Abstract: The objective of this study was to investigate the effects of dietary probiotics supplementation on growth performance and to ascertain the best additional level. A total of 750 one -day-old Cherry valley ducks were randomly allotted into 5 groups (the experimental groupⅠ,Ⅱ,Ⅲ,Ⅳ and the control group Ⅴ)with 3 replicates of 50 ducks each. Each group was fed the basal diet supplemented with 500,1000,1500,2000 and 0 mg/kg probiotics to 42 days of age, respectively. At the end of 14, 28 and 42 days of age, average body weight and feed to gain ration were calculated. Ducks fed diets supplemented with 1000 and 1500 mg/kg probiotics had significant higher(P<0.05)growth performance than those fed with the control group; diets supplemented with 1000 mg/kg probiotics had the best material meat rate; diets supplemented with 500 mg/kg probiotics was not significant than the control group; diets supplemented with 2000 mg/kg had higher(P>0.05)growth performance than those fed with 500 mg/kg and the control group. Dietary probiotics supplementation could increase body weight, reducematerial meat rate, then improve its growth performance, meat performance and economic efficiency, diets supplemented with 1000 mg/kg probiotics could get the best material meat rate and economic efficiency; diets supplemented with 1500 mg/kg probiotics could obtain the best meat performance; diets supplemented with 1000 mg/kg probiotics was the best additional level.

Key words: probiotics; Cherry valley duck; growth performance; meat performance; economic efficiencyt