Development Of Chicken Complex Probiotics And Its Effect On Growth,Immunity And Intestinal Flora Of Roman Chicken

Because the problem of drug residues and bacterial resistance caused by the abuse of antibiotics in poultry farming has seriously threatened human health and the ecological environment,it has become particularly urgent and important to develop a new type of green feed additive instead of antibiotics.Therefore,in this study,two strains of Lactobacillus with good antibacterial activity and one strain with good Bacillus production were isolated and selected from the cecum of broiler chickens.Compounds were formulated into compound microecological preparations,and the medium and fermentation conditions were optimized.The effect of the composite microecological preparation as a substitute for green antibiotics was explored through an animal application evaluation trial to investigate the effects of growth,immunity and intestinal flora on Roman chicken.The research content and results are as follows:1.Preparation of chicken-derived composite microecological preparationsNine strains of Lactobacillus and six strains of Bacillus were screened out from the initial intestine of Kang Chicken.Through further screening tests of antibacterial activity,enzyme production ability and stress resistance,2 strains of Lactic acid bacteria R1 and R7 with good antibacterial effect and 1 strain of Bacillus Y1 with good amylase production ability were finally obtained.Using MRS-CaCl₂ as a co-cultivation medium and the inhibition zone of the fermentation broth as indicators,the optimal concentration of bacteria for the mixed culture was 1:2:4.2.Optimization of culture medium and fermentation conditions of chicken-derived microenvironmentTaking the number of viable cells and antibacterial activity of the composite microecological preparations as indicators,screening of cheap carbon source and nitrogen source culture medium raw materials and obtaining optimized fermentation medium.The medium consisted of 1%sucrose,1%glucose,4%soybean meal,0.38%sodium chloride,0.38%dipotassium hydrogen phosphate,0.037%magnesium sulfate,0.008%manganese sulfate,and 0.02%calcium chloride.Based on the optimization of the culture medium,the effects of culture time,temperature,inoculum volume,and liquid volume on the number of live microbes and the production of antibacterial substances in the composite microecological preparation were analyzed.The results showed that the biomass and antibacterial activity of the fermentation broth were the highest after incubation for 14 h at32?in 2%inoculum and 30%liquid.3.Effect of chicken-derived compound microecological preparation on growth immunity and intestinal microbiota of Roman chickenFeeding Roman chickens with a 1.85�10 ⁸ CFU/mL composite probiotic resulted in optimal results.The results showed that:compared with the control group,significantly increased average daily gain?P<0.05?and significantly reduced The feed-to-weight ratio?P<0.05?;glandular index increased by 27.13%;spleen index increased by 12.23%;bursa index increased by 4.59%;It promoted the development of ileal villus in Roma chickens,increased the biomass of Bifidobacterium and lactic acid bacteria in the cecum,and inhibited the proliferation of E.coli.The results of ERIC-PCR analysis showed that the compound microecological preparation could increase the density and richness of the intestinal microflora of Roman chicken and maintain the microecological balance of the intestine.The above studies indicate that a micro-composite ecological preparation has been successfully prepared in this study.The preparation has a good application effect both in vivo and in vitro,and has a certain application value.