Abstract:An 8-week feeding trial was conducted to study the effect of dairy-yeast prebiotic (Grobiotic-A) on the survival rate, growth performance and antioxidant capacity of juvenile starry flounder Platichtahys stellatus. A total of 540 fish at body weight of 15.05±0.04 g were randomly allocated into six groups with three replicates and each replicate contained 30 fish. The fish were fed diets supplemented with 0, 0.4%, 0.8%, 1.2%, 1.6% and 2.0% dairy-yeast prebiotic, respectively. The results are shown as follows: 1) weight gain rate (WGR), specific growth rate (SGR), feed intake (FI), protein efficiency rate (PER) and condition factor (CF) increased whereas feed conversion ratio (FCR) decreased significantly (P<0.05) with the supplementation of dairy-yeast prebiotic in diets. However, there were no statistical differences in viscerosomatic index (VSI), hepatosomatic index (HSI) (P>0.05); 2) compared with the control, the activity of catalase (CAT) and total anti-oxidation capability (T-AOC) in serum and liver, and superoxide dismutase (SOD) and anti-superoxide anion activities (T-AOC) in serum were significantly increased (P<0.05), while the malondialdehyde (MDA) content in serum and liver of fish fed diets supplemented with dairy-yeast prebiotic was significantly decreased (P<0.05). These results indicated that dairy-yeast prebiotic positively influenced the growth performance and anti-oxidation of juvenile starry flounder in this experiment. Quadratic regression of SGR indicated that the optimal supplementation level of dairy-yeast prebiotic in juvenile starry flounder diet was 1.32%.
