from day 29 to 56, DMI was greater (P ≤ 0.05) for BCAA than CON calves. For the total feeding period, BCAA calves had greater (P = 0.05) DMI than CON calves. Differences observed between Exp. 3 and 4 could be due to age, source or diet composition as well, which could not be separated from age and source effects.