Effects Of Bacillus Amyloliquefaciens TL On The Growth And Caecum Microbiota Of Broilers

Bacillus amyloliquefaciens is gram positive bacteria and has high homology with bacillus subtilis. It can produce various enzymes and has antibacterial effect, so there are widely used in animal production. In this study, Bacillus amyloliquefaciens TL was added to the poultry feed as probiotic additives to explore its effects on the growth and caecum microbiota of broilers.In this study, a total of 180 Cocc 500 broiler chickens were divided randomly into three groups: control group( basal diet), antibiotics group( aureomycin intervention), probiotics group(Bacillus amyloliquefaciens TL intervention). These broiler chickens were fed for 35 days. The results of this research as follows:1、Growth performance: The broilers of antibiotics group and probiotics group weighed 16.02% and 13.40% respectively higher than control group on the 35 th day, and the feed conversion ratio of antibiotics group and probiotics group broilers decreased by 19.31% and 19.80% respectively compared with the control group while there was no statistically significant difference among three groups on broilers’ body weight at the first day. These results showed that Bacillus amyloliquefaciens TL intervention improved the average weight of broilers and feed conversion rate. Meanwhile, the growth promoting effect of Bacillus amyloliquefaciens TL intervention was the same with aureomycin.2、Serum biochemical indexes: On the 7th day, the content of blood glucose(GLU) in probiotics group was significantly higher than antibiotics group(P<0.01), while no significant difference with the control group(P>0.05); on the 21 th day, the content of GLU in probiotics group was increased by 11.55% and 11.55% compared with the antibiotics group and control group(P<0.01); However, there was no significant difference among three groups on the 35 th day about the content of GLU. As for total protein(TP) and albumin(ALB), probiotics group increased by 5.07%(P<0.05) and 15.09%(P<0.01) respectively compared with the control group on the 35 th day. The content of Serum urea nitrogen(BUN) of probiotics group and antibiotics group were significantly lower than that of control group on the 35 th day(P<0.05), and probiotics group and antibiotics group decreased by 16.87% and 19.28% respectively compared with the control group on the 35 th day. At 35 days of age, the content of cholesterol(CHOL) and triglyceride(TG) were significantly lower than control group(P<0.05), while were no significant difference with antibiotics group. These results showed that Bacillus amyloliquefaciens TL can promote the synthesis of protein and lipid metabolism, and it was beneficial to body’s normal physiological function.3、Immune organ index: The spleen index of probiotics group was increased by 10.94% and 13.04% respectively compared with the control group on the 14 th and 21 th day. The thymus index of probiotic group and antibiotics group were increased by 16.36% and 27.64% respectively compared with the control group on the 14 th day, and the thymus index of probiotic group and antibiotics group were increased by 23.96% and 31.25% respectively compared with the control group on the 21 th day. As for the bursa of fabricius index, probiotics group was significantly higher than that of control group(P<0.05) both at 14 and 21 days of age. At 35 days of age, the immune organ index among three groups were no significant difference. These results suggested that Bacillus amyloliquefaciens TL intervention can effectively stimulate and maintain the growth and development of broiler immune organs, and the promoting effect on immune organ weight of chickens was obvious.4、Intestinal morphology: At 7 days of age, the cecum villus height of probiotics group was significantly higher than that of control group(P<0.05), but was no significant difference with antibiotics group(P>0.05). At 21 days of age, the villus height and VH/CD ratio of cecum and ileum of probiotic group were significantly higher than that of control group and antibiotic group(P<0.05). At 35 days of age, the VH/CD ratio of cecum and ileum of probiotic group were significantly higher than that of control group and antibiotic group(P<0.05). These results demonstrated that Bacillus amyloliquefaciens TL intervention can improve intestinal morphology to enhance the capacity of the body for digestion and absorption of nutrients.5、Cecum microflora structure: Hi Seq high-throughput sequencing analysis of 16 S r DNA showed that the bacterial communities of antibiotics group and probiotics group was similar but significant different with control group. Firmicutes, Bacteroidetes, Proteobacteria, Tenericutes were dominant, but vary with age in differernt groups. At 21 days of age, at the genus level, Oscillospira 、Ruminococci and Butycicicoccus of probiotics group were significantly higher than that of control group, while Bacteroides and Lactobacillus of probiotics group were lower than that of control group; At 35 days of age, Clostridium and Faecalibacterium of probiotics group were significantly higher than that of control group, however, Prevotella and Parabacteroides of probiotics group were lower than that of control group. These results indicated that Bacillus amyloliquefaciens TL intervention influenced the cecum microflora structure of broilers, increased the number of bacterias which can produce volatile fatty acids, so what was beneficial for the growth and immunity of the host.