Effect of Bacillus pumilus supplementation on performance, intestinal morphology, gut microflora and meat quality of broilers fed different energy concentrations

In this research trial, the effects of the dietary supplementation with a probiotic were evaluated in broiler chickens fed diets with standard or reduced (-4%) metabolizable energy concentration. A total of 640 day-old Ross-308 male chicks were allocated into four equal treatments with ten replicates each (16 chicks per pen). The control treatment (D1) was fed with the basal diets (starter 1−10 days, grower 11−24 days, and finisher 25−35 days). The second treatment (D2) was fed diets containing 4% lower metabolizable energy, compared to the control. The third treatment (D3) and fourth treatment (D4) were fed the diets of the first and second treatments, respectively, further supplemented with a probiotic (Bacillus pumilus) at the level of 7 × 10⁸ CFU (viable spores)/kg feed. All diets were supplied in mash form, and feed and water were provided to the birds ad libitum. The examined parameters included performance, gut histology, gut microbiota populations, welfare parameters (diarrhea and foot pad dermatitis scores), bedding material quality and carcass quality parameters. Two-way analysis of variance method (energy concentration x probiotic supplementation) was used for the statistical analysis. The main significant (P ≤ 0.05) effects of the lower energy diets were: decreased final body weight and weight gain; decreased ileum villus height and number of goblet cells; decreased counts of Bacillus spp in the ileum and the ceca; increased diarrhea score (day 24) and footpad dermatitis score (days 24 and 35); increased bedding material moisture and nitrogen concentration; change of carcass composition by lowering the fat percentage while increasing moisture and protein percentages; improved meat oxidative stability under refrigerated storage up to 4 days. Furthermore, the main significant (P ≤ 0.05) effects of the Bacillus supplementation were: increased final weight and weight gain, and improved feed conversion ratio; increased ileum villus height and number of goblet cells; increased counts of Lactobacillus and Bacillus spp in the ileum and the ceca; improved diarrhea score (days 10 and 24) and footpad dermatitis score (days 10 and 24); decreased bedding material moisture and nitrogen concentration; improved meat oxidative stability under refrigerated storage up to 4 days. In conclusion, the results showed that this probiotic supplementation of the diet can support broiler performance, welfare and meat quality. In addition, as treatment D4 had similar body growth and feed conversion with treatment D1, it appears that the probiotic supplementation had an energy sparing effect on the energy-diluted diets.