A Bacillus subtilis (QST 713) spore-based probiotic for necrotic enteritis control in broiler chickens

Abstract

Necrotic enteritis (NE) is a common poultry disease that significantly affects the profitability of commercial broiler production. Traditionally, antibiotic feed supplements are administered to poultry to combat the negative effects of NE. However, due to the ban on growth-promoting antibiotics in the European Union, increasing concern for antibiotic resistance, and demand for drug residue free poultry products, alternative approaches are necessary to maximize broiler performance against NE. A study was conducted to determine the efficacy of feeding Bacillus subtilis (QST 713) spores in broilers using an NE-induced challenge condition. High and low concentrations of B. subtilis (QST 713) spores (1 × 106 and 1 × 105 cfu/g of feed) in broiler feeds were used to identify the appropriate dose to overcome the adverse effects of NE. A treatment group supplemented with bacitracin methyl disalicylate (BMD) at a therapeutic level (50 g/t) was included to compare the efficacy of B. subtilis to a conventionally used antibiotic. Based on these results, NE was successfully induced in the nonmedicated broiler chickens orally inoculated with coccidial oocyst and Clostridium perfringens. Relative to the nonchallenged group, birds infected with NE with no medication showed a significantly (P < 0.05) decreased BW gain, increased FCR, increased NE lesion score, and increased NE mortality. Supplementation of B. subtilis at 1 × 106 cfu/g of feed and BMD mitigated the negative effects of NE in all production parameters and measures of NE infection. No significant differences (P > 0.05) were observed between NE-challenged birds fed with high dose of B. subtilis (QST 713) and those birds supplemented with BMD. Low dose supplementation (1 × 105 cfu/g of feed) of B. subtilis (QST 713) increased NE mortality (P < 0.05) relative to high dose supplementation. Overall, based on these data, adequate supplementation of B. subtilis (QST 713) could serve as an alternative approach in controlling NE infection in broilers without continuously depending on antibiotics during their growing period.