Fermented Feed On Growth Performance,Antioxidant Capacity And Intestinal Microorganisms Of Macrobrachium Nipponense

With the rapid development of aquaculture industry,traditional feed cannot adapt to modern aquaculture level gradually.In recent years,the price of fish meal and soybean meal is increasing,and the breeding cost is increasing.Meanwhile,to solve the problem of disease,farmers use a lot of antibiotics,which not only pollute the breeding environment,but also lead to bacterial resistance over time.A number of studies have shown that microbial fermented feed can increase the content of feed nutrients,reduce the anti-nutrient factors in plant protein sources,improve the utilization rate of feed,and ingestion of fermented feed can improve the health level of animal body and enhance immunity.In addition,the microorganisms contained in fermented feed can inhibit the growth of pathogenic bacteria and protect the intestinal health of cultured animals.Therefore,this study explored the optimal fermentation conditions of cotton meal and the effects of different proportions of fermented feed on growth performance,antioxidant capacity and intestinal microorganisms of Macrobrachium nipponense,in order to provide reference for the application of fermented feed in Macrobrachium nipponense.1 Optimum fermentation conditions of cottonseed mealIn order to explore the optimum conditions of complex bacteria fermentation of cottonseed meal,Lactobacillus rhamnosus,Bacillus subtilis,Enterococcus lactis and Saccharomyces cerevisiae were selected as experimental fermentation strains in this experiment.Single factor and orthogonal tests were carried out with acid-soluble protein as the index.The results showed that the optimal ratio between strains was Lactobacillus rhamnosus: Saccharomyces cerevisiae: Bacillus subtilis: Enterococcus lactis as 10 : 5 : 1 : 1 respectively.With fermentation time,fermentation water,fermentation bacteria concentration and proportion of molasses added as four single factors,five levels were set for each factor to carry out single factor test on cottonseed meal.According to the results of single factor experiment,three levels of each factor were selected to carry out orthogonal test.The results showed that the main and secondary factors affecting acid-soluble protein of cotton meal were: fermentation time > molasses added ratio > fermentation water > fermentation bacteria concentration.The optimal fermentation conditions for cottonseed meal were: fermentation 3 d+2.5% molasses+40% water content +1.0E+06 CFU/g bacteria concentration.The results of optimum fermentation conditions of cottonseed meal showed that after fermentation,the content of beneficial microorganisms was increased,the contents of acid-soluble protein and small peptide in cotton meal were significantly increased(P<0.01),the proportion of molecular weight less than 2000 peptide was increased from 67.67% to 77.57%,and the contents of tannin,phytic acid and free gossypol were significantly degraded(P <0.01).2 Effects of fermentation complex strains on feed nutrients,antitrophic factors and digestive enzyme activities of Macrobrachium nipponense feedIn order to investigate the effects of composite bacteria fermentation on dietary nutrient composition and dietary digestive enzyme activities of Macrobrachium nipponense,the composite bacteria were used to ferment feed of Macrobrachium nipponense under optimal conditions.The results showed that: after fermentation,the contents of total bacteria,bacillus,enterococcus and lactic acid bacteria were significantly increased,while the content of mold was inhibited.Tannin content was significantly decreased(P<0.01);Phytic acid content decreased but had no significant difference(P>0.05);The contents of soluble protein and small peptide were significantly increased(P<0.01);Alpha-Amylase,lipase and neutral protease contents were all increased significantly(P<0.01).3 Effects of fermented feed on growth performance,antioxidant capacity and intestinal microorganisms of Macrobrachium nipponenseIn order to explore the effects of fermented feed on growth performance,antioxidant capacity and intestinal microorganisms of Macrobrachium nipponense,five experimental groups were designed as follows: L1 group(100% basal feed),L2 group(87.5% basal feed +12.5% fermented feed),L3 group(75% basal feed +25% fermented feed),L4 group(50% basal feed +50% fermented feed)and L5 group(100% fermented feed).M.nipponense of(0.09±0.01)g with similar size was selected for 56 d culture experiment.The results of culture experiment showed that the survival rate of all groups was above 80%,and there was no significant difference(P>0.05).The weight gain rate was increased first and then decreased.The weight gain rate of L3,L4 group was significantly higher than that of the control group(P<0.05),and the feed conversion ratio of L3 group was significantly lower than that of control group(P<0.05).The SOD activity of L3,L4 and L5 groups was significantly higher than that of L1 group(P<0.05),the MDA content of L2,L3 and L4 groups was significantly lower than that of L1 group(P<0.05),the superoxide anion clearance rate of L2 and L5 was significantly higher than L1 group(P<0.05),and the superoxide anion clearance rate of L4 group was significantly lower than that of L1 group(P<0.05).The contents of serum ALT,AST and ALB were significantly lower than that of control group(P<0.05),and the content of RUEA in L1 and L2 groups was significantly higher than that of other groups(P<0.05).GLU content in L2,L3 and L4 groups was significantly higher than that of L1 group(P<0.05).There were no significant differences in the contents of total triglyceride(TG),total cholesterol(TC)and total protein(TP)among all groups(P>0.05).The intestinal microbial results showed that the OTU number,Observed species index,Shannon index,and Chao1 index of group L3 were higher than that of group L1(P<0.05).PCA results showed that the community structure between group L1 and L3 was significantly different.At the genus level,the abundance of Aeromonas in group L1 was significantly higher than that in group L3(P<0.05),and the abundance of Diverbacter and Bacillus in group L3 was significantly higher than that of group L1(P<0.05).These results indicate that fermented diet could increase nutrient content,weight gain rate,reduce feed conversion ratio,improve antioxidant capacity and intestinal microbial community structure,and inhibit pathogenic bacteria in prawns.The suitable addition ratio of fermented feed is about 25%.In conclusion,the results show that microbial fermented feed can improve the quality,protein utilization and digestive enzyme activities of cottonseed meal and feed.The addition of 25% fermented feed could increase the weight gain rate,antioxidant capacity and intestinal microorganisms diversity of Macrobrachium nipponense.