| This experiment was conducted to evaluate the effects of dietary glutathione(GSH)on growth performance,muscle quality,serum biochemical parameters,serum and liver antioxidant indices,liver and intestine immune indices of juvenile Japanese seabass.The contents and results are presented as follows:1 Influence of dietary glutathione on growth performace,muscle quality and serum antioxidant indices of Japanese seabass(Lateolabrax japonicus)The experiment was conducted to investigate the influence of dietary glutathione on growth performace,muscle quality and serum antioxidant indices of Japanese seabass.A total of 600 Japanese seabass with a mean body weight of(12.56±0.12)g were randomly divided into 6 groups with 4 replicates per group and 25 fishes per replicate,and fed a basal diet(G0)and 5 test diets supplemented with 100,300,400,500 and 700 mg/kg(G100,G300,G400,G500 andG700)glutathione,respectively.The feeding trial lasted for 56 days.The results showed that compared with the control group,the weight gain rates(WGR)in 400,500 and 700 mg/kg groups increased by6.2%,5.9%and 5.7%,respectively,but the difference was not significant(P>0.05).The feed coefficient(FC),protein efficiency rate(PER),hepatosomatic index(HIS),viscerosomatic index(VSI)and intestinesomatic index(ISI)had no significant differences among all groups(P>0.05).Dietary glutathione had no significant effects on the crude protein,crude lipid,ash and mosture contents of dorsal muscles among all groups(P>0.05).Compared with the control group,serum glucose(GLU)contents in100 and 700 mg/kg groups,usea nitrogen(UN)content in 100 mg/kg group,aspartate aminotransferase(AST)activity in 700 mg/kg group and alanine aminotransferase(ALT)activity in 500 and 700mg/kg group were significantly increased(P<0.05).The results showed that dietary glutathione had no significant effect on growth performance,muscle routine and serum biochemical parameters of Lateolabrax japonicus,but the weight gain rate had a gradual upward trend,which may be due to the different mechanisms of glutathione in Lateolabrax japonicus.2 Influence of dietary glutathione on antioxidant indices and resistance to nitrite exposure of Japanese seabass(Lateolabrax japonicus)The experiment was conducted to investigate the influence of dietary glutathione on antioxidant indices and resistance to nitrite exposure of Japanese seabass.After 56 d feeding trail,the serum and liver of Japanese seabass were sampled for antioxidant indices.And then,the nitrite exposure experiment was conducted.The results showed that the serum total antioxidant(T-AOC)in 400,500 and 700 mg/kg groups,serum glutathione content in 100,500 and 700 mg/kg groups,serum glutathione perxidase(GSH-Px)activity in 500,700 mg/kg groups and glutathione transferase(GST)activity in all test groups were significantly higher than that of control group(P<0.05).Compared with the control group,the superoxide dismutase((SOD)activity of liver in300,400 mg/kg groups and glutathione perxidase activity in 100,400,500 and 700mg/kg groups was significantly increased(P<0.05),the glutathione transferase activity of liver in 100 and 700 mg/kg groups was significantly decreased(P<0.05).There were no significant difference on catalase(CAT)activity,glutathione and malondialdehyde(MDA)contents and total antioxidant in the liver(P>0.05),but total antioxidant in 400mg/kg group was 31.7%higher than that of the control group.After 36,72 and 96 hours of nitrite exposure,the cumulative mortality of G100,G400,G500 and G700 groups was lower than that of the control group.The cumulative mortality of G400 group was significantly lower than that of the control group(P<0.05).After 96 hours of stress,the activity of CAT and the content of glutathione in the serum in G100 group were significantly lower than those of the control group(P<0.05),but there was no significant difference between the other groups and the control group(P>0.05).The activities of SOD and T-AOC in the serum of each experimental group were higher than those of the control group.The activity of SOD in the serum of G400,G500 and G700groups and T-AOC in the serum of G700 group were significantly higher than those of the control group.Serum MDA content and GSH-Px activity in all test groups were lower than those in the control group.Serum GST activity increased first and then decreased,but did not reach a significant level(P>0.05).After 96 hours of stress,the liver glutathione content of Japanese seabass in G300 and G500 groups decreased significantly(P<0.05).The activity of SOD in the liver of Japanese seabass in each test group were higher than taht in the control group.The activities of CAT and GSH-Px in the liver of Japanese seabass increased first and then decreased,but the difference was not significant(P>0.05).There were no significant differences in T-AOC,MDA content and GST activity in the liver of Japanese seabass among the experimental groups and the control group(P>0.05).The results showed that dietary glutathione could improve the antioxidant capacity of the serum and liver of Japanese seabass,enhance the resistance of juvenile Japanese seabass to nitrite exposure,and increase the antioxidant indexes of serum and liver during nitrite exposure.3 Influence of dietary glutathione on immune function and intestinal health of Japanese seabass(Lateolabrax japonicus)After the above feeding experiment,liver and intestinal tissues of juvenile Japanese seabass were sampled for the determination of liver immunity,intestinal immune and functional indexes and intestinal tissue structure.The results showed that the content of complement 3(C3)in the liver of Japanese seabass in the test groups was higher than that in the control group,but it did not reach a significant level(P>0.05).Lysozyme(LZM)content and complement 4(C4)content in G300,G400 and G500 groups were significantly higher than those in control group(P<0.05).There was no significant difference in the contents of interleukin-1beta(IL-1β)and tumor nerosis factor-α(TNF)in the liver between the test groups and the control group(P>0.05).The content of interleukin-6(IL-6)in liver of Japanese seabass in each test group was higher than that of control group,and the content of IL-6 in liver of Japanese seabass in G300 group was significantly higher than that of control group(P<0.05).There was no significant difference in intestinal ACP,AKP and total nitric oxide synthase(iNOS)(P>0.05)activities among the experimental groups.The intestinal LZM content of the test groups was higher than that of the control group,but did not reach the significant level(P>0.05).Na~+/K~+ATPase activity in whole intestinal tract of Japanese seabass in G700group was significantly higher than that in control group(P<0.05).There was no significant difference in intestinal gamma-glutaminotransferase(γ-GT)activity between the experimental groups and the control group,but the activity ofγ-GT in G700 group was significantly higher than that in G100 group(P<0.05).Compared with the control group,the foregut of Japanese seabass in each test group was uniformly and tightly arranged without obvious injury or abscission.The intestinal muscular layer thickness and fold height of bass in each test group were higher than those in the control group,but did not reach the significant level(P>0.05).The thickness of intestinal submucosa in G100 group and the width of intestinal wrinkle wall in G300,G400 and G500 groups were significantly higher than those in control group(P<0.05).The results indicate that adding glutathione to the diet can improve the liver immunity,intestinal immune and functional indexes of Japanese seabass,and improve the intestinal structure and digestive and absorptive capacity of Japanese seabass.However,glutathione also increased the indexes of inflammatory factors in the liver of Japanese seabass,which may affect the liver function of Japanese seabass. |
