【Abstract】 156 one-day-old broiler chicks were divided into control and treatment groups with 6 replicates for each group to determine the effects of xylanase supplementation(1‰)on performances and SS mRNA expression of broilers fed with wheat basal diet.The results showed that xylanase significantly increased ADG(average daily gain) by 4.81%(P<0.01),While decreased F/G(feed/gain)by 5.00%(P<0.05).Semi-quantitative RT-PCR results showed a significant down-regulation of SS mRNA expression in duodenum(16.45%,P<0.05),but not in jejunum of treated chicken.In addition,a clear difference in the abundance of SS mRNA expression was shown between duodenum and jejunum in the control chickens.This result indicates that the expression of SS mRNA is regulated differently in different segments of small intestine in the chicken and xylanase may affect the duodenal expression SS mRNA to achieve its growth promoting effects in broiler chickens fed on wheat basal diet.更多还原