Dietary Arginine Supplementation Enhances the Growth of Milk-Fed Young Pigs

This study was conducted to determine the effect of dietary arginine supplementation on the growth of artificially reared piglets. The pigs (n = 24; 7 d old) were removed from sows to a nursery facility and assigned randomly to 1 of the 3 treatments representing diets supplemented with 0, 0.2, or 0.4% L-arginine (on the basis of milk replacer powder). Each milk feeder was assigned to 1 dietary treatment. Fresh liquid milk replacer (18.6% dry matter) was provided daily ( approximately 0800 h) to piglets. Body weights of piglets were measured and jugular venous blood samples were obtained for metabolite analysis at d 7, 14, and 21 of age. Food intake did not differ between control and arginine-supplemented piglets [66.7 vs. 69.5 g dry matter/(kg body wt. d)]. Compared with control piglets, dietary supplementation with 0.2 and 0.4% L-arginine dose dependently increased (P < 0.05) plasma concentrations of arginine by 30 and 61%, and decreased (P < 0.05) plasma concentrations of ammonia by 20 and 35%, and those of urea by 19 and 33%, respectively. Dietary supplementation with 0.4% L-arginine also increased (P < 0.05) plasma concentrations of insulin and growth hormone by 24-27% in piglets, compared with controls. Between 7 and 21 d of age, the supplementation of 0.2 and 0.4% L-arginine to piglets enhanced (P < 0.05) average daily weight gain by 28 and 66%, and body weight by 15 and 32%, respectively, compared with control piglets. Collectively, both the metabolic and growth data demonstrate unequivocally that arginine is deficient in milk-fed young pigs and that this arginine deficiency represents a major obstacle to maximal growth in piglets.