Effects of dietary glutathione on growth performance, tissue biochemical indexes and non-specific immune related enzymes of GIFT Oreochromis niloticus

This study was conducted to investigate the effects of dietary glutathione(GSH)on growth performance,tissue biochemical indexes and non-specific immune related enzymes of GIFT Oreochromis niloticus.720 fish with initial weight of(3.27±0.04)g were randomly allocated into 6 groups.The fish in control group were fed the basal diet(G0),while those in the other five groups were fed the basal diet added with 80,160,240,320,400 mg/kg GSH.After 7 weeks' feeding,weight gain rate(WGR),specific growth rate(SGR),protein efficiency ratio(PER)and RNA/DNA ratio of liver in 320 mg/kg group were significantly higher than those in the control group(P0.05),and feed coefficient(FC)was significantly lower(P0.05).Hepatosomatic index(HSI)was higher in GSH added groups than the control,showing no significant difference(P0.05).Among all groups,no significant difference was found in condition factor(CF)(P0.05).The whole-body crude protein content and crude lipid content were significantly affected by dietary GSH levels(P0.05),while the ash and dry matter content showed no significant difference(P0.05).Serum UN content was significantly lower in 320 mg/kg group compared with the control(P0.05).The IGF-Ⅰlevel in G160-G400 mg/kg groups was significantly higher than the control and 80 mg/kg groups.The serum lysozyme(LZM)activities increased significantly in 240,320 and 400 mg/kg groups compared with the others(P0.05),and liver LZM activities were significantly higher in 320 and 400 mg/kg groups(P0.05).Dietary GSH increased serum alkaline phosphatase(AKP),phenoloxidase(PO)and liver AKP,acid phosphatase(ACP)activities,but no significant difference was shown(P0.05).Serum nitric oxide synthase(NOS)activities in 320 mg/kg group were significantly higher than the control(P0.05),but those in liver showed no significant difference(P0.05).The result suggested that dietary GSH could significantly improve growth performance,raise whole-body crude protein and crude lipid content,increase serum and liver IGF-Ⅰ level,and enhance activities of non-specific immune related enzymes in GIFT Oreochromis niloticus.The optimum level of dietary GSH was 355.13 mg/kg on the basis of WGR.