Thermotolerance, Nutrient Utilization And Growth Promoting Mechanism Of Bacillus On Broilers

The study was conducted to investigate the heat resistence of several Bacillus probioticsand pelleting resistence, and to compare the nutrient and energy utilization in probioticBacillus species-supplemented mash and pelleted diets for broilers. Besides, in order todetermine the effects of Bacillus probiotic as antibiotic substitution on broilers, a swarm studywas conducted to compare the difference between probiotic and antibiotic.Exp.1Three Bacillus species probiotics (B. subtilis, B licheniformis, and B. coagulans) andS. faecalis were keeped in water bath some time and pelleted at80℃after mixed into mashdiet at the level of0.03%, and then were determined the survival. The results of thisexperiment indicated：The survival of B. subtilis, B. licheniformis, B. coagulans, and S.faecalis at95℃for10min were88.43%,93.81%,93.31%, and0%(5min), respectively.The survival of B. subtilis, B licheniformis, B. coagulans, and S. faecalis after pelleting were91.92%,92.41%,92.92%, and4.42%, respectively.Exp.2Two hundred21-d-old AA broilers were randomly divided into20dietary treatmentsconsisting of5replicates of2birds each. The control diets included a mash control and apelleted control without probiotics supplementation. Every probiotic included six dietarytreatments involving mash and pelleted diets that contained corresponding probiotic at thelevel of100,200, and300mg/kg of diet, respectively. The results of this experimentindicated：Addition of3kinds of probiotics at increasing levels to both mash and pelleteddiets linearly increased (P <0.01) the apparent digestibility and true digestibility of DM, OM,and CP and all ME contents (AME, AMEn, TME, and TMEn). All broilers chickens fedpelleted diet had higher (P <0.05) DM, OM, and CP digestibility and ME contents thanchickens fed mash diet. In addition, the significance of improvements in DM, OM, and CPutilization and ME contents of broilers fed pelleted diet was lagged behind the mash diet.Exp.3A2×2factorial design (CP level and growth promotion) was conducted to the effectof B licheniformis probiotic as antibiotic substitution on performance of broiler. Six thousand1-d-old Shandong local cross broilers were randomly divided into4dietary treatmentsconsisting of6replicates of250birds each. The results of this experiment indicated：ADG on d22to35was significantly increased (P <0.05) in probiotic treatments. Broilers fed dietscontaining B licheniformis had higher PLM and lower PAF on d35(P <0.05), lower pHvalue in ileum, cecum, and rectal on d21(P <0.05), lower E. coli and higher lactic acidbacteria count (P <0.05), higher thymus index on d21and35and bursa index on d35(P <0.05), lower serum GLB, UN, and TG level on d21(P <0.05), lower serum AST level (P <0.05) on d21, higher serum ALP concentration (P <0.05) on d21and35. No significantdifferences were observed between H-CP and L-CP treatments. With probioticsupplementation, the increase in serum ALB was much greater in broilers fed the low-CPdiets than in those fed the high-CP diets (CP×probiotics, P <0.05), and no other interactionswere observed among treatments.All these results indicate: B. subtilis, B licheniformis, and B. coagulans had resistence ontempreture and pelleting. Addition of3kinds of probiotics at increasing levels to both mashand pelleted diets linearly increased (P <0.01) the nutrient and energy utilizations, whichindicated that the advantage of Bacillus as probiotics was not weakened by pelleting. Blicheniformis probiotic as antibiotic substitution had the increasing trend in growthperformance and slaughter performance, and significantly improved intestinal flora balanceand immune organs indexes, and played an important role in regulation of metabolic, finallypromoted the gowth of broilers by these ways.