| Lactobacillus have been widely used in food,medicine,animal breeding and planting areas because of their advantages in improving the intestinal flora,promoting host health,substituting antibiotics and so on,and have become a new productivity in traditional industries,driven the related industrial transformation to a healthy,green direction.L.plantarum P-8 is a potential probiotic strain originally isolated from traditional fermented dairy products in Inner Mongolia of China.This study was conducted to investigate the effect of Lactobacillus plantarum P-8 on the growth performance,antibiotic residue,antibiotic resistance genes,gut microbiota,intestinal microbiota maturation of broilers in the scale breeding.The final results are following:180,000 broilers(Arbor Acres,AA)were randomly divided into three groups(antibiotic group,probiotic group 1 and probiotic group 2).All the broilers in three groups were fed Lincomycin,of which the probiotic group 2 was treated with a half dose.Meanwhile,broilers in the two probiotic groups were fed L.plantarum P-8.The results showed that compared with the antibiotic group,the survival rate,average weight and water consumption of broilers in the probiotic group 1 were significantly higher(p<0.05);the pH,shatole,indole,protein content of fecal and feed conversion ratio were significantly lower(p<0.05);the slaughter index such as muscle shearing force and water loss rate were significantly lower(p<0.05);the abdominal fat ratio was significantly lower(p<0.05);the spleen development was significantly higher(p<0.05),and there were no significantly differences in thymus and bursa development(p>0.05);the newcastle disease antibody titer was significantly higher(p<0.05);the lincomycin residue in muscles was significantly lower(p<0.05),which 0.797pμg/kg and0.330pg/kg in leg muscle,0.523μg/kg and 0.177μg/kg in breast muscle separately in the antibiotic group and the probiotic group 1.There was no significantly difference between the two probiotic groups(p>0.05).The fecal microbiota of broilers in the antibiotic group and the probiotic group 1 was mainly composed of Firmicutes,Proteobacteria.Bacteroidetes and Tenericutes(accounted for 99.5%of the total sequencing),and the ratio of Firmicutes and Bacteroidetes of broilers fecal microbiota in the antibiotic group was significantly higher than that of probiotic group 1(p<0.05).At genus level,the broilers fecal microbiota of the two groups was mainly composed of Lactobacillus、Enterococcus,Corynebacterium,Bacteroides,Trichococcus,Erysipelothrix,Facklamia,Oligella and Ignatzschineria(accounted for 58.34%of the total sequencing),however,significantly more Lactobacillus,Enterococcus and Oligella but less Corynebacterium,Trichococcus and Gallicola were found in the probiotic group 1(p<0.05).The content of antibiotic resistance genes in antibiotic group was significantly higher than that in probiotic group(p<0.01).Protein sequences were compared with COG and KEGG databases,results showed that categories L(replication,recombination and repair),E(amino acid transport metabolism)and G(carbohydrate transport and metabolism)of 23 functional categories were existed in each group,and the relative number of gene sequences from categories P(inorganic ion transport and metabolism),C(energy production and conversion),N(cell modification)and A(RNA processing and modification)of probiotic group 1 was significantly higher than that of antibiotic group(P.N and A:p<0.05;C:p<0.01).In addition,the activity in flagellar assembly(KO 02040)and bacterial secretion system(KO 03070)of 25 different metabolic pathways of probiotic group 1 was significantly higher than that of antibiotic group(p<0.05).To explore the mechanism of L.plantarum P-8 in large-scale broiler breeding,270 broilers(Cobb500)were randomly divided into control group,probiotic group(L.plantarum P-8)and antibiotic group(salinomycin and chlortetracycline),the intestinal microbiota of broilers were studied using metagenomics sequencing analysis technique during 42 days’ culture period.PERMANOVA test and Spearman,s correlation coefficient based on Meta-Storm distance revealed that feed additive(L.plantarum P-8 or antibiotics),time point and individual difference have a significant effect on the fecal microbiome structure,and feed additive is the most important contributor.The intestinal microbiota of broilers was divided into 29 age-discriminatory taxa and a shortlist of 16 top genera was used for the subsequent construction of the microbiota-based model for Intestinal Microbiota Maturation Index(IMMI).The probiotic group had a significant advance(IMMI=15)compared with control group(IMMI=30)and antibiotic group(IMMI=40),and the relative abundance of entire genera were found significantly higher in probiotic group than that of antibiotic group(p<0.05).In contrast to the antibiotic,L.plantarum P-8 strengthened the correlation among the bacterial genera,Network centralization were 0.3 15、0.28 and 0.375 respectively in control group,antibiotic group and probiotic group,and promote the gut microbiota into stationary phase.The mechanism of L.plantarum P-8 in large-scale broiler breeding can be concluded according to the above results:1.L.plantarum P-8 advanced the intestinal microbiota of broilers into stationary phase,and then improved the feed digestibility and nutrients synthesis efficiency,promoted the development of physiological organs(especially spleen and other immune organs),reduced the feed conversion ratio,fecal skatole,indole and protein content.2.Good development of physiological organs improved the immunity and accelerated the metabolic rate,increased water consumption,decreased the mortality and lincomycin residues in muscle.3.Besides the probiotic and its addition(adding 2.0×106CFU/mL of L.plantarum P-8 in drinking water),the broiler species,basal diet formula,breeding scale and antibiotics were quite different in the two tests,but the same results obtained that the growth performance of probiotics group was better than that of control group and antibiotic group.That is.the excellent breeding effect of L.plantarum P-8 is effective and reproducible.The model of Intestinal Microbiota Maturation Index(IMMI)was proposed firstly in the broiler breeding field in this study,namely the time required that the stable genera which total contribution rate over 50%reach a steady state.L.plantarum P-8 promotes the development of broiler intestine,immune organs and other physiological organs,furtherance the coordinated development of economic and ecological benefits,and provides theoretical evidence and basics for application. |
