Managing Broilers Gut Health with Antibiotic-Free Diets During Subclinical Necrotic Enteritis

Abstract Necrotic enteritis (NE) caused by Clostridium perfringens is among the most important enteric diseases in poultry production. This study examined the effects of two probiotics (Prob) and a synbiotic (Synb) during a naturally occurring NE challenge. On day (d) of hatch, 1200 Cobb male broilers were randomly allocated to five groups (8 pens/treatment, 30 birds/pen) including 1) negative control (NC): corn-soybean meal diet; 2) positive control (PC): NC + 453 g Stafac®20/907 kg feed; 3) Prob 1: NC + 453 g Prob 1/907 kg feed; 4) Prob 2: NC + 453 g Prob 2/907 kg feed; and 5) Synb: NC + 453 g Synb/907 kg feed. One day after placement, birds were challenged by a coccidia vaccine to induce NE. Feed intake and body weights were measured on d 8 (NE onset) and end of starter (d 14) and grower (28) periods. On d 8, the small intestines of three birds/pen were examined for NE lesions. Ileal mucosal scrapings from one bird/pen were collected on d 8 and d 28 to profile the microbiota using 16S rRNA sequencing. Data were analyzed in JMP or QIIME 2 and significance between treatments identified by LSD or linear discriminant analysis effect size (P