Effect Of Alginate Oligosaccharide On Replacement Of Fish Meal With Porcine Meat Meal In Diets Of Juvenile Golden Pompano(Trachinotus Ovatus)

Aiming to provide some scientific theories for the utilization of porcine meat meal(PMM)in feeds of golden pompano(Trachinotus ovatus),the effect of replacement of fish meal(FM)by PMM supplement with or without alginate oligosaccharide(AO)on growth and health of juvenile golden pompano were investigated in this study.1.Effect of replacement of FM with PMM on growth,antioxidant status,intestinal immunity and microflora of juvenile golden pompanoOn the purpose for investigating the effect of replacement of FM with PMM on growth and health status of juvenile golden pompano,golden pompano were fed with 6experimental diets(PC,P10,P20,P30,P40 and P50,in which FM were replaced by PMM with replacements of 0,10%,20%,30%,40% and 50%,respectively)for 56 days to analyze differences of growth performance,antioxidant status,gut microflora and expression of intestinal Nrf2 and Nf-κb signaling pathway between fish fed different diets.The results showed that the growth performance of fish were reduced and FCR were increased(P < 0.05)when 40% or 50% FM was replaced.Except for P10 group and P20 group,the antioxidant capacity in other groups were negatively affected(P < 0.05),and the expression of Nrf2 and antioxidant enzyme genes in other groups were downregulated in comparison to PC group(P < 0.05).Except for P10 group and P20 group,the expression of NF-κB and pro-inflammatory cytokine genes in other groups were upregulated,whereas expression of ant-inflammatory cytokine genes were down-regulated in comparison to PC group(P < 0.05).The intestinal morphology in both P40 group and P50 group were negatively changed in comparison to PC group(P < 0.05).Analysis of intestinal microbial flora showed that replacement of FM with PMM reduced the proportion of beneficial bacteria and increased proportion of pathogenic bacteria.In conclusion,substituting PMM for 30% of FM do not affect growth performance and FCR of fish,but negatively affect antioxidant capacity and immune response involved in Nrf2 and NF-κB signaling pathway.Regression analysis based on WGR and FCR expect that the optimal replacements are 25.68% and 23.96%,respectively.2.Effect of dietary AO on growth,antioxidant capacity and immune function of juvenile golden pompanoExperimental fish were fed with 3 experimental diets(which contained 0,0.7 g/kg and 6.0 g/kg AO,respectively)for 58 days to analyze differences of growth performance,antioxidant indexes,plasma indexes and expression of intestinal Nf-κb signaling pathway between fish fed different diets.In comparison to fish fed diet supplement without AO,the growth performance of fish fed diet supplement with 0.7 g/kg or 6.0 g/kg AO was improved and the FCR of fish fed diet supplement with 0.7 g/kg AO was reduced(P <0.05).The content of plasma glucose and triglyceride of fish fed diet supplement with 0.7g/kg AO was reduced and complement 3 content was improved in comparison to fish fed diet supplement without AO(P < 0.05).The complement 3 content and activities of alkaline phosphatase of fish fed diet supplement with 6.0 g/kg AO were improved in comparison to fish fed diet supplement without AO(P < 0.05).In comparison to fish fed diet supplement without AO,the antioxidant capacity and intestinal morphology of fish fed diet supplement with 0.7 g/kg or 6.0 g/kg AO was improved(P < 0.05).In comparison to fish fed diet supplement without AO,the expression of NF-κB and pro-inflammatory cytokine genes were down-regulated and anti-inflammatory cytokine gene was upregulated(P < 0.05).In conclusion,0.7 or 6.0 g/kg AO can improve growth and health status of golden pompano.Comparing the culture benefits,the more suitable level of AO is 0.7 g/kg.3.Effect of AO supplement on replacement of FM with PMM in diets of juvenile golden pompano On the basis of F0 diet(which contained 300 g/kg FM supplement without AO),other six experimental diet were formulated by adding 0.7 g/kg AO and subsequently replacing 0(A0),20%(A20),24%(A24),28%(A28),32%(A32)and 36%(A36)of FM with PMM,respectively.Fish were fed different diets for 56 days to investigate the effect of 0.7 g/kg AO on replacement of FM by PMM in diets of juvenile golden pompano.In comparison to fish fed diet supplement without AO(F0),the growth performance of fish fed diet supplement with 0.7 g/kg AO(A0)was improved and FCR was reduced(P < 0.05),and growth performance and FCR of fish fed A36 diet were not be negatively affected(P >0.05).In comparison to fish fed F0 diet,the antioxidant status of fish fed A0 diet and A36 diet were improved and content of plasma glucose,total protein and triglyceride were reduced(P < 0.05).In comparison to fish fed F0 diet,the activities of chymotrypsin and lipase of fish fed A0 diet were improved,whereas activities of alpha-amylase were reduced(P < 0.05);no negative change was observed between fish fed A36 diet and F0diet(P > 0.05).In comparison to fish fed F0 diet,the content of SCFAs of fish fed A0 diet and A36 diet were improved(P < 0.05).In comparison to fish fed F0 diet,the expression of IGF-I and II genes of fish fed A0 diet were up-regulated(P < 0.05).In conclusion,0.7 g/kg AO supplement can reduce the negative effect of replacement of FM by PMM on growth and health status of juvenile golden pompano.Through adding 0.7g/kg AO,36% of FM can be replaced with PMM.