Effects of inclusion of Bacillus subtilis (Gallipro) to energy- and protein-reduced diet on growth performance, nutrient digestibility, and meat quality and gas emission in broilers

A total of 816 1-day-old Ross 308 broiler chicks with an average initial body weight (BW) of 44.01 ± 0.62 g were used in a 6-wk feeding trial. Birds were blocked based on BW and randomly allotted to 1 of 6 dietary treatments (8 replicate pens per treatment with 17 birds per replication pen) in a 3 × 2 factorial arrangement with 3 levels of metabolizable energy (ME) and crude protein (CP) with constant amino acid (100% ME and CP, 98.8% ME and CP, and 97.6% ME and CP) supplemented with or without 500 g/ton of Bacillus-based probiotics. As a result of this study, a significant reduction (P < 0.05) in BW and an increment in feed conversion rate (FCR) were observed with the reduction in the diet density during finisher and overall experiment periods. During the growing and finishing periods, the birds fed probiotic supplemented diets were heavier (P < 0.05) than those fed diets without probiotic. The FCR was also improved (P < 0.05) in probiotic supplemented groups during these periods, but feed intake (FI) remained unaffected compared to birds without probiotic supplemented diets. The apparent total tract digestibility (ATTD) of dry matter (DM) tended (P = 0.051) to be lower in ME- and CP-reduced diets compared with control. In addition, the ATTD of nitrogen (N) and energy was significantly lower (P < 0.05) in ME and CP-reduced diets than the control diet. A trend in the reduction (P = 0.059) of NH3 gas emission from the excreta was observed for birds fed ME- and CP-reduced diets compared with control diets. In addition, birds fed probiotic supplemented diets also showed reduced (P < 0.05) NH3 emission compared to those fed diet without probiotic. In conclusion, inclusion of probiotic to ME- and CP-reduced diet improved performance, had comparable effect on meat quality, and reduced ammonia emission from the excreta. No interactive effects of diet types and probiotic were observed.