Effect Of Direct-Fed Microbials On Performance And Intestinal Health Of Broilers

The experiments were conducted to evaluate the effect of direct-fed microbials onperformance, nutrient utilization, intestinal morphology and cecal microflora in broilers.Experiment1: Effect of direct-fed microbial and antibiotic on performance andintestinal health in broilers. A total two hundred and eighty-eight1-day-old male broilerswere randomly allocated to four treatments to examine the effect of using Bacillusamyloliquefaciens-based direct-fed microbials (DFM) to replace antibiotic in late growthstage on performance, nutrient digestibility, cecal microflora, and intestinal morphology.Each treatment had eight cages with9birds per cage. Experimental diets were fed at starter(d1to21) and finisher (d22to42) phases. The experimental diets were:1) NC: negativecontrol group fed basal diet without any antibiotics;2) PC: positive control group fed basaldiet with200mg/kg zinc bacitracin;3) DFM30: this test group fed basal diet with200mg/kgzinc bacitracin from d1to21and30mg/kg DFM from d22to42;4) DFM60: this testgroup fed basal diet with200mg/kg zinc bacitracin from d1to21and60mg/kg DFM fromd22to42. The results showed that the addition of DFM increased body weight gain (BWG)and improved feed conversion ratio (FCR) as compared to NC (P <0.05). Generally, PC,DFM30and DFM60groups showed increased apparent total tract nutrient digestibility fordry matter (DM), crude protein (CP), and apparent metabolizable energy (AME). DFMdecreased cecal Escherichia coli population versus NC, and increased the population ofLactobacillus than PC. PC, DFM30and DFM60groups increased villus height and the ratioof villus height to crypt depth compared with NC.Experiment2: Effect of different direct-fed microbials and antibiotic on performanceand intestinal of broilers. The present study was conducted to evaluate the effect of thedietary supplementation of different DFMs on growth performance, nutrient utilization,intestinal morphology and cecal microflora in broiler chickens. A total of five hundred andseventy six1-day-old male broilers were randomly allocated to one of eight experimentaltreatments in a completely randomized design. Each treatment was fed to eight replicate cages, with nine birds per cage. Dietary treatments included an antibiotic-free basal diet(control), and basal diet supplemented with either15mg/kg of virginiamycin as antibioticgrowth promoter (AGP),30mg/kg of DFM A,60mg/kg of DFM A,200mg/kg of DFM B,200mg/kg of DFM C,30mg/kg of DFM D or4000mg/kg of DFM E. The broilers fed dietswith the DFMs and virginiamycin had better BWG and FCR than that of control (P <0.05).Supplementation of virginiamycin and DFM significantly increased the apparent total tractdigestibility of CP, DM and AME during both starter and finisher phases (P <0.05). Theaddition of DFMs significantly increased villus height and villus height to crypt depth ratio inall intestinal segments compared to control. However, the addition of virginiamycin resultedin similar or significantly lower (P <0.05) villus height, crypt depth and villus height to cryptdepth ratio compared to the control group. Both DFMs and AGP groups decreased theEscherichia coli population in cecum at d21and d42(P <0.05). In addition, the populationof Lactobacillus were increased in DFMs groups compared to control and AGP groups (P <0.05).In conclusion, dietary supplementation with Bacillus amyloliquefaciens-based DFMduring d22to42enhanced performance although antibiotics were used over d1to21period.DFMs could assist in reducing the use of AGPs in broiler diets by increasing nutrientutilization, improving gut structure, and balancing intestinal microbial population.