The Effects Of Dietary Probiotics On Growth,Nutritional Metabolism And Body Immunity Of The Grass Carp(Ctenopharyngodon Idellus)

This study was single factor expriment.We added Bacillus cereus,Bacillus subtilis,Paracoccus marcusii and Lacticacid bacteri at the dose of 1×10~9 CFU/kg to the basal diet of grass carp,respectively.The group which fed with basal diet(protein:38.85%;lipid:5.93%)was regarded as control group,and the experimental group were fed with probiotics diet.The effects of feeding probiotics on growth,nutritional metabolism and body immunity of the grass carp(Ctenopharyngodon idellus,4.39±0.01 g)was explored in this experiment.The experiment was implemented in the cage which the size was 1.5×1.5×1.5 m,and located in Che tian jiang reservoir.The grass carp were randomly distributed into 5 groups,each group had 3 replicates and each replicate had 40 fish,and 8 weeks was needed in this experiment.Compared with the control group,the growth of grass carp were promoted by four probiotics,and the specific growth rate of the probiotics groups was increased significantly(P<0.05).The weight gain rate of grass carp were significantly increased by adding P.marcusii,L.bacteria and B.subtilis probiotics(P<0.05),but the extent was not significantly increased after adding B.cereus(P>0.05).The hardness,gumminess,adhesiveness,chewiness,cohesiveness,and springiness of white meat were increased significantly by adding the probiotics(P<0.05).The activity of intestine amylase was significantly increased after adding B.subtilis,L.bacteria and B.cereus,while the activity of intestine lipase was significantly increased by L.bacteria and P.marcusii group(P<0.05).Four probiotics can significantly reduced the contents of serum glucose(P<0.05).The B.subtilis can significantly increased the contents of liver glycogen and the activity of hepaticlipase pyruvate kinase,hexokinase,and lactic dehydrogenase,and the activity of hepaticlipase lactic dehydrogenase was aslo significantly increased by L.bacteria and P.marcusii groups(P<0.05).B.subtilis was significantly increased the contents of serum high density lipoprotein cholesterol,whlie P.marcusii significantly reduced the contents of serum low density lipoprotein cholesterol(P<0.05).The contents of serum triglyceride was significantly reduced after adding B.cereus and P.marcusii,while the contents of serum total cholesterol was significantly reduced in P.marcusii group(P<0.05).The activity of hepatic lipase were significantly increased in the group of B.cereus,B.subtilis,and P.marcusii.However,those probiotics significantly reduced the contents of serum urea nitrogen and the activity of serum glutamic-pyruvic transaminase(P<0.05).Meanwhile,the activity of serum glutamic oxalacetic transaminase was significantly reduced by adding B.subtilis(P<0.05).The activity of hepatopancreas glutamic-pyruvic transaminase were significantly increased in the group of B.subtilis and L.bacteria(P<0.05).The levels of serum complement 3 of the experimental group were increased significantly,and the content of intestinal malonaldehyde was decreased,while the levels of serum complement 4 of B.cereus,B.subtilis,and L.bacteria group were increased significantly(P<0.05).The activity of serum alkaline phosphatase was significantly increased after adding B.subtilis and L.bacteria(P<0.05).The activity of intestinal glutathione peroxidase was significantly increased in B.subtilis,P.marcusii,and L.bacteria group,whlie the contents of intestinal glutathione was significantly increased in B.cereus,P.marcusii,and L.bacteria group(P<0.05).The group of B.subtilis and P.marcusii significantly up-regulated the expression level of CAT gene in intestinal,while the group of B.cereus and B.subtilis significantly up-regulated the expression level of Nrf2 and keap1 gene(P<0.05).The expression level of Mn-SOD and CuZn-SOD were significantly up-regulated in four probiotics and L.bacteria group(P<0.05),respectively.The expression level of TLR-8 and TNF-?gene were significantly down-regulated in four probiotics(P<0.05),and the expression level of MYD-88,IL-6 and TLR-4 were down-regulated in B.cereus,P.marcusii and L.bacteria group in intestine.The expression level of ZO-1,ZO-2,and ZO-3 gene were significantly up-regulated in the group of B.cereus,B.subtilis,and P.marcusii(P<0.05),respectively.The expression level of Claudin-12 was significantly up-regulated in the group of B.cereus(P<0.05).B.subtilis had the best effect on improving the level of glycometabolism and immunity,and L.bacteria had the best effect on improving the activity of digestive enzyme.P.marcusii had the best effect on improving the level of lipometabolism.In conclusion,probiotics can promote the growth of grass carp by improving the activity of digestive enzyme,and improving the level of nutrition metabolism and immunity,and B.subtilis had the best effect on promoting growth.