Abstract: This experiment was conducted to study the effect of yeast concentrate on slaughter performance and carcass quality of Ross broilers.160 1-day-old Ross 308 broilers were selected and randomly assigned to 5 groups with 4 replicates in each group and 8 broilers in each replicate.Group Ⅰ was the control group which fed a basal diet.Groups Ⅱ to Ⅴ were fed the basal diet supplemented with 2000,4000,6000 and 8000 mg/kg yeast concentrate,respectively.Group Ⅱ was added yeast concentrate continously at the age of 1 to 42 days,groups Ⅲ to Ⅴ were added yeast concentrate continously at the age of 1 to 21 days,and 22 to 42 days was not added.The feeding experiment lasted for 42 days.The results showed that at the age of 21 days,compared with the control group,groups Ⅱ,Ⅲ,Ⅳ and Ⅴ had the tendency to increase the percentage of dressed weight,eviscerated yield,breast muscle yield and leg muscle yield,and decrease the percentage of abdominal fat,but the difference was not significant (P>0.05).Groups Ⅱ,Ⅲ and Ⅳ had significantly increased the a value of muscle and decreased the shear force of muscle (P<0.05),and the b value of group Ⅲ was significantly decreased (P<0.05).At the age of 42 days,compared with the control group,group Ⅳ had significantly reduced the percentage of abdominal fat and improved the percentage of breast muscle yield (P<0.05),groups Ⅱ,Ⅲ and Ⅳ had significantly increased the a value of muscle (P<0.05),gr oup Ⅱ had significantly decreased the shear force of muscle (P<0.05).In conclusion,the diets supplemented with yeast concentrate could significantly improve the slaughter performance and carcass quality of Ross broilers,and it also had the lag effect.The better level of yeast concentrate was 6000 mg/kg,the yeast concentrate was added at the age of 1 to 21 days,and 22 to 42 days was not added.

Key words: yeast concentrate; slaughter performance; carcass quality