The Studies On The Application Of Arginine In Early-weaned Piglets

The thesis aims at evaluating the effects of dietary arginine supplementation on growth performance, intestinal function and immunity in early weaned piglets to offer the theoretical foundation for application of arginine in piglet nutrition.A total of 70 piglets (Landrace×Yordshire) weaned at 7 days of age were assigned randomly to one of 5 treatment groups (14 pigs/group), representing diets supplemented with 0.0,0.2,0.4,0.6 and 0.8% L-arginine, respectively. All diets were made isonitrogenous with addition of appropriate amounts of alanine at the expense of lactose and glucose. The experiment lasted 14 days. On days 7 and 14 after initiation of the supplementation,6 piglets from each group were randomly weighted and collected blood samples from the jugular vein for determining daily gain, blood biochemical indices and the concentrations of serum amino acids, hormones, immunoglobulins and cytokines, as well as lymphocyte proliferation; and slaughtered and sampled for determining organ index, intestinal morphology and related gene expression levels.The results showed that①dietary 0.6% and 0.8% arginine supplementation enhanced average daily weight gain and the serum concentrations of arginine, total protein, growth hormone and insulin while decreased the levels of blood ammonia and urea nitrogen.②dietary supplementation with arginine tended to improve the development of stomach, small intestine and villus, and remarkably increased the intestinal IL-2 gene expression levels on day 7; on day 14, the weight and length of small intestine were higher, and the villous height/crypt depth in jejunum and ileum had the tendency to be higher in piglets supplemented with 0.6%,0.8% arginine than those in control group.③spleen relative weight in piglets supplemented with 0.8% arginine on day 7 and thymus relative weight in piglets supplemented with 0.6% arginine were heavier than the control group; compared with control piglets, white blood cell and granulocytes numbers were higher in piglets supplemented with 0.8% arginine for 7 days while white blood cell and lymphocyte numbers were lower in piglets supplemented with 0.4% and 0.6% arginine on day 14; dietary supplementation with 0.6% and 0.8% arginine improved the serum IgM concentration, lymphocyte proliferation and the splenic expression level of IL-8 but decreased serum IL-8 concentration; on day 14, dietary arginine supplementation increased serum concentrations of IgG, IgM and TNF-a but decreased serum IL-8 concentration, and lymphocyte proliferation and the splenic expression level of IL-8 in piglets supplemented with 0.8% arginine were higher than those of other groups.Collectively, these findings indicate that arginine supplementation may improve the growth performance and the development of digestive tract, prevent intestinal villous atrophy, improve the development of immune organ and lymphocyte proliferation, and enhance both cellular and humoral immunity in early-weaned piglets. These results indicate that increasing L-arginine provision is beneficial for optimal immune responses in young pigs.