Effects Of Dietary Supplementation With Plant Extracts On Largemouth Bass At Different Carbohydrate Levels

Largemouth bass is an important economically farmed fish in China and is favoured by the public for its tasty meat.However,as a carnivorous fish,its ability to utilise carbohydrates is low.And the research on the regulation of glucose metabolism in fish by medicinal plants has become a hot spot in the industry in recent years,often appearing as feed additives in commercial feeds.In this experiment,two plant additives were selected from juvenile Largemouth bass with an initial mass of 7.50±0.23 g to study the effects of HEALTHLIVER(a complex additive with mulberry leaf flavonoids and tannins as the main components)and fenugreek extract on the growth performance,biochemical parameters and metabolism of Largemouth bass at different carbohydrate levels.This experiment explored the effects on carnivorous fish from the perspective of plant extracts,which provided a theoretical basis for subsequent studies on the application of plant extracts in carnivorous fish feeds.Study 1: Effects of adding HEALTHLIVER in feed on largemouth bassThe basal feed was prepared with 10% α-starch as the main sugar source,supplemented by protein and fat sources,and 0,1500 mg/kg and 3000 mg/kg HEALTHLIVER were added to the basal feed to produce three same nitrogen,same energy test feeds(S1,S2 and S3).A total of 225 fish were randomly assigned to 9breeding boxes,and each feed was set up in 3 parallel groups.The breeding experiment lasted for 8 weeks.To investigate the effect of HEALTHLIVER on largemouth bass.The results of the study are as follows:1.Effects of HEALTHLIVER on growth performance,body composition and biochemical indexes of largemouth bassHEALTHLIVER significantly increased the WGR and survival rate of largemouth bass,and decreased the FCR(P<0.05),but had no significant effect on SGR.HEALTHLIVER had no significant effect on the body composition of the three groups of test fish(P>0.05).The biochemical indexes of TP,TC,TG,LDL and ALB in the plasma of largemouth bass were significantly increased with the addition of HEALTHLIVER(P<0.05),GLU levels,ALT and AST levels were not statistically different(P>0.05).The liver SOD and CAT activities of largemouth bass were significantly decreased with the addition of glycosides(P<0.05).In the 3000 mg/kg group,the liver MDA content of largemouth bass Significantly lower(P<0.05).2.Effects of HEALTHLIVER on Antioxidation and Glycolipid Metabolism of Largemouth BassThe liver antioxidant status of largemouth bass was studied by hepatic IL-10,IL-1β and TNF-α.IL-10 and IL-1β in 1500mg/kg HEALTHLIVER addition group were significantly up-regulated,while 3000mg/kg HEALTHLIVER addition group TNF-αwas significantly down-regulated(P<0.05).PPARα,FAS,GK,HK,G6 PDH,PK,G6 Pase and PEPCK to study glycolipid metabolism in largemouth bass.The expressions of PPARα,FAS,PK,G6 Pase and PEPCK were significantly increased with the addition of HEALTHLIVER(P<0.05).The expressions of GK,HK and G6 PDH were significantly up-regulated in the 1500 mg/kg HEALTHLIVER group(P<0.05).3.ConclusionThe addition of HEALTHLIVER to the feed can significantly improve the survival rate,growth performance and feed utilization of largemouth bass,and has a certain alleviation effect on liver oxidative stress.HEALTHLIVER regulates the pentose phosphate pathway in largemouth bass and promotes the expression of glycolysisrelated genes,thereby reducing the hepatic glucose stress in largemouth bass.Study 2: Effects of feed supplementation with fenugreek extract on largemouth bass at high carbohydrate levelsThe basal feed was formulated with 20% α-starch as sugar source,protein source and fat source added,and 0 and 1000 mg/kg fenugreek extract was added to the basal feed to produce two same nitrogen,same energy test feeds(HC and HF).A total of 150 fish were randomly assigned to 6 breeding boxes,each feed was set up in 3 parallel groups,and the breeding experiment lasted for 8 weeks.To investigate the effect of fenugreek extract on largemouth bass at high carbohydrate levels.The results of the study are as follows:1.Effects of Fenugreek extract on growth performance,body composition and biochemical indices of largemouth bass at high carbohydrate levelFenugreek extracts had no significant effects on WGR,SGR,FCR,survival rate and body composition of largemouth bass(P >0.05).Fenugreek extract significantly decreased the level of CAT in liver,and significantly increased the level of MDA in liver of largemouth bass(P <0.05);There were no significant effects on plasma TP,TC,TG,LDL,HDL,ALB,ALT,AST,GLU,liver SOD and liver glycogen content.2.Effects of fenugreek extracts on liver and serum of largemouth bass under highcarbohydrate conditions based on metabolomic analysisA total of 5 up-regulated differential metabolites and 2 down-regulated differential metabolites were screened in the liver metabolome(P<0.05),mainly enriched in monocyclic lactam biosynthesis,lysine biosynthesis,cysteine and methionine acid metabolism pathway.A total of 6 up-regulated differential metabolites and 29 downregulated differential metabolites were screened in the serum metabolome(P<0.05),mainly enriched in choline metabolism,glycerophospholipid metabolism,arginine and proline metabolism,and protein in cancer in digestion and absorption.3.ConclusionUnder high-carbohydrate conditions,fenugreek extract aggravated hepatic oxidative stress in largemouth bass without significant improvement in growth,body composition and plasma biochemical parameters.Metabolomics results showed that fenugreek extract had a greater impact on glycerophospholipid metabolism and amino acid-related metabolic pathways,and reduced the production of various functional amino acids and phosphatidylcholine in serum and liver.