Carryover effects of dietary L-arginine on the immune system in chickens

Chickens cannot biosynthesise arginine and many studies with other species have shown that immune responses can be influenced by dietary arginine. Additionally, as nutritional status in early life may permanently 'programme' immune functions in later life of humans and other species (Hales and Barker 1992), the present study investigated the carryover effect of short-term dietary arginine in early life on the immune system in chickens. Day-old ISA-Brown cockerels (n = 180) were allocated to 3 treatment groups, each with 6 replicates of 10 birds, and were given an arginine deficient basal diet (6.7 g arginine/kg) supplemented with 0 (control), 2.7 (LA) or 5.4 (HA) g L-arginine/kg for 4 weeks; then all birds were offered a commercial pullet grower feed (8.9 g arginine/kg) for another 8 weeks. The dietary arginine contents of the control, LA and HA diets were equivalent to 70, 100 and 130% respectively of NRC, USA, recommendations. Lymphoid organ weights, serum primary antibody levels against sheep red blood cells (SRBC) and bovine serum albumin (BSA), and cutaneous reactivity of toe-webs to phytohaemagglutinin (PHA)-M as an indicator of T cell responsiveness, were measured at 4 week intervals.