Finding the needle in the haystack: DSM29784 as a direct fed microbial for broilers

Usage of probiotics for animal production has increased in recent years as a means to improve efficiency. Strict regulatory restrictions limit what bacterial strains can be used as probiotics, including prohibiting genetic modification. Probiotic candidates need to be discovered from natural sources rather than engineered in the lab. Following a series of screening tests involving over 900 Bacillus candidates, and based on safety and efficacy characteristics, a single naturally-isolated Bacillus subtilis strain called DSM29784 was identified. A series of performance trials showed that B. subtilis improved BWG and FCR in broilers. To better understand the mode of action of this probiotic, a study was carried out with broilers raised for 42 days while recording performance parameters. The intestinal microbiota and intestinal mucosa were also analyzed. Birds receiving B. subtilis DSM29784 had significantly improved feed conversion ratio (-5.4%, p<0.0001) and body weight gain (+5.7%, p=0.001) compared to controls. Gut bacterial communities in treated birds showed a diverse microbiota containing increased relative abundance of beneficial members in the cecum, including butyrate producers such as Ruminococcus (p=0.0375) and Lachnoclostridium (p=0.0291). Birds fed B. subtilis DSM29784 also had improved intestinal lining measured by significantly longer microvilli in both the ileum (p<0.001) and cecum (p<0.001). These studies have increased our understanding of the mode of action of B. subtilis DSM29784 as an effective probiotic. They have also illustrated that several mechanisms can contribute to improved animal health, including beneficial interactions between probiotics and the host, and between probiotics and the resident microbiota.