Effects of glutamine on lymphocyte proliferation and intestinal mucosal immune response in heat-stressed broilers

Abstract

To investigate the protective effect of glutamine (Gln) on lymphocyte proliferation and the intestinal mucosal immune response in heat-stressed broilers, 360 21-day-old Arbor Acres (AA) broilers were assigned to 4 groups in a completely randomized design, each of which included 6 replicates with 15 birds per replicate for 21 days. The chickens were fed a basal diet under no stress (NS group), a basal diet under heat stress (HT group), or a basal diet under heat stress with the addition of either 0.5 % or 1.0 % Gln. The results showed that the broilers in the HT group exhibited fewer proliferating peripheral lymphocytes, a lower growth performance, phagocytic rate and index of neutrophils, fewer goblet cells in whole intestine and intraepithelial lymphocyte (IEL) cells in the ileum, a lower sIgA content in the duodenum and the jejunum, a lower immunoglobulin content of serum and intestinal mucosa, than those of the NS group (p<0.05). Diets supplemented with Gln increased growth performance, the number of proliferating peripheral lymphocytes, the phagocytic rate and phagocytic index of neutrophils, the number of whole intestine goblet cells and ileum IEL cells, the sIgA contents of the duodenum and the jejunum, and the immunoglobulin contents of serum and intestinal mucosa (p<0.05) in broilers exposed to HT. In conclusion, Gln can enhance intestinal immune function in broiler chickens by stimulating T and B lymphocyte proliferation, increasing the number of goblet cells and IEL cells, as well as increasing the content of sIgA and immunoglobulin secretion.