Impact of Bacillus subtilis supplementation on growth, gut histology, and microbial genetic diversity in native and commercial chickens

Probiotics have gained increasing attention in poultry production as a sustainable alternative to antibiotic growth promoters.This study evaluated the effects of dietary Clostat (Bacillus subtilis) on growth, gut histology, meat quality, blood parameters, and gut microbiota in local Omani and Cobb 430 broilers.A 22 factorial design was employed, using the two chicken breeds and two dietary treatments: Control (basal diet) and Clostat (basal diet plus 0.05% Clostat).Clostat significantly enhanced weight gain, feed intake, and feed conversion ratio in the two breeds over 42 days (p<0.05).Clostat also increased serum total protein levels in both breeds, as well as white blood cell count, red blood cell count, heterophils, and lymphocytes in Omani chickens (p<0.05).In addition, the villus height and villus-to-crypt ratio in the jejunum and ileum of both breeds were also enhanced by dietary Clostat (p<0.05).Furthermore, the carcass yield and weight of internal organs were significantly improved in Clostat-treated animals of both breeds (p<0.05).Microbial community analysis revealed distinct profiles in the jejunum and ileum of both breeds, suggesting that each segment developed a specific bacterial community with varying relative abundances.In conclusion, Clostat supplementation at a rate of 0.05% improved growth performance and general health status in both Cobb 430 and Omani chickens.Further research is recommended to determine the optimal Clostat dosage for local chickens to enhance growth performance.