Evaluation of the efficacy of yeast extract in reducing intestinal Clostridium perfringens levels in broiler chickens

The etiological agent of necrotic enteritis is Clostridium perfringens. Traditionally, necrotic enteritis is controlled with in-feed antibiotics. However, increasing consumer demand for drug-free poultry has fostered the search for nonantibiotic alternatives. Yeast extract contain nucleotides that are immunomodulatory and also essential for cellular functions. An experiment was conducted to evaluate the efficacy of NuPro yeast extract (Alltech Inc., Nicholasville, KY) in reducing intestinal C. perfringens levels in broiler chickens. One hundred ninety-two 1-d-old male broiler chicks were obtained and randomly assigned to 6 treatments in a battery cage trial. Treatment 1 consisted of chicks fed a corn-soybean meal basal diet (BD) without added bacitracin methylene disalicylate or NuPro. Treatment 2 consisted of chicks fed BD into which bacitracin methylene disalicylate was added at 0.055 g/kg. Treatment 3 consisted of chicks fed BD supplemented with NuPro at a 2% level for the first 10 d of the experiment. Treatments 4 (PX), 5, and 6 (PN) consisted of chicks that were challenged with 3 mL of the C. perfringens inoculum (approximately 10⁷ cfu/mL) on d 14, 15, and 16 of the experiment and fed diets similar to treatments 1, 2, and 3, respectively. On d 1 and 7 postchallenge, intestinal C. perfringens levels, lesion scores, and alkaline phosphatase activity were assessed. On d 1 postchallenge, C. perfringens level in treatment 5 (2.09 log₁₀ cfu/g) was lower (P < 0.05) compared with the PX treatment (4.71 log₁₀ cfu/g) but similar to the PN treatment (2.98 log₁₀ cfu/g). A similar trend was observed on d 7 postchallenge. NuPro supplementation enhanced alkaline phosphatase activity (P < 0.05) in C. perfringens-challenged chicks and appeared to reduce intestinal lesion scores. Although dietary supplementation of NuPro in the PN treatment reduced C. perfringens levels by 1.73 and 0.68 log₁₀ cfu/g compared with the PX treatment on d 1 and 7 postchallenge, respectively, these reductions were not significant. Extending the period of NuPro supplementation beyond the first 10 d of life should be considered for achieving significant reduction in intestinal C. perfringensg levels.