Dietary L-arginine level alters plasma nitric oxide and apha-1 acid glycoprotein concentrations, and splenocyte proliferation in male broiler chickens following Escherichia coli lipopolysaccharide injection

Experiments were conducted to determine the effect of dietary arginine (Arg) on nitric oxide (NO) production following injection with Escherichia coli lipopolysaccharide (LPS) and splenocyte proliferative response to concanavalin A in broilers. Birds were fed experimental diets containing Arg at levels of 6.5, 14.4 or 24.4 g/kg diet in experiment 1, and 6.5, 14.4 or 19.3 g/kg diet in experiment 2, respectively, for 7 days and were then intraperitoneally injected with LPS (2 mg/kg body weight) after 16 h fasting. Maximum NO production estimated by plasma nitrite concentration was observed 6 or 10 h after LPS injection in all Arg groups. Dietary Arg level and/or intake were positively associated with NO production. NO production at 6 or 10 h after LPS injection coincided with changes in plasma alpha-1 acid glycoprotein concentration, an acute phase substance, at 10 or 24 h post-LPS injection. Splenocyte proliferation in chicks fed on Arg-sufficient (14.4 g/kg) diet was greater that that in chicks fed Arg-deficient or -excess diets. The results suggest that dietary Arg level and/or intake proportionally affect NO production, and acute phase inflammatory responses following LPS injection, and that marginal deficiency or excess of dietary Arg might reduce splenocyte proliferative responses.