Abstract:  This experiment was conducted to investigate the effects of Saccharomyces cerevisiae selenium and Clostridium butyricum on growth performance， antioxidant ability and intestinal microflora. One hundred and twenty 8\|day\|old broiler chickens were randomly divided into 4 groups with 3 replicates in each group and 10 chickens per replicate. The control group was fed the basal diet. The yeast selenium group was fed the basal diet supplemented with 025 mg·kg-1 Saccharomyces cerevisiae selenium. The Clostridium butyricum group was fed the basal diet supplemented with 01% Clostridium butyricum additive. The Se\|riched Clostridium butyricum group was fed the basal diet supplemented with 01% Clostridium butyricum additive and 025 mg·kg-1 Saccharomyces cerevisiae selenium. The experiment lasted for 35 days， growth， antioxidant ability and intestinal microflora of the chickens were determined. The results showed that the average daily weight gain in yeast selenium group， Clostridium butyricum group and Se\|riched Clostridium butyricum group were significantly higher than that of the control group （P<001）. The average daily weight gain of Se\|riched Clostridium butyricum group was significantly higher than that of the yeast selenium group （P<005）. Feed\|gain ratio of Se\|riched Clostridium butyricum group decreased by 446% compared with the control group （P<005）. The total antioxidant ability in serum of the yeast selenium group and Se\|riched Clostridium butyricum group increased by 1459% and 1305%， and the total superoxide dismutase in serum increased by 2235% and 2563% （P＞005），respectively. The content of malondialdehyde in serum of Se\|riched Clostridium butyricum group was significantly lower than that of the control group （P<001）. Clostridium butyricum could improve the number of Bifidobacterium spp. in jejunum and caecum （P<001） and decrease the number of Enterococcus spp. and E.coli in caecum of chickens （P<001）. The results indicated that the dietary supplementation of Saccharomyces cerevisiae selenium and Clostridium butyricum additive could improve the antioxidant ability in serum and the structure of intestinal microflora， the chickens in Se\|riched Clostridium butyricum group had better growth performance in comparison with those in the separate application groups.

Key words: Saccharomyces cerevisiae selenium, Clostridium butyricum, broiler, growth performance, antioxidant capacity, intestinal microflora