Arginine-genotype interactions and immune status.

The effects of arginine on selective immune responses were investigated in a high arginine-requiring (HA) and low arginine-requiring (LA) strain of chickens. Female chickens from these strains were fed diet containing a nutritionally inadequate level of arginine (0.53% arginine diet) or a surfeit level of arginine (1.53% arginine diet) for 2 weeks. Compared to LA chickens, HA chickens showed a higher feed efficiency, body weight gain, and relative thymus and spleen weights with L-arginine supplementation (p < 0.05). In both HA and LA chickens, a deficiency of arginine significantly decreased the delayed-type hypersensitivity response (p < 0.05) and nitric oxide (NO) production from macrophages. Chickens of the HA strain had higher NO production than those of LA strain with E. coli lipopolysaccharide (LPS) activation. This study indicates that dietary arginine concentration influences the immune status of chickens and that strains that differ in arginine requirements for growth may differ in their arginine needs for immune function.