Effect Of γ-GABA On Growth,Immunity And Resistance To Ammonia-nitrogen Stress Of Cyprinus Carpio Var.jian

The present study was conducted to evaluate the effects of dietary γ-aminobutyric acid(GABA)supplementation on growth,immunity of Cyprinus carpio var.jian [initial average weight of(40.55±0.28)g].Six isoenergetic(17MJ/kg)and isonitrogen(32% CP)diets were formulated to contain 0(G0 group),30(G1 group),60(G2 group),90(G3 group),120(G4 group)and 150 mg/kg(G5 group)GABA equivalent/kg diet. After feeding for 8 weeks,the six treatment groups were subjected to ammonia-nitrogen stress(100 mg/L)for 24 h,the control group was set up at the same time. The results indicated that:(1)Average weight gain rate,specific growth rate in the groups supplemented with 30,60,90,120 and 150 mg/kg GABA were significantly higher than those in the G0 group(P<0.05). Feeding rate in the groups supplemented with 60,90,120 and 150mg/kg GABA were significantly higher than that in the G0 group(P<0.05). Feed efficiency and protein efficiency in the group supplemented with 90 mg/kg GABA were significantly higher than those in the G0 group(P<0.05),the other groups had no significant differences compared with the G0 group(P>0.05). Muscle crude protein content in the group supplemented with 90 mg/kg GABA was significantly higher than that in the G0 group(P<0.05),and the other groups had no significant differences compared with the G0 group(P>0.05).Compared with the G0 group,serum total protein(TP)of the group supplemented with 90 mg/kg GABA increased significantly(P<0.05);Serum albumin(ALB)of the groups supplemented with 60,90,120 and 150 mg/kg GABA increased significantly(P<0.05),and the group supplemented with 90 mg/kg GABA was the highest;Serum UREA of the groups supplemented with 30,60 and 90 mg/kg GABA decreased significantly(P<0.05);Serum glucose(GLUC)of the group supplemented with 120 mg/kg GABA increased significantly(P<0.05);Serum aspertate aminotransferase(AST)of the group supplemented with 90 mg/kg GABA decreased significantly(P<0.05);Serum alanine aminotransferase(ALT)levels of all the supplemented groups decreased significantly(P < 0.05).With the GABA supplementation increased,the superoxide dismutase(SOD)activity of the groups supplemented with 90,120 and150 mg/kg GABA were significantly higher than that in the G0 group(P<0.05),and no significant difference among three groups(P > 0.05).With the increase of the GABA supplementation,the malondialdehyde(MDA)content gradually reduced,the groups supplemented with 120 and150 mg/kg GABA were significantly lower than G0 group(P<0.05).Compared with the G0 group,LZM activity of the group supplemented with 60 and 90 mg/kg GABA were significantly increased(P<0.05);Head kidney NO content of all the supplemented groups were significantly increased(P<0.05),and the group supplemented with 60 mg/kg GABA was the highest;Spleen NO content of the groups supplemented with 90,120 and150 mg/kg GABA increased significantly higher(P<0.05),and the group supplemented with 90 mg/kg GABA was the highest.(2)Compared with control group,serum TP and ALB in the G0 group were significantly reduced(P<0.05);UREA,GLUC,AST and ALT levels increased significantly(P<0.05);Serum and liver SOD activity decreased significantly(P<0.05),MDA content,although there was a rising trend,but no significant difference(P<0.05);Head kidney LZM activity and NO content significantly increased(P<0.05),spleen LZM activity and NO content showed no significant difference(P<0.05);The head kidney,spleen and liver pancreas HSP90 m RNA relative expression all increased significantly(P<0.05).With the GABA supplementation increased, serum TP and ALB level gradually increased.Compared with the control group,the G1,G2,G3,G4 and G5 group serum TP showed no significant difference(P<0.05),G2,G3,G4 and G5 group showed significantly higher serum ALB than the G0 group(P<0.05),but the four groups were significantly lower than that of control group(P<0.05).With the GABA supplementation increased,GLUC decreased,there were no significant difference among the G3,G4 and the control group(P<0.05).Serum AST and ALT had a downward trend with the increase of GABA supplementation,but all the supplemented groups were significantly higher than that of control group(P<0.05).With the GABA supplementation increased,SOD had a marked increase in the serum and liver pancreas,there were no significant difference among the G2,G3,G4,G5 group and the control group(P<0.05).With the GABA supplementation increased,serum and liver MDA content had a downward trend,the G4 and G5 group were significantly lower than the control group(P<0.05).With the GABA supplementation increased,head kidney LZM gradually decline,there was no significant difference between the supplementation group and the control group(P<0.05).With the GABA supplementation increased,head kidney NO content decreased gradually,but the supplementation group were significantly higher than the control group(P<0.05).But spleen NO content increased gradually with the increase of the GABA supplementation,the G3,G4 and G5 group were significantly higher than the control group(P<0.05).With the GABA supplementation increased,head kidney,spleen and liver pancreas HSP90 m RNA relative expression were significantly higher than that of control group(P<0.05),the highest was the G3 group.Under the current conditions,it can concluded that: GABA can promote the growth performance, immunity and resistance to ammonia-nitrogen stress.There are significant difference of all GABA supplementation groups.On the premise of as far as possible to reduce the production cost,the suitable GABA adding level is 90 mg/kg.