| The concept of "eco-green and sustainable development" in aquaculture has greatly promoted the popularization of overhead price mixed feed.At present,artificial breeding of largemouth bass is limited by many factors.The use of overhead price mixed feed will cause slow growth and decreased appetite in the later period.,Liver and intestine health issues,seriously affecting the efficiency of breeding.How to solve the adverse effects of nutritional stress in aquaculture is a problem that we urgently need to solve.Yeast culture(YC),as a natural product produced by yeast fermentation,contains a variety of nutrients or functional components such as protein,polysaccharides,vitamins,amino acids,and nucleotides,which can increase the feed intake of farmed animals,enhance immunity,and resist disease The role of sex and regulation of the intestinal microbiota has received widespread attention.Therefore,two experiments were designed in this experiment,taking the largemouth bass as the research object,added yeast culture under high sugar and high cotton seed protein stress conditions,and explored the regulation of largemouth bass response nutrition by yeast culture in terms of growth performance,liver and intestine health,and intestinal flora.The mechanism of stress clarifies the protective effect of yeast culture on fish health,provides a theoretical basis for solving the current practical problems in largemouth bass farming and production,and expands new ideas for the wide application of yeast culture.1.The effect of yeast culture on the growth and health of largemouth bass under high starch stressThree experimental feeds with isonitrogen(CP47%)and lipid(EE12%)were prepared using tapioca starch as the starch source.They were the Control group(high starch feed with 15% starch level)and the HSY1 group(high-starch feed containing 3% yeast culture)and HSY3 group(high-starch feed containing 3% yeast culture)were fed largemouth bass with an initial body weight of 12.17±0.02 g for 8 weeks.The results showed that compared with the control group,feeding 3% yeast culture significantly increased the weight gain rate(WGR),specific growth rate(SGR),fullness(CF)and whole fish crude protein(CP)content of largemouth bass(P<0.05).From the perspective of liver health,the addition of yeast culture significantly improves the liver color of largemouth bass,reduces the vacuolation rate,liver-tobody ratio(HSI),liver fat and glycogen content,and increases liver glucokinase(GK)activity and its relative expression Reduce the activity of fructose-1,6-bisphosphatase(FBPase)and the relative expression of FBPase and glucose-6-phosphatase(G6Pase)genes(P<0.05).In addition,the addition of yeast culture significantly increased liver total superoxide dismutase(T-SOD)activity,up-regulated superoxide dismutase(SOD),catalase(CAT),glutathione peroxidase(GSH-Px)and anti-inflammatory factors(IL-10,TGF-β1)m RNA expression levels,while down-regulating the m RNA expression levels of pro-inflammatory factors(IL-8,IL-1β,TNFα)(P<0.05).Further analysis of the liver non-target metabolome,a total of 111 different metabolites were screened(5 were up-regulated and 106 were down-regulated),and 20 differential pathways were obtained,among which the liver lipid metabolism pathway changed significantly.From the perspective of intestinal health,the addition of yeast culture can significantly improve the degenerative changes of largemouth bass intestinal villi,short length,thin muscular layer,and few goblet cells after ingesting high starch feed,and up-regulate the intestinal barrier gene(The relative expression of ZO-1,Claudin,Occludin)and the reduction of diamine oxidase(DAO),endotoxin(Endotoxin)activity and D-lactate(D-lac)content in serum(P<0.05).The addition of yeast culture to high starch feed also significantly increased the relative expression of intestinal anti-inflammatory factors(IL-10,TGF-β1),and decreased the relative expression of pro-inflammatory factors(IL-8,IL-1β,TNFα)(P<0.05).In addition,yeast culture significantly increased the intestinal T-SOD,CAT and GSH-Px activities and the relative expression levels of their genes,and reduced the content of malondialdehyde(MDA)(P<0.05).Further studies on the intestinal flora found that the addition of 3% yeast culture significantly improved the structure of the intestinal flora of largemouth bass(OTUs,ACE index and Chao1 index)(P<0.05),and increased the intestinal Firmicutes and Pseudomonas The abundance of Bacillus phylum reduces the abundance of Proteobacteria.Bugbase predicts that adding 3% yeast culture to high starch feed significantly increases the relative abundance of probiotics(such as lactic acid bacteria,bacillus and bifidobacteria)and reduces the relative abundance of potential pathogenic bacteria(Plesiomonas)(P<0.05)).It can be seen that adding appropriate yeast culture to feed can improve or alleviate the adverse effects of high starch on the liver and intestine health of largemouth bass,thereby improving its growth performance.2.Study on the effect of yeast culture on the growth and health of largemouth bass under the stress of high cotton seed proteinFour kinds of experimental feeds with isonitrogen(CP48%)and fat(EE12%)were prepared,which were basic feed(FM,control group),high cotton seed protein feed(CPC,concentrated cottonseed protein instead of 36% fish meal in basic feed),and added 1% yeast culture feed(CPCY1,CPC+1% yeast culture)and 3% yeast culture feed(CPCY3,CPC+3% yeast culture),fed with largemouth bass with an initial body weight of 12.17±0.02 g 8 weeks.The results show that,Compared with the CPC group,feeding 3% yeast culture significantly improved the weight gain rate(WGR),specific growth rate(SGR),protein efficiency(PER),feeding rate(FR)and fatness(CF)of largemouth bass And the crude fat(EE)content of whole fish(P<0.05).From the perspective of liver health,the addition of yeast culture can significantly improve liver color,reduce vacuolation rate,liver-to-body ratio(HSI),liver fat and glycogen content,and increase liver phosphofructokinase(PFK)and glucokinase(GK)activities And its relative expression level,reduced fructose-1,6-bisphosphatase(FBPase)activity and the relative expression level of G6 Pase gene(P<0.05).In addition,the addition of yeast culture also significantly increased the activity of liver T-SOD,CAT,GSH-Px and the relative expression levels of its genes and anti-inflammatory factor IL-10,and down-regulated pro-inflammatory factors(IL-8,IL-1β,TNFα)The relative expression level of(P<0.05).From the perspective of intestinal health,the addition of yeast culture can significantly improve the degenerative changes of largemouth bass intestinal villi,thin muscular layer,and few goblet cells after ingesting high cotton seed protein feed,and up-regulate the relative expression of intestinal barrier genes(ZO-1,Claudin,Occludin)and reducing the activity of diamine oxidase(DAO)and the content of D-lactate(D-lac)in serum(P<0.05).The addition of yeast culture to the high cotton seed protein feed also significantly increased the relative expression of intestinal anti-inflammatory factors(IL-10,TGF-β1),and decreased the relative expression of pro-inflammatory factors(IL-8,IL-1β)(P <0.05).In addition,yeast culture significantly increased the intestinal T-SOD,CAT,GSH-Px activity and relative gene expression,and reduced MDA content(P<0.05).Further investigation of the intestinal flora found that the addition of 3% yeast culture significantly improved the structure of the largemouth bass intestinal flora(OTUs,ACE index and Chao1 index)(P<0.05),and increased the phylum Firmicutes and Bacteroides Abundance,reduce the abundance of Proteobacteria.Bugbase predicts that adding 3% yeast culture to high starch feed significantly increases the relative abundance of probiotics(Lactobacillus)and reduces the relative abundance of potential pathogenic bacteria(Vibrio,Brevimonas)(P<0.05).It can be seen that adding appropriate yeast culture to feed can improve or alleviate the adverse effects of excessive concentrated cottonseed protein on the liver and intestine health of largemouth bass,thereby improving its growth performance. |
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