Abstract: 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 distribution and quantity of IgA+-cell and IgA positive reaction substance in the gut were observed by immunohistochemistry. The results showed that the IgA+cell and IgA positive reaction substance were located in the tip of villus, lamina propria, surround intestinal gland, and lymphatic nodule of cecum. In two groups of high zinc-selenium and low zincselenium, the quantity of IgA+-cell and IgA positive reaction substances were decreased(P＜0.01), especially in the high zincselenium group. The distribution and the number of the IgA+-cell and IgA positive reaction substances were normal in the normal zinc-selenium group. This study indicated that the low zincselenium or high zinc-selenium would repress production of IgA, and 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.

Key words: zinc, selenium, IgA⁺-cell, broiler