Effect of Bacillus subtilis on growth performance, bone mineralization, and bacterial population of broilers fed with different protein sources

ABSTRACT The objective of this study was to investigate the impacts of Bacillus subtilis (BS), ATCC 6051a strain, as a probiotic bacterium in broiler diets based of two protein sources [soybean meal (SBM) and cowpea seeds (CWP)], on growth performance (GP), carcass traits, bone mineralization and microflora population (0 to 42 d age). The SBM and CWP starter, grower and finisher diets were tested in the presence or absence of BS (5.0 ×1011 CFU spores g-1 feed) in a 2 × 2 factorial arrangement of treatments in a completely randomized design. Broilers were randomly assigned to 4 dietary treatments with 6 replicate pens per treatment (20 chicks per pen). The results showed that broilers fed CWP had comparable GP (BWG, FI, and FCR) to the birds fed the SBM diet. Carcass, breast and legs' yield, organ size (i.e. gizzard, liver, pancreas, small intestine, caecum), and bone development were not affected by the protein source. The addition of BS in both types of diet improved BWG (P