Production Process Optimization Of Sporolactobacillus S1 And Its Effect On Growth Performance And Fecal Flora Of Piglets

During the weaning period of piglets,there are a variety of internal and external environmental stresses,which lead to disorder s of immune and digestive systems,imbalance of intestinal microflora and so on,resulting in high mortality of piglets.At the same time,the implementation of the "No antibiotics" policy makes the replacement of antibiotics become a research hotspot in recent years.Probiotics can not only participate in the normal digestion and absorption of nutrients in the body,but also regulate the structure of intestinal flora through their metabolites,improve the in testinal environment,and enhance the intestinal wall barrier function.Therefore,the screening and application of probiotics have attracted more and more attention.In the our previous study,a strain of probiotics Sporolactobacillus S1 was isolated and screened from the intestinal tract of pigs,which could be transplanted into the intestinal tract of piglets,and have a significant effect on relieving weaning stress of piglets.In order to improve its application during the weaning period of piglets,this study explored the growth conditions and processing technology of this strain,and studied the effect of its synbiotics on the pro duction performance and fecal flora of weaned piglets through large-scale feeding experiment,which will be uesful for the application of Sporolactobacillus S1 and its synbiotics in the production of weaning stress in piglets.The content is divided into the following three parts:1 Optimization of growth conditions for Sporolactobacillus S1This experiment optimized the culture conditions and growrth time for S1,aiming to increase the number of viable S1 in the culture.The screening of the optimal culture conditions included the pH and the amount of buffer of medium.The pH of medium was set at five levels,5.2,5.5,5.9.6.2 and 6.8(control).The amount of buffer was set at five levels,1,2(control),3,4 and 5 g/L.The incubation time was set at 12.16 and 20h.By measuring OD600,pH value,viable bacteria number and metabolites,when pH was 5.9,OD value was the highest at 16 h,pH was significantly decreased,and viable count,lactic acid and volatile fatty acid amount were the highest.When the buffer amount was 4 g/L,OD value was the highest at 16 h,pH was significantly decreased,and viable count,lactic acid and volatile fatty acid were the highest.Orthogonal experiments were performed by selecting the three preferred pH and buffer gradients from the above assays.The results showed that the optimal culture condition of Sporolactobacillus S1 was pH 5.9.the buffer addition was 4 g/L,and the optimal culture time was 16 h.At the optimum culture conditions and time,the viable count of S1 was(6.35±0.33)×109 CFU/mL.The results of this study provided basic data for the subsequent large-scale production and practical application of S1.2 Optimization of feedstuff process conditionsOn the basis of the above studies,this experiment aimed to screen the optimal processing process of Sporolactobacillus S1 and promoted its large-scale utilization in piglet breeding.In this experiment,the adsorption carriers of Sporolactobacillus S1 were firstly screened in the laboratory.The results showed that the adsorption and survival rates of the four carriers on the tested strains were significantly different.After the adsorption and drying,the survival rate of the bran was the highest(17.0%),and that of the corn germ meal was the lowest(1.6%).On this basis,the pelleting test was carried out on the adsorption effect of the optimum carrier bran.The effect of pelleting on the survival rate of the strains adsorbed by bran was further studied.The results showed that the survival rate of the strains adsorbed by bran was 8.6%before and after pelleting.The above results showed that bran could be used to adsorb Sporolactobacillus S1 in mass production,and the product could be added to feed due to its high survival rate before and after pelleting.The results of this experiment laid a foundation for the production and application of S1.3 Effect of S1 synbiotics on growth performance and relative abundances of bacteria in the feces of weaned piglets.On the basis of the above studies,this experiment aims to explore the effect of S1 synbiotics on growth performance and relative abundances of bacteria in the feces of weaned piglets.The experiment selected 960 piglets of the same batch of weaning at the age of 21 days.According to the random block design and the principle of similar size in the same column,the piglets were randomly divided into a control group and three experimental groups according to their weight,with three replicates in each group.Each repetition has 80 piglets.The control group was fed commercial feed without synbiotics.The experimental group added synbiotics composed of S1 into the feed,in which S1 was added at 3kg/ton,and the prebiotics were added at 150 g/ton.The experiment period was 23 d.Feed intake,body weight gain and diarrhea rates were recorded during the trial.Fecal samples were collected on days 0,7,14,and 23 for the analysis of pH,short-chain fatty acids,and lactate acid.Solid pH meter was used to determine the pH of fecal samples.Gas chromatograph was used to determine the concentration of short-chain fatty acids in fecal samples.Lactic acid kit was used to determine the concentration of lactic acid in fecal samples.16S rRNA gene high-throughput sequencing was used to analyze the bacterial flora structure in fecal samples.The results showed that,compared with the control group,on day 7,the concentration of acetic acid in the fecal samples of the experimental group significantly increased(P<0.05),the lactic acid concentration showed a rising trend(0.05<P<0.1),and Unclassified Lachnospiraceae significantly increased(P<0.05).On day 14,the concentrations of acetic acid and propionic acid in the fecal samples of the experimental group were significantly increased(P<0.05),the diversity and richness of the fecal flora were significantly increased(P<0.05),and the relative abundances of Ruminococcus,Lactobacillus,and Clostridiales were significantly increased(P<0.05).On day 23,fecal samples of test group pH has a downward trend(0.05<P<0.1),lactic acid concentration has a rising trend(0.05<P<0.1),the concentration of propionic acid increased significantly(P<0.05),the relative abundance of the Firmicutes decreased significantly(P<0.05),while the relative abundance of the Bacteroidetes significantly increased(P<0.05),Eubacterium,Prevotella genera increased significantly(P<0.05).The results showed that S1 synbiotics had no significant effect on the growth performance and diarrhea rate of weaned piglets,but it could improve the concentration of short-chain fatty ac ids and lactic acid,reduce the intestinal pH.change the intestinal flora community,and then regulate the intestinal health of weaned piglets.In summary,the optimized growth conditions of S1 were pH 5.9,butter 4 g/L,and growth time 16 h.Bran was the optimized carrier for the culture of S1 for pelleting,S1 synbiotics could increase the concentrations of short-chain fatty acids and lactic acid in the intestinal tract,reduce the intestinal pH,adjust the intestinal microbial community,regulate the intestinal environment,and improve the intestinal health.