Effects Of Engineering Bacteria WB800N-CC31,Enterococcus Faecium And Their Complex Bacteria On Growth And Intestinal Flora Of Calves

In this study,24 weaned Simmental calves with similar body weight and 3 to 4 months of age were selected in a single factor completely randomized trial design.Calves were randomly divided into 4 groups: engineering bacteria group A,Enterococcus faecium group B,compound bacteria group C and control group D,and each group had 6 repeats,one cow per repetition.The control group was fed the basal diet,the engineering bacteria group A was fed the basic diet WB800N-CC31 engineering bacteria,the Enterococcus faecium group B was fed with the basal diet Enterococcus faecium.Compound bacteria group C fed WB800N-CC31 engineering bacteria and Enterococcus faecium in basal diet(the ratio of engineering bacteria to Enterococcus faecium was 1:1),and the addition of probiotics was 2 × 1010 CFU/d per cow.In this study,the effects of probiotics on growth performance,apparent digestibility of nutrients,serum biochemistry,immune index,rumen fermentation parameters and gastrointestinal microflora of weaned Simmental calves were investigated by animal experiments.The results show that:(1)During the whole experimental period,each probiotics group had no significant effect on daily weight gain,feed intake and feed weight ratio of weanling calves(P > 0.05).Addition of probiotic bacteria to calves diet had no significant effect on ADF,NDF,GA,P,CP,DM digestibility.At 20 and 60 days of experimental period,the digestibility of EE in compound bacteria group was significantly higher than that in the other three groups(P < 0.05),and at 40 days in experimental period,the digestibility of EE in compound bacteria group was significantly higher than that in the other three groups(P < 0.05).The digestibility of Ash in the engineering bacteria group was significantly higher than that in the other three groups(P < 0.05).(2)There was no significant difference in serum TP,ALB,AST,TG,BUN concentration among the treatment groups.At the 20 th day of the experimental period,the serum ALT concentration in the engineering bacteria group was significantly higher than that in the control group(P < 0.05).The serum Ig A concentration of calves in probiotics group was significantly higher than that in control group(P < 0.05),but had no significant effect on Ig G,Ig M,IL-2,IL-4 concentration(P > 0.05).(3)At 30 days,there was no significant difference in rumen p H,protein,ammonia nitrogen and volatile fatty acids between the probiotics group and the control group(P > 0.05).On the60 th day,the concentration of ammonia nitrogen in Enterococcus faecium group was significantly higher than that in control group(P < 0.05).(4)The microbial diversity and flora composition of rumen and intestine of calves were analyzed by high throughput sequencing.The results showed that probiotics had no significant effect on Chao1 index,ACE index and Shannon index of fecal flora diversity.The Chao1 index and ACE index of rumen flora diversity in Enterococcus faecium group and compound bacteria group were significantly higher than those in control group(P < 0.05).The main microflora in rumen and feces of calves were thick wall bacteria and pseudomycetes,and there was no significant difference in flora composition between probiotics group and control group(P >0.05).To sum up,adding different probiotic bacteria to the diet of Simmental weanling calves had little effect on daily weight gain,feed intake and feed-weight ratio of calves,and had little effect on apparent digestibility of nutrients and rumen fermentation parameters.The effect of fecal and rumen microbial composition was not significant,but it could significantly improve the immunity of calves and improve the diversity of rumen microorganisms in calves,which was beneficial to the gastrointestinal health of calves,and the effect of engineering bacteria group and compound bacteria group was the best.