An Analysis Of The Intestinal Flora Of Laying Hens At Different Egg Production Levels And The Screening And Application Of The Probiotics For Egg Production

The main purpose of this study was to analyze the characteristics of intestinal flora of high-yielding and low-yielding laying hens by using 16S rDNA high-throughput sequencing technology,and to explore the relationship between laying rate and intestinal flora of laying hens.At the same time,analyzed the difference of intestinal flora between high-yielding layer hens and low-yielding layer hens,and screened out a potential probiotics that could be cultured in intestinal flora of high-yielding layer hens.The screened strain was applied to layer hens to detect its influence on production performance.The specific contents are as follows:1.The experiment analyzed the characteristics of intestinal flora of high-yielding layers and low-yielding layers through 16S rDNA high-throughput sequencing,and the study showed that the intestinal flora structure of high-yielding layers was significantly different from that of low-yielding layers.At the phylum level,the average relative abundance of Firmicutes in high-yielding layers was significantly higher than that in low-yielding layers(P<0.05),and proteobacteria was significantly lower than that in low-yielding layers(P<0.05).At the genus level,the average relative abundance of Lactobacillus was the highest in high-yielding laying hens,and was significantly higher than that in low-yielding laying hens(P<0.05).Lactobacillus was the most significant bacterium between the two groups.According to the Alpha diversity analysis,the diversity of intestinal flora of high-yielding laying hens was lower than that of low-yielding laying hens(P>0.05).Through the prediction and analysis of PICRUSt function,it can be seen that there are significant differences between the intestinal flora metabolism functions of high-yielding laying hens and low-yielding laying hens,which are mainly manifested in carbohydrate metabolism and amino acid metabolism.Spearman correlation network analysis showed that Lactobacillus in the intestinal tract of laying hens inhibited other dominant species.2.According to the 16S rDNA high-throughput results,Lactobacillus,as the first dominant bacteria in the intestinal flora of high-yielding laying hens,was also the bacteria with significant differences between the two groups,so it was selected as the target probiotics for this experiment.A Lactobacillus strain which could adapt to the environment of digestive tract of laying hens was selected from the intestinal tract of laying hens with high yield as the target probiotics to improve the laying rate.Through isolation and identification,16 strains of lactobacillus were screened out.Through acid resistance test and bile salt resistance test,it was found that lactobacillus strains S5 and S9 could better adapt to the digestive tract environment.Through cholesterol decomposition test,strain S5 had higher cholesterol decomposition ability than strain S9.Therefore,lactobacillus S5 was selected as the probiotics to promote the productivity of laying hens.S5 strain was identified as Lactobacillus oris by 16S rDNA sequencing.3.By adding different levels of Lactobacillus oris S5,select the optimal dose.The study found that the 1×10~7cfu/kg dose group presented the best performance,significantly increasing the rate of laying in the later stage of laying(P<0.05)and reducing the average weight of laying hens(P<0.05).The optimal concentration group(1×10~7cfu/kg)and the control group were tested for egg quality,ileal flora and serum hormones.The results showed that the addition of 1×10~7cfu/kg Lactobacillus oris S5significantly improved the eggshell quality(P<0.05),but reduced the egg protein height and the hough unit(P<0.05).Meanwhile,Lactobacillus oris S5 increased the average relative abundance of lactobacillus in layer ileum(P<0.05),decreased the average relative abundance of Romboutsia(P>0.05),and significantly decreased the serum E2and INS levels(P<0.05).This study illustrates the differences in intestinal flora that between high-yield and low-yield chicken layers,indicates that Lactobacillus supplementation may be an effective ways to improve the rate of the layers.And established a screening method for probiotics to promote the egg production rate of laying hens.The results also indicated that Lactobacillus oris S5 may affect the intestinal nutrition level and fat synthesis in laying hens,reduce fat deposition,and thereby improve the mechanism of laying rate in laying hens.