Abstract: Forty\|eight piglets (Duroc×Large white×Landrace) weaned at 21 days were used to study the effects of soybean antigen protein on the growth performance in a period of 15 days. The results showed that soybean antigen protein significantly decreased AFI by 25.88%(P<0.01)and increased diarrhea rate by 58.77% (P<0.01) compared with the control group. The serum D\|xylose detection indicated that the serum D-xylose concentration was decreased by 62.39%(P<0.01), 68.54%(P<0.01), 67.27%(P<0.01), 67.98% (P<0.01) and 6995%(P<0.01) after 1, 2, 3, 4 h and 5 h respectively compared with the control group. The lengths of the villi within the jejunum and ileum tissues of the test group significantly decreased by 27.56% and 22.43% (P<0.01) and the crypt depth significantly increased by 30.01% and 53.03% (P<0.01) compared with the control group. There was no significant difference between duodenal villi length and crypt length. The activity of NF-κB in jejunum were increased 71.87%(P<0.01). The results indicated that soybean antigen protein in diet exerted a negative influence on growth performance of weaning piglets. Soybean antigen protein could regulate the nuclear factor activity of intestinal mucosa tissue, and affect the morphology and structure of intestinal mucosa tissue, furthermore, affect feed intake, diarrhea rate and growth performance of weaning piglets．

Key words: weaning piglets, soybean antigen protein, growth performance, nuclear factor kappa-B