The Effects Of Dietary Surfactin Supplementation On The Growth And Intestinal Health Of Gift Strain Of Nile Tilapia(Oreochromis Niloticus)

Two trials were conducted to study the effects of surfactin on the growth performance,the activities of digestive enzymes,serum biochemical indexes and intestinal health status of genetic improvement of farmed tilapia(GIFT)strain of nile tilapia(Oreochromis niloticus).1.Effects of different levels of surfactin on the growth performance,serum biochemical indexes,activities of digestive enzymes and intestinal health status of GIFT strain of nile tilapia(Oreochromis Niloticus)Three hundred and twenty GIFT with an average body weight of(12.01±0.03)g were randomly divided into 4 groups with 4 replicates per group and 20 fish per replicate.Fish were fed 4 experimental diets containing different levels of surfactin,which were 0(control group),50,100 and 200 mg/kg,respectively.The trial period was 49 days.Final body weight,weight gain rate,daily feed intake and specific growth rate were significantly increased(P<0.05),feed conversion ratio was significantly decreased by surfactin supplementation(P<0.05).There was no significant difference in feed rate among all treatment groups(P>0.05).The growth performance of 50 mg/kg supplementation group was higher than those of other supplementation groups.The activities of protease and lipase in intestinal tract were significantly increased by surfactin supplementation(P<0.05),there was no significant difference in amylase activity among all surfactin supplementation groups(P>0.05).The albumin level was significantly increased by surfactin supplementation(P<0.05).The activities of glutamicoxalacetic transaminease and glutamic-pyruvic transaminase,levels of total cholesterol,triglyceride(except 200mg/kg surfactin supplementation group)and low density lipoprotein cholesterol were significantly decreased by surfactin supplementation(P<0.05),the levels of high density lipoprotein cholesterol and the activities of lysozyme were significantly increased(P<0.05).The total antioxidant capacity level and the activities of glutathion peroxidase and superoxide dismutase(except 200 mg/kg surfactin supplementation group)were significantly increased(P<0.05),and the content of malondialdehyde was significantly decreased(P<0.05).The difference of activities of catalase was not significant among all treatment groups(P>0.05).The number of Escherichia coli was significantly decreased(P<0.05),and the number of Lactobacillus was significantly increased by surfactin supplementation(P<0.05).There was no significant difference in the total bacterial content among all treatment groups(P>0.05).The villus height was significantly increased(P<0.05),and the difference of muscular thickness was not significant among all treatment groups(P>0.05).It was concluded that surfactin could improve growth performance,serum biochemical indexes and intestinal tract health status of the GIFT.The recommended supplementation level of dietary surfactin was 50 mg/kg under present experimental condition.2.Effects of different types of surfactin supplemention on the growth performance,serum biochemical indexes,activities of digestive enzymes and intestinal health status of GIFT strain of nile tilapia(Oreochromis Niloticus)Two hundred and forty GIFT were randomly divided into four treatment groups with four replicates in each group and 15 fish in each replicate.The four treatment groups were control group(the basal diet),surfactin supplemention group ?(the basal diet+50 mg/kg surfactin),surfactin supplemention group П(the basal diet+ Bacillus subtilis fermentation product,the dietary surfactin level was 50 mg/kg)and flavomycin supplemention group(the basal diet+50 mg/kg flavomycin),respectively.The trial period was 49 days.Compared with control group,the final body weight,weight gain rate and specific growth rate of surfactin supplementation groups and flavomycin supplemention group were significantly increased(P<0.05),and the feed conversion ratio were significantly decreased by surfactin supplementation(P<0.05).The activities of protease lipase in intestinal tract of surfactin supplementation groups and flavomycin supplemention group were significantly increased(P<0.05),and the activitiy of lipase was significantly increased by surfactin supplementation(P<0.05).The difference of amylase activity was not significant among all treatment groups(P>0.05).The levels of immunoglobulin M and complement 3 and the activities of lysozyme in surfactin supplementation groups and flavomycin supplemention group were significantly increased(P<0.05),while the levels of blood urea nitrogen,total cholesterol,triglyceride and low density lipoprotein cholesterol were significantly decreased(P<0.05).The levels of high density lipoprotein cholesterol,the activities of glutamic-oxalacetic transaminease and glutamic-pyruvic transaminase were similar(P>0.05).The activities of superoxide dismutase and glutathion peroxidase and total antioxidant capacity level in intestinal tract of GIFT were significantly increased by surfactin or flavomycin supplementation(P<0.05).The levels of reactive oxygen species and malondialdehyde were significantly decreased(P<0.05).The catalase activities in all treatment groups were similar(P>0.05).The number of Escherichia coli was significantly decreased by surfactin or flavomycin supplementation(P<0.05),the number of Lactobacillus was significantly increased by surfactin supplementation(P<0.05).The total bacterial content was significantly decreased by flavomycin supplementation(P<0.05).The villus height was significantly increased by surfactin or flavomycin supplementation(P<0.05).It was concluded that different types of surfactin could improve growth performance,serum biochemical indexes and intestinal health status of the GIFT.In conclusion,surfactin supplementation in tilapia diet could improve growth performance,serum biochemical indexes and intestinal health status of the GIFT.The recommended surfactin supplementation level in tilapia diet was 50 mg/kg.