Isolation and characterization of Bacillus subtilis CH16 strain from chicken gastrointestinal tracts for use as a feed supplement to promote weight gain in broilers

Spore-forming bacterial strains were isolated from chicken gastrointestinal tracts to develop a heat-stable feed supplement that promotes weight gain in broilers. Seven Bacillus strains having more than 90% sporulation were screened from the isolates and identified to be closely related with Bacillus subtilis and Bacillus licheniformis. Of the seven strains, B.subtilis CH16 was selected to develop a feed supplement for broilers, because it formed 100% heat-stable spores, grew rapidly at 42 degrees C and quickly formed a biofilm. In large-scale trials in broilers (n1150 per group), the group fed CH16 (3x10(6)CFUg(-1)pellet) showed higher average daily gain (ADG=6116) and lower food conversion ratio (FCR=1696) than did the group fed B.licheniformis CH22 (ADG=5710 and FCR=1792), the group fed B.subtilis HU58 (ADG=5190 and FCR=1868), BioPlus group (ADG=5932 and FCR=1807) and the control group (ADG=5602 and FCR=1880). In conclusion, CH16 spores significantly increased ADG by 917% and reduced FCR by 979% in broilers. The result supports the use of B.subtilis CH16 of chicken intestinal origin as a feed supplement that promote weight gain in broilers. Significance and Impact of the StudyThis study reports screening of Bacillus strains isolated from chicken gastrointestinal tracts for development of a feed supplement that promote weight gain in broilers. Of the seven Bacillus isolates with high sporulation efficiency (90%), Bacillus subtilis CH16 strain showed the best growth and biofilm formation at body temperature of broilers (42 degrees C). In large-scale trials in broilers (n1150 per group), CH16 spores induced a 917% increase in daily weight gain (ADG) and a 979% reduction in FCR while the commercial BioPlus((R)) YC induced only a 589% increase in ADG and a 388% reduction in FCR.