Optimization Of Bacillus Coagulans Detection Method And Clinical Application Effect Of Bacterial Diarrhea In Piglets

Bacillus coagulans has many biological properties,such as promoting the absorption of nutrients and improving the structure of intestinal microbial flora,and is widely used in animal production as a feed additive.At present,there are some problems that limit its use,such as uneven product quality and lack of authoritative standards in the detection of Bacillus coagulans.Based on the previous work,this study optimized the detection method of Bacillus coagulans in feed microbial preparations from the aspects of medium composition and p H value,culture temperature and culture time,and promoted the application and promotion of Bacillus coagulans in animal feed production.In this study,piglets with diarrhea were used as the test animals,and the effects of different doses of Bacillus coagulans compound preparations on piglet production performance,intestinal development and intestinal flora structure were detected through piglet feeding experiments,in order to clarify the effect of Bacillus coagulans compound preparations on piglets.The following test results were obtained for the optimal additive dosage and clinical effect during growth:（1）Bacillus coagulans were identified by Gram stain microscopy,biochemical experiments and specific PCR amplification,and the isolated and purified strains were all Bacillus coagulans.（2）The optimal detection conditions were finally determined after screening and comparison,using a self-made modified nutrient agar medium（p H 5.5）supplemented with0.04%bromocresol violet,cultured at 50°C for 24 h for the plate count of Bacillus coagulans,and the method was better with higher accuracy and detection efficiency than other commercial culture medium and detection methods.（3）It was found that Escherichia coli and Salmonella were the main pathogens causing bacterial diarrhea in piglets based on the results of PCR detection of fecal samples of piglets with diarrhea.（4）Sixty weaned diarrhea piglets with an average body weight of 6.67±0.24 kg were divided into four groups,and fed for 30 days.Group A was common microorganism product group,group B was supplemented with high-dose Bacillus coagulans（additional amount of100 billion/ton）,group C was supplemented with low-dose Bacillus coagulans（addition amount of 20 billion/ton）,and group D was the blank control group.Compared with the control group,the non-replacement normal product group increased the average daily gain and average daily feed intake of the diarrhea piglets.After adding high dose of Bacillus coagulans,the contents of Ig A,Ig M and Ig G in serum were significantly increased.Bacillus coagulans can promote the secretion of immunoglobulin antibodies in the body.Compared with the blank control group or the non-substituted product group,the content of zearalenone and aflatoxin B₁in the Bacillus coagulans-added group（group II and group III）were significantly reduced,and there was no significant change on the content of vomitoxin and T2D toxin.（5）The adding Bacillus coagulans diet of piglets with diarrhea for 30 consecutive days can increase the abundance of intestinal species and the types of beneficial bacteria such as Lactobacillus,and the abundance of various functional proteins in the high-dose Bacillus coagulans addition group(10¹¹cfu/t)was higher than that of the other groups.These results indicated that Bacillus coagulans could regulate the balance of intestinal microflora and ensure the expression of various functional proteins.（6）The adding Bacillus coagulans diet(10¹¹cfu/t)to the feed can significantly increase the villus height and the ratio of villus height/hidden depth in pig duodenum.In summary,this study optimized the plate count method of Bacillus coagulans.The method improved the detection efficiency and accuracy.The study showed that long-term addition of Bacillus coagulans compound preparation to the basal diet of diarrhea piglets could improve the production performance of diarrhea piglets.It can also regulate the intestinal microflora and promote intestinal development.