A Study Of Effects And Mechanisms Of Bacillus Licheniformis On Performance In Broiler

Purpose: Comprehensive observations of the effects and mechanisms of Bacillus licheniformis additive supplemented in basic diet on growth performances, blood biochemistry parameters, immune function, antioxidation function and histological morphology of intestine, protease in duodenum and microorganism flora of cecum in broilers.Research method: 300 one-day-old broiler chickens were randomly divided into five groups, each group included four replicates (15 broiler chickens per replicate). The control group ( groupⅠ)was fed with the basic diet. The treatment groups (groupⅡ,Ⅲ,Ⅳ) were fed by the basic diet supplemented with 50mg/kg, 100mg/kg, 200mg/kg of Bacillus licheniformis, respectively. The groupⅤ(antibiotics group) was fed by the basic diet supplemented with 30 mg/kg of zinc bacitracin and 6mg/kg of Colistin sulfate. The experiment duration was lasted for 70 days. Two stages of feeding programme were conducted, the first stage was from 0 day (one-day-old) to 4 weeks old and the second stage was from 5 weeks old to 10 weeks old. All groups were absolutely fed in same entironment including illumination, feeding procedure, water supply, temperature and moisture control and vaccinations.Results: 1,Growth performances: Average weight gains from 1 week old to10 weeks old are significantly improved (P<0.05 ) ; feed conversion rates from 1 week old to10 weeks old are significantly reduced (P<0.05 ) and improvement of dressing percentage is observed at 10 weeks old, but no difference is obtained (P>0.05) in groupⅡ(supplemented with 50mg/kg of Bacillus licheniformis) , compared with control group. Feed conversion rates from 1 week old to10 weeks old are significantly reduced (P<0.05 ) in groupⅡ,compared with groupⅤ(antibiotics group). No any differences are observed among groupⅠ, groupⅢ, groupⅣand groupⅤ(P>0.05).2,Blood biochemistry parameters:Uric acid and urea nitrogen are significantly reduced (P<0.05) and the total protein and albumin in serum are significantly incressed (P<0.05) at 4 weeks old in groupⅡ(supplemented with 50mg/kg of Bacillus licheniformis) , compared with control group; urea nitrogen in serum was significantly reduced (P<0.05) , total protein and activity of AKP in serum are significantly improved (P<0.05) at 10 weeks old in groupⅡ(supplemented with 50mg/kg of Bacillus licheniformis) , compared with control group. Compared to antibiotics group (groupⅴ),uric acid in serum is significantly reduced in groupⅡat 10 weeks old (P<0.05 ).3,Immune function: Indexes of spleen and thymus in groupⅡ(supplemented with 50mg/kg of Bacillus licheniformis) are significantly improved at 4 weeks old and 10 weeks old (P<0.05), and IgA secreting cells in duodenum are significantly increased (P<0.05), compared with control group.4,Antioxidation: Activities of T-SOD and GSH-Px in groupⅡ(supplemented with 50mg/kg of Bacillus licheniformis) are significantly improved at 4 weeks old and 10 weeks old (P<0.05), and contant of MDA is significantly reduced at 10 weeks old(P<0.05), compared with control group.5,Histological morphology and microorganism flora: Villus length, depth of crypt and thickness of mucous membrane in groupⅡ(supplemented with 50mg/kg of Bacillus licheniformis) are significantly inproved(P<0.05)at 10 weeks old, compared with control group. Predominance flora of Bifidobacterium adolescentis and Lactobacillus Beijerinck are obviously increased(P<0.05)and flora of E coli are obviously decreased (P<0.05)in cecum of in groupⅡat 10 weeks old, compared with control group.6,Protease in duodenum: Compared with control group, the activity of protease in duodenum is significantly increased in groupⅡ(P<0.05).Conclusion: 1.Bacillus 1icheniformis added to broiler diet can improve the performances of broilers.2.Bacillus1icheniformis added to broiler diet can improve the immune function, antioxidation, intestinal morphology and microorganism flora in cecum and protease in duodenum, indicating that Bacillus1icheniformis acts as growth promotor and enhances resistance against to some diseases.3 . The best added amount of Bacillus1icheniformis in broiler diet is 1.0×109CFU/kg feed.