Effects Of Inulin In High-Fat Feed On Common Carp Growth,Antioxidant And Lipid Metabolism

In fish feed,proper increase of fat content can save feed protein and reduce feed cost.However,excessive fat intake by fish can easily cause fat deposition and metabolic disorders,resulting in related diseases and economic losses.Inulin is a fructan-type plant polysaccharide with the functions of promoting growth of aquatic animals,improving immunity,promoting lipid metabolism,anti-oxidation and improving intestinal health.Common carp(Cyprinus carpio)is one of the major freshwater economic fish in China.In the process of culture,the phenomenon of excessive fat deposition in the body is becoming more and more serious.The purpose of this study was to explore the effects of Inulin on the growth,antioxidant capacity and lipid metabolism of common carp.In this experiment,common carp were used as the research object,and the experiment was divided into 6 groups: basic diet CK group(crude fat,80.00g/kg),high fat diet G0 group(crude fat,120.00 g/kg),high fat diet G1 group(5.00 g/kg),G2group(10.00 g/kg),G3 group(15.00 g/kg)and G4 group(20.00 g/kg),for an 8-week feeding experiment.After the feeding experiment,biochemical,immunological,histological and molecular biology techniques were used to study the effects of adding Inulin to high-fat diets on the growth performance,digestion and metabolism,immune function,antioxidant capacity and hepatopancreas and intestinal tissues of common carp.The results show that:1.Effects of Inulin added to high-fat diet on growth performance and muscle nutritional composition in common carpCompared with CK group,Final weight(FW),Weight gain rate(WGR),Specific growth rate(SGR),Feed conversion ratio(FER)and Protein efficiency ratio(PER)in G0 and G1 groups were significantly decreased(P<0.05),while FW,WGR,SGR,FER and PER in G2,G3 and G4 groups were significantly increased compared with G0 group(P<0.05).Through linear regression analysis,the highest SGR was achieved with the addition of Inulin at 15.23 g/kg in the high-fat diet.Compared with CK group,the muscle crude fat content was significantly increased in G0 group(P<0.05),while the muscle crude fat content in G3 group was significantly decreased than G0 group(P<0.05).2.Effects of Inulin added to high-fat diet on the activities of digestive enzymes and protein metabolic enzymes in common carpCompared with CK group,hepatopancreas,proximal intestine(PI),mid intestine(MI)and distal intestine(DI)Lypase(LPS)activity in G0 and G1 groups was significantly decreased(P<0.05),and hepatopancreas,PI,MI and DI LPS activity in G3 group was significantly increased than G0 group(P<0.05).Compared with CK group,the activities of serum Alanine aminotransferase(GPT)and Aspartate aminotransferase(GOT)in G0 and G1 groups were significantly increased(P<0.05),while the activities of GPT and GOT in hepatopancreas were significantly decreased(P<0.05).Compared with G0 group,the activities of serum GPT and GOT in G2,G3 and G4 groups were significantly decreased(P<0.05),while3.Effects of Inulin added to high-fat diet on lipid metabolic enzyme activity and related gene expression in common carpCompared with CK group,serum Triglyceride(TG)and Total cholesterol(T-CHO)contents and the activities of Acetyl Co A carboxylase(ACC)and Fatty acid synthase(FAS)in hepatopancreas and muscles in G0,G1 and G2 groups were significantly increased(P<0.05).While the activities of Hormone-sensitive triglyceride lipase(HSL),Adipose triglyceride lipase(ATGL)and Carnitine palmitoyltransferase-1(CPT-1)in hepatopancreas and muscles in G0 and G1 groups were significantly decreased(P<0.05).Compared with G0 group,serum TG and TCHO contents and hepatopancreas and muscle ACC and FAS activities in G2,G3 and G4 groups were significantly decreased(P<0.05).While hepatopancreas and muscle HSL and ATGL activities in G2,G3 and G4 groups were significantly increased(P<0.05).Compared with CK group,the m RNA expression of hepatopancreas and muscle ACC-1,FAS and LPL,and hepatopancreas peroxisome proliferator activated receptorβ(PPARβ),PPARγand Srebp was significantly increased in G0 group(P<0.05);the m RNA expression of hepatopancreas ATGL,and muscle CPT-1 and HSL were significantly decreased(P<0.05).Compared with G0 group,hepatopancreas PPARβ,Srebp-1 and ACC-1 in G1,G2,G3 and G4 groups,hepatopancreas and muscle FAS and LPL m RNA expression in G3 and G4 groups were significantly decreased(P<0.05);hepatopancreas ATGL,CPT-1,HSL and PPARα in G3 group was significantly increased(P<0.05).4.Effects of Inulin added to high-fat diet on the immune index in common carpCompared with CK group,serum Lysozyme(LZM)and Alkaline phosphatase(AKP)activities in G1 and G2 groups,and Complement 3(C3),Complement 4(C4)and Immunoglobulin M(Ig M)contents in G0,G1 and G2 groups were significantly decreased(P<0.05).Compared with G0 group,serum LZM and AKP activities in G2,G3 and G4 groups,and C3,C4 and Ig M contents in G3 and G4 groups were significantly increased(P<0.05).5.Effects of Inulin added to high-fat diet on antioxidant ability in common carpCompared with CK group,hepatopancreas,PI,MI and DI Malondialdehyde(MDA)content in G0 and G1 groups was significantly increased(P<0.05);Total antioxidant capacity(TAOC)of hepatopancreas and DI and Glutathione(GSH)content in hepatopancreas,PI,MI and DI in G0 and G1 groups,Total superoxide dismutase(T-SOD)activity of hepatopancreas,PI,MI and DI and Glutathione peroxidase(FGSH-Px)activity of hepatopancreas,MI and DI,and Catalase(CAT)activity of DI in G0,G1 and G2 groups were significantly decreased(P<0.05).Compared with G0 group,MDA content of hepatopancreas,PI,MI and DI in G3 and G4 groups was significantly decreased(P<0.05);hepatopancreas and DI T-AOC in G3 group,hepatopancreas,PI,MI and DI GSH content and T-SOD activity in G3 and G4 groups,hepatopancreas,MI and DI GSH-Px activity and hepatopancreas and DI CAT activity in G3 and G4 groups were significantly increased(P<0.05).6.Effects of Inulin added to high-fat diet on histomorphology of intestine and hepatopancreas in common carpCompared with CK group,folds height of PI,MI and DI,muscle layers thickness of PI and MI in G0 and G1 groups,and folds width of MI and DI were significantly decreased(P<0.05).Compared with G0 group,folds height of PI,MI and DI in G2,G3 and G4 groups,and folds width of PI,MI and DI in G3 group were significantly increased(P<0.05).Compared with CK group,intestinal mucosal damage and atrophy of MI and DI were observed in G0 and G1 groups.Compared with the G0 group,the morphological structure of intestinal mucosal folds in G3 and G4 groups was intact and the folds were well developed.Compared with CK group,a large number of lipid vacuoles of hepatopancreas were observed in G0 and G1 groups,some nuclei dissolved or disappeared,and the cell borders were blurred.Compared with G0 group,the hepatopancreas in G3 and G4 groups had regular cell morphology and complete tissue structure.In summary,considering economic factors,Under the conditions of this test,the appropriate amount of Inulin in high-fat diet of common carp is 15.00 g/kg.