Effects Of Bacillus Subtilis On Growth Performance And Rumen Microflora In Holstein Cows

Pathogenic Escherichia coli is a common pathogen in production and farming,and the bacteria is sensitive to sulfonamides,streptomycin and chloramphenicol,but easy to develop resistance,which is part of the reason why it is so prevalent and difficult to eradicate in production and farming.The biological antagonism between Bacillus subtilis and e.coli is one of the hot research directions in recent years.Bacillus subtilis,as one of the two kinds of bacillus allowed as feed additive by the ministry of agriculture of China,has been increasingly developed into microecological preparation for feeding due to its dual functions of antibiotics and enzymes.Because its preparation is non-toxic,non-residue,non-pollution of the green additive,in the green animal husbandry production has a broad prospect.And has been widely used in animal husbandry and feed industry,showing great social and ecological benefits.However,there is no clear direction for the selection of strains suitable for cows feeding,which could bring significant production benefits.After screening the seed liquid of 63 strains of Bacillus subtilis in the laboratory,the two strains with similar activities of lipase,amylase,cellulase and protease,but weak and strong inhibition of e.coli growth,were finally identified and renamed as strain W(weak bacteriostatic)and strain S(strong bacteriostatic),respectively.During the experimental period,when the TMR(Total Mixed Rations)diet was stirred every morning,the bacterial liquid was sprayed on the feed evenly and stirred evenly.Through the feeding experiment of 39 11-month old(±15d)cows for 60 days,we found that the addition of Bacillus subtilis in the diet significantly increased the body weight of11-month old cows compared with the control group(P = 0.04),and the bacteria-inhibiting strain had a better effect on cows.Moreover,in terms of blood indicators,compared with the weakly bacteriostatic strains,the supplementation of the diet with strong bacteriostatic strains significantly reduced the content of serum albumin(Alb)(P < 0.01).The serum levels of immunoglobulin A(IgA)and immunoglobulin G(IgG)were significantly increased(P <0.01).The results showed that supplementation of Bacillus subtilis with strong bacteriostasisin the diet could improve the health level of young cows and enhance the immune function of the body.In terms of the microbial flora of tumor-gastric juice,the Bacillus subtilis with strong bacteriostasis reduced the growth of harmful bacteria such as Campylobacter and Staphylococcus in tumor-gastric juice,increased the content of functional bacteria such as Clostridium XlVa,Lachnospiracea_incertae_sedi Jand Pseudobutyrivibrio,improved the rumen environment,and improved the health level of animals.