日粮锌、硒水平对肉鸡肠道黏膜屏障结构的影响

为了探讨微量元素锌和硒相互作用对肉鸡肠道黏膜屏障结构的影响，将24只1日龄AA肉鸡随机分3组，分别饲喂添加有高锌高硒(锌1000mg／kg、硒5mg／kg)、低锌低硒(锌34mg／kg、硒0．08mg／kg)或常锌常硒(锌50mg／kg、硒0．15mg／kg)的日粮45d后，观察肠黏膜上皮细胞、上皮内淋巴细胞和盲肠扁桃体的形态结构变化。结果表明：高锌高硒或低锌低硒组肉鸡的肠黏膜结构有明显的损伤，表现为肠黏膜上皮细胞萎缩，绒毛长度下降，上皮内淋巴细胞数量减少；盲肠扁桃体的弥散淋巴组织和淋巴小结中，淋巴细胞数量减少，细胞出现肿胀，有的核消失，结缔组织增生，淋巴小结萎缩。尤其是高锌高硒组的损伤最为严重。而常锌常硒组肉鸡肠黏膜和盲肠扁桃体的形态结构正常。结论：日粮中按锌50mg／kg、硒0．15mg／kg的比例添加，对于维持肠道黏膜的正常屏障结构是合适的。过高或过低的锌和硒对小肠黏膜有毒性作用，破坏其屏障功能；而且高锌和高硒可相互促进以增强其毒性作用。

Effect of Different Zinc and Selenium Level in Diet on the Gut Barrier Function in the Broiler

To explore the effect of trace elements zinc, selenium and their interaction on the gut barrier function in the broiler, twenty-four one-day-old AA broilers were divided into three groups, and were fed with the different diets including high zinc-selenium (Zn 1 000 mg/kg, Se 5 mg/kg),low zinc-selenium (Zn 34 mg/kg, Se 0.08 mg/kg), and normal zinc-selenium (Zn 50 mg/kg,Se 0.15 mg/kg), respectively. After forty-five days, the broilers were killed and the structure of mucous epithelium in the small intestine and cecal tonsil was observed. The results showed that in the two groups of high zinc-selenium and low zinc-selenium, the length of intestinal villus and number of intraepithelial lymphocyte decreased. Their epithelium of mucasa was atrophy and defluxion, especially in the high zinc-selenium group.The necrosis and depletion of lymphocytes and proliferation of connective tissue were observed in the cecal tonsil. But the structures of mucous epithelium and cecal tonsil were normal in the normal zinc-selenium group. This study indicated that the supplementary level of selenium at 0.15 mg/kg and zinc at 50 mg/kg in diet should be an appropriate ratio which would keep the normal gut barrier function in the broiler.