Evaluation of the Efficacy of NuPro®-Yeast Extract in Reducing Intestinal Clostridium perfringens Levels in Broiler Chickens
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The etiological agent of necrotic enteritis (NE) is Clostridium perfringens (CP). Traditionally, NE is controlled with in-feed antibiotics. However, increasing consumer demand for drug-free poultry has fostered the search for non-antibiotic alternatives. Yeast extract contain nucleotides that are immunomodulatory and also essential for cellular functions. Two experiments were conducted to evaluate the efficacy of NuPro®-yeast extract in reducing intestinal CP levels in broiler chickens. In the first experiment one hundred and ninety two day-old male broiler chicks were obtained, and randomly assigned to 6 treatments in a battery cage trial. Treatment 1 (CX) consisted of chicks fed corn-soybean meal (SBM) basal diet without added bacitracin methylene disalicylate (BMD) or NuPro®. Treatment 2 (CM) consisted of chicks fed corn-SBM basal into which BMD was added at 0.055 g/kg. Treatment 3 (CN) consisted of chicks fed corn- SBM basal supplemented with NuPro® at 2% level for the first 10 days of experiment. Treatments 4 (PX), 5 (PM), and 6 (PN) consisted of chicks that were challenged with 3 mL of CP inoculum (~107 cfu/mL) on days 14, 15, and 16 of experiment, and fed diets similar to treatments 1, 2, and 3, respectively. On days 1 and 7 post-challenge, intestinal CP levels, lesion scores, and alkaline phosphatase activity (ALP) were assessed. On day 1 post-challenge, CP level in PM treatment (2.09 log10 cfu/g) was lower (P < 0.05) compared to the PX treatment (4.71 log10 cfu/g), but similar to PN treatment (2.98 log10 cfu/g). A similar trend was observed on day 7 post-challenge. NuPro® supplementation enhanced ALP activity (P < 0.05) in CP-challenged chicks, and appeared to reduce intestinal lesion scores. Although dietary supplementation of NuPro® in PN treatment reduced CP levels by 1.73 log10 cfu/g and 0.68 log10 cfu/g compared to PX treatment on day 1 and day 7 post-challenge, respectively, these reductions were not statistically significant. Based on the results of this experiment, we hypothesized that extending the period of NuPro® supplementation beyond the first 10 days of life should be considered for achieving significant reduction in intestinal CP levels. In Experiment 2, a 42-day floor pen trial was conducted. Eight hundred day old male broiler chicks were obtained from a commercial hatchery and randomly assigned to 8 treatments. Treatment 1 (CX) consisted of chicks fed corn - SBM diet without BMD or NuPro® added. Treatment 2 (CM) consisted of chicks fed corn-SBM basal into which BMD was added at 0.055 g/kg. Treatment 3 (SN) consisted of chicks fed corn-SBM basal into which NuPro® was added at 2% level for the first 10 days of the experiment. Treatment 4 (LN) consisted of chicks fed corn-SBM basal into which NuPro® was added at 2% level throughout experiment. Treatments 5 (PX), 6 (PM), 7 (PSN) and 8 (PLN) consisted of chicks fed diets similar to those given to CX, CM, SN and LN treatments respectively, and were additionally challenged with 3.5 mL of CP inoculum (~108 cfu/mL) on days 14, 15, and 16 of experiment. On days 1, 7, and 21 post-challenge intestinal CP levels were assessed. Results showed that by 21 days post challenge, the NuPro®-containing diet fed throughout the experiment (PLN) significantly reduced intestinal CP levels (P < 0.05) by 1.50 log10 cfu/g compared to NuPro®-free PX treatment. Conversly, the magnitude of intestinal CP reduced in the PM (1.19 log10 cfu/g) and PSN (1.32 log10 cfu/g) treatments were not statistically significant. In conclusion, dietary supplementation of NuPro® fed throughout the growout effectively reduced intestinal CP during broiler production cycle.