Effects Of Marine Animal Protein Hydrolysates Supplementation In Low Fish Meal Diets On Growth,Feed Utilization And Antioxidant Capacity Of Juvenile Grouper(Epinephelus Fuscoguttatus?×Epinephelus Lanceolatus?)

The research includes the following two parts:(1)the hybrid grouper(Epinephelus fuscoguttatus ? × Epinephelus lanceolatus ?)with an initial weight of about 9.6g was used to explore the effects of marine animal protein hydrolysates(fish soluble,shrimp paste,squid paste or their mixture)inclusion in low fish meal basis diet on the growth,nutrient utilization,body composition and antioxidant capacity.Results showed that the three marine animal hydrolyzed proteins,especially stickwaters,can significantly improve the nutritional value of low fish meal diet,and meanwhile,the growth of grouper was partly related to the content of taurine.(2)On the basis of experiment(1),another study was conducted to further reduce the application of fish meal in the diet of hybrid grouper with the inclusion of fish soluble,and the results show that the fish soluble inclusion can effectively replace 40% of fish meal without negative effects on the growth performance.Experiment 1: The present study was used to investigate the role of marine animal protein hydrolysates inclusion on the growth,feed utilization and antioxidant capacity of hybrid grouper.The diet with 60% and 40% fish meal were considered as positive control(PC)and negative control(NC),respectively.Another five diets were formulated with the supplementation of crystal amino acid(CAA),fish soluble(FS),shrimp paste(SP),squid paste(SUP)or their mixture(MIX).Triplicate groups of fish were fed the experimental diets for 80 days.Results showed that the specific growth rate of grouper was significantly reduced in the NC and CAA groups compared to the PC group.However,the supplementation of marine animal protein hydrolysates significantly improved the negative effect on SGR induced by high fishmeal replacement.Meanwhile,the optimal dietary taurine was estimated to be 0.31% based on the regression of SGR and taurine.The fish in the NC group obtained the lowest feed intake(FI),while no significant difference was observed in other treatments.The feed efficiency rate(FER)and protein efficiency rate(PER)followed the similar pattern with that of FI.The NC group obtained significantly lower MDA content than other treatments,and meanwhile,no significant difference was observed in all treatments except the NC group.The activity of SOD in fish fed the diet with mixed hydrolysates were significantly higher than that of CAA group,while no significant difference was observed in the remaining groups.Meanwhile,the NC and CAA groups obtained significantly lower CAT activity than other treatments.In above,the inclusion of marine animal protein hydrolysates,especially the fish soluble,significantly improved the nutritional value of the low fish meal diets.Experiment 2: The study was conducted to explore the further replacement of fish meal by plant protein with the supplementation of fish soluble.The diet with 50% fish meal was considered as the control,and mixed plant protein were used to replace 30%(30FM)and 40% fish meal(40FM)with or without the supplementation of fish soluble.The crystal amino acid(lysine and methionine)and taurine were also supplemented to make it consistent in all treatments.Triplicate groups of grouper with initial weigh of about 10.55 g were fed the experimental diets for 11 weeks.Results showed that the specific growth rate of grouper was significantly reduced in the 30 FM group compared to the control.However,the supplementation of fish soluble significantly improved the negative effect on SGR induced by high fishmeal replacement.The fish in 30% fishmeal replacement group obtained the lowest feed intake(FI),which was significantly lower than other treatments,while no significant difference was observed in other treatments.The feed efficiency rate(FER)of grouper was significantly reduced in the 30 FM groups compared to the control.However,the supplementation of fish soluble significantly improved the deceased FER induced by high fishmeal replacement.The protein efficiency rate(PER)and protein retention rate(PRR)followed the similar pattern with that of FER.The 40% fishmeal replacement with supplementation of fish soluble obtained significantly lower CAT content than the control group,while the replacement of fishmeal did not produce any significant difference on the MDA content and SOD activity.In conclusion,40% fish meal could be replaced with the inclusion of fish soluble without negative effect on growth and antioxidant capacity.