| The gut microbes carry out functions that are critical for host physiology,including nutrition,growth,development and immunity.Among them,the so-called“probiotics”are believed to regulate the balance of intestinal flora,promote the health and growth of animals,so as to reduce the use of antibiotics.It is of great significance for scientific breeding,improving the health and production capacity of breeding stocks,which are the basis of the animal husbandry,by studying the characteristics of the intestinal flora,by exploring and by utilizing the probiotic flora from those animals.After the high-throughput sequencing analysis on 16S r RNA,the results showed that the gut flora of local breeding pigs is distributed in 18 phyla,138families,and 308 genera.Among them,the dominant phyla are Firmicutes,Bacteroidetes,Proteobacteria and Spirochaetae;the dominant families are Prevotellaceae and Oscillospiraceae,Lachnospiraceae,Ruminococcaceae,and Spirochaetaceae;dominant genera are Escherichia,Shigella,Treponema,and Prevotella.After isolation,gram stain,catalase test,morphological observation and16S r RNA molecule identification,a total of 83 candidate probiotics were screened from 25 samples of fresh pig manure,which were collected from healthy breeding pigs(species boars,reserve sows,nursing sows,and pregnant sows)in different local areas.Those bacteria belong to lactobacillus,bacillus.Strains RU-18,RU-19,RU-20,RU-6,R-2,and M-11 had strong inhibitory effects on Escherichia coli,Staphylococcus aureus,Pseudomonas fluorescens and Listeria monocytogenes.Among them,RU-19,RU-6 and R-2 had better stress resistance,and RU-6 had the strongest adhesion to IPEC-J2 cells(15.21CFU/cell).The 72-hour fermentation of soybean meal was carried out with Enterococcus faecalis RU-19,Streptococcus alactolyticus RU-6,and Bacillus licheniformis R-2,which had showed better probiotic properties in previous tests.At the end of fermentation with single strain,the number of viable cells were3.15×10~7 CFU/g,3.75×10~8 CFU/g,4.1×10~8 CFU/g,respectively for strains of RU-19,RU-6 and R-2;when the fermentation with two strains finished,about4.2×10~8 CFU/g and 1.1×10~8 CFU/g of viable cells were found for R-2 and RU-19,respectively.Compared with raw material,in fermentation batches with RU-6,or RU-19,or R-2,or mixed R-2 with RU-19,the content of small peptides in soybean meal increased by 51.29%,40.85%,303.37%,and 46.8%,respectively.High performance liquid chromatography(HPLC)showed that the acetic acid content of RU-6 fermented soybean meal was the highest(9.14 mg/g);the lactic acid content of RU-19 fermented soybean meal was the highest(8.07 mg/g);the propionic acid content of R-2 fermented soybean meal was the highest(8.25mg/g);In addition,the anti-nutritional factors in soybean meal were reduced by8.8%,8.9%,4.18%,and 4.29%when fermented with RU-6,RU-19,R-2,and mixed bacteria,respectively.In summary,in this study we obtained preliminary information on the characteristics of the gut flora of local breeding pigs,and then got some probiotic intestinal flora by isolation,screening and identification.We then found more active probiotics,more small peptides,more organic acids,and less anti-nutritional factors in the soybean meal fermented with probiotic strains we picked out.As a result,the nutritional value of soybean meal was improved in fermentation.All these works will provide references for effective management of breeding pigs. |
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