A multi-microbe probiotic formulation processed at low and high drying temperatures: effects on growth performance, nutrient retention and caecal microbiology of broilers.

1. Two experiments were conducted to evaluate a multi-microbe probiotic formulation processed at low (LT) or high (HT) drying temperature. 2. In both the experiments, 640 d-old Ross male chicks were randomly allotted to 4 treatments on the basis of initial BW for 35 d experiments. 3. In experiment one, dietary treatments were a negative control (NC; basal diet without any antimicrobial); positive control (PC; basal diet +10 mg/kg avilamycin); basal diet with 0·3% probiotic LT; and basal diet with 0·3% probiotic HT. 4. Improved overall weight gain, FCR and retention of CP were observed in birds fed the PC and probiotic diets when compared with birds fed the NC diet. At d 21, birds fed the probiotic and NC diets had more caecal Bifidobacterium and total anaerobes than birds fed the PC diet; while birds fed the PC and probiotic diets had fewer caecal Clostridium than birds fed the NC diet at d 35. 5. In experiment two, a 2 × 2 factorial arrangement of treatments was employed to evaluate the effects of two concentrations of probiotic HT (0·30 or 0·60%) and avilamycin (0 or 10 mg/kg). 6. Birds fed the 0·60% probiotic HT diet showed improved overall weight gain and CP retention, higher Lactobacillus and Bifidobacterium in the caecum, and reduced Clostridium and coliforms in the caecum. Inclusion of avilamycin improved the overall weight gain and feed intake, and reduced the caecal Clostridium and Bifidobacterium population. 7. In conclusion, high drying temperature had no effect on the efficacy of the multi-microbe probiotic formulation; while the probiotic HT formulation was more effective at the 0·60% level. Moreover, inclusion of avilamycin improved performance of birds but did not have any interaction with probiotics.