Effect Of Probiotics On The Growth, Immune And Intestinal Microbial Communities Of Broilers

[Objective] The paper was conducted to study effect of growth, immune function, digestive enzyme activity and intestinal microbial communities of broilers which fed with probiotics made by two Bacillus, respectively.[Method] 100 7-day-old avian broilers were randomly devided into five groups,20 broilers each group. Control group chickens were fed the basic diet. Antibiotic group chickens were the fed basic diet supplemented with 0.1% sulfate neomycin. Manna group chickens were fed the basic diet supplemented with 0.2% manna. Pab02 group and PAS38 group chickens were fed the basic diet supplemented with 0.1% Bacillus subtilis Pab02 additive and 0.1% Bacillus cerecus PAS38 additive, respectively, the germ-containing quantity of diet was 1×106cfu/g. The broilers were immunized with newcastle vaccine (ND vaccine) at 8,21 day age.10 broilers per group were to observe the growth performence in whole period.5 broilers were chosen randomly from each group at 4,6 week age.5ml of blood were collected from wing vein. Then, the chickens were sacrificed by bloodletting from carotid artery and immune organs (spleen, thymus, bursa), the jejunum and ileum were taken out. The level of HI antibody against ND, immune organ index, digestive enzyme activity were determined respectively. The intestinal microflora was counted by using viable count and the intestinal microbial structure was analyzed by using PCR-DGGE.[Result] 1. The final weight, net gain, average day weight gain of broilers in two bacillus group were significantly higher than control group and manan group (P<0.01), antibiotic group were significantly higher than control group (P<0.01) and higher than manan group (P<0.05), manan group were significantly higher than control group (P<0.01). The growth improvement rate at 17-28 day old of each group were highest in whole period, in which the growth improvement rate of Pab02 group was the most significant, then PAS38 group. At the initial feeding period, the improvement of feed gain ratio by using probiotics was not significant than using antibiotics, but probiotics Pab02 and PAS38 had good effect on decreasing feed gain ratio in the middle and later period, in which PAS38 group had the highest improvement on feed gain ratio in 3,4 week and 5,6 week.2. At 4,6 week age, the index of thymus, spleen and bursa of Fabricius of probiotics Pab02 and PAS38 were improved compared with control group, all the immune organ index were higher (P<0.05) or significantly higher (P<0.01) than control group at 4,6 week age except the spleen index of Pab02 group at 4 week age. The level of HI antibody against ND of probiotic group were higher than control group, antibiotic group and manan group at 4 and 6 week age. There were significant different between PAS38 group at 4 week age and Pab02 group at 6 week age with control group(P<0.05).3. The amylase activity of jejunum, ileum, their intestinal wall and the proteinase activity of jejunum, ileum could be improved (P<0.05) or significantly improved (P<0.01) of Pab02 group and PAS38 group, compared with control group. There was no effect on amylase activity but it could decreased the proteinase activity of jejunum and ileum at 4,6 week age of antibiotic group. The amylase activity could be improved to some extent and the proteinase activity in ileum could be significantly improved at 6 week age (P<0.01).4. Probiotics of Pab02 and PAS38 had the effect of improving Lactobacillus spp. and Bifidobacterium spp., inhibiting reproduction of E.coli, and decreasing the amount of aerobic bacteria. It had increasing tendency on the effect of adjustment of Lactobacillus spp. and Bifidobacterium spp. from upper to inferior segment of intestine of broiler. They could increase (P<0.05) or significantly increased (P<0.01) the amount of Lactobacillus spp. and Bifidobacterium spp. at 4,6 week age than control group, and the effect of adjusting the intestinal microflora was better than 2 week age.5. The band numbers of each intestine of Pab02 group and PAS38 group were more than control group at 4 week age, and there are few characteristic bands could be seen; The band numbers of duodenum, jejunum was increased (P<0.05) and the band number of cecum of Pab02 group was significantly increased (P<0.01) than control group at 6 week age. The band number of duodenum was increased (P<0.05), the band number of jejunum and cecum were significantly increased (P<0.01) of PAS38 group. The density of intestinal microflora of broiler at 6 week age was decreased than 4 week age, but the number of band which had high abundance and the characteristic band were increased compared with 4 week age. The highest similarity of each group was increased at 6 week age than 4 week age, the stability of intestinal microbial structure had an increasing trend; the similarity of microflora structure of duodenum, jejunum, ileum and cecum had an decreasing trend in each group.[Conclusion] The results indicated that the immune function and small intestinal enzyme activity, the growth of beneficial bacteria such as lactobacillus and bifidobacterium could be improved, the regrowth of E.coli and aerobic bacteria could be inhibitted by using the additive probiotics Pab02 and PAS38 in feeding broilers. It had an good effect of adjusting the intestinal microflora, improved the growth of broilers, which could instead of antibiotic additive during the feeding period.