关键词: 地塞米松, 肉仔鸡, 小肽, 吸收, 小肠

Abstract: The study was conducted to investigate the effects of stress on the absorption of small peptides in the intestine of broilers. 200 21dayold male Arbor Acre broilers with similar body weight were randomly assigned into four groups and were injected subcutaneously in the abdomen with 1 mL dexamethasone (0, 0.1, 0.5 and 2.5 mg·kg1 BW) for 7 d. The body weight was measured 8 hours post the last injection on a fasting state, and the entire jejunum was collected. Histological study of jejunum was conducted, absorption of GlySar, content of plasma corticosterone, and expression of peptide transporter 1 mRNA of the broilers were analyzed. The results demonstrated that: (1)Dexamethasone reduced growth of the broilers (P<0.05)；(2) Dexamethasone inhibited absorption of GlySar by jejunum gut sacs and brush border membrane vesicles of the broilers (P<0.05);(3)Dexamethasone increased the crypt depth of the jejunum and decreased the villus height, absorption area and ratio of villus height to crypt depth (P<0.05). No significant effect on villus width was observed (P>0.05)；(4)Dexamethasone inhibited expression of peptide transporter 1 mRNA of the broilers (P<0.05). Based on this study, it could be concluded that stress inhibited the absorption of small peptides in broilers，the reasons may be related to the impairment of intestine mucosal morphology and the inhibition of expression of PepT1 mRNA.

Key words: dexamethasone, broilers, small peptides, absorption, small intestine