本试验旨在探讨饲粮中添加不同水平天蚕素抗菌肽对海兰褐仔公鸡小肠黏膜形态结构及免疫活性细胞数量的影响。选择336只1日龄健康海兰褐仔公鸡,随机分为7个处理,每个处理4个重复,每个重复12只鸡。7个处理分别为对照组(饲喂基础饲粮),抗生素组(150 mg/kg金霉素),抗菌肽Ⅰ(饲喂基础饲粮+150 mg/kg天蚕素抗菌肽)、Ⅱ(饲喂基础饲粮+200 mg/kg天蚕素抗菌肽)、Ⅲ(饲喂基础饲粮+250 mg/kg天蚕素抗菌肽)、Ⅳ(饲喂基础饲粮+300 mg/kg天蚕素抗菌肽)、Ⅴ组(饲喂基础饲粮+350 mg/kg天蚕素抗菌肽),饲养试验期为42 d。结果表明:各处理肠黏膜结构与对照组相比较完整,除十二指肠隐窝深度、空肠肌层厚度各处理之间无显著性差异(P>0.05)外,不同添加水平的抗菌肽组绒毛高度、黏膜厚度、肌层厚度均在一定程度上高于对照组,隐窝深度均在一定程度上低于对照组,抗菌肽Ⅴ组效果最为显著(P<0.05)。抗菌肽Ⅴ组空肠上皮内淋巴细胞数量显著高于对照组(P<0.05),抗菌肽Ⅲ、Ⅳ、Ⅴ组与对照组相比可显著提高十二指肠、空肠及回肠杯状细胞数量(P<0.05)。由此可见,饲粮添加天蚕素抗菌肽可显著改善海兰褐仔公鸡小肠黏膜上皮细胞形态,同时也增加了小肠免疫活性细胞的数量。其中抗菌肽Ⅴ组添加效果最好,天蚕素抗菌肽添加量为350 mg/kg。

This experiment is conducted to study the effects of dietary antimicrobial peptides (ABPs)—cecropin on small intestinal mucosal morphology and the number of immune active cells in Hy-Line Brown young roosters. Three hundred and thirty-six young roosters were selected, and randomly divided into seven treatments with four replicates in each treatment and twelve chicks in each replicate. The seven treatments were control group (fed a basal diet), antibiotics group (fed basal diet+150 mg/kg chlortetracycline), and 150, 200, 250, 300, 350 mg/kg ABPs groups (fed basal diet+cecropin), respectively. The feeding experiment lasted for 42 days. The results showed as follows: 1) the epithelial mucous membrane structure of duodenum, jejunum and ileum in ABPs group were integrated compared with that in control group. Except that there were no significant differences in crypt depth of duodenum and muscularis thickness of jejunum among all treatments (P>0.05), villus height, mucosal thickness and muscularis thickness in ABPs groups were higher than those in control group in a certain extent, crypt depth in ABPs groups was lower than that in control group in a certain extent, and ABPs group Ⅴ had the best effect, and was significantly higher than control group about above those indices (P<0.05). 2) The number of intraepithelial lymphocytes of jejunum in ABPs group Ⅴ was significantly higher than that in control group (P<0.05). 3) The number of goblet cells of duodenum, jejunum and ileum in ABPs groups Ⅲ, Ⅳ and Ⅴ was significantly increased compared with that in control group (P<0.05). In conclusion, adding different levels of cecropin to the diet can improve mucosal morphology of small intestine, and increase the number of immune active cells. Therefore, the optimal additive amount of cecropin is 350 mg/kg.