Potentials of Bacillus subtilis-derived surfactin to improve performance, intestinal health and welfare of broilers under necrotic enteritis challenge

This study evaluated the potential of Bacillus subtilis-derived surfactin (SRF) on broiler performance, intestinal health and welfare parameters under necrotic enteritis (NE) challenge. A total of 512 d-old Cobb 500 broiler chicks were allocated into four treatment groups, with eight replicates each. The treatments were: NC, non-challenged control; CC, NE challenged control; SRF, CC + surfactin at 0.01 %; and ANT, CC + antibiotics: zinc bacitracin and salinomycin across all feeding phases. Birds were fed a wheat-soybean meal-sorghum-based diet supplemented with xylanase and phytase. The NE challenge was induced by oral gavage of Eimeria spp. on d 9 and NetB-producing Clostridium perfringens on d 14 and 15. The results showed that before the challenge, average weight gain (AWG), average feed intake (AFI) and feed conversion ratio (FCR) were not different among the treatments (P > 0.05). During post-NE challenge (d 8-19) and overall period (d 0-35), AWG and FCR were compromised by NE, with increased intestinal lesions and serum fluorescence isothiocyanate dextran (FITC-d) concentrations on d 16 in the CC group than NC group (P < 0.05), indicating a successful sub-clinical NE challenge. Birds fed ANT had higher AWG and lower FCR, intestinal lesions and serum FITC-d concentrations than the CC group (P < 0.05). Supplementation of SRF significantly improved FCR (P < 0.05) during d 28-35, while during the overall period (d 0-35), SRF-fed birds showed AWG and production efficiency factor (PEF) that shifted towards those of the NC, being not significantly different (P > 0.05). Birds fed SRF had increased jejunal villus height and crypt depth ratio (VH:CD), reduced duodenal lesion and footpad dermatitis scores than CC group (P < 0.05). Additionally, SRF supplementation shifted serum FITC-d, litter moisture, litter, hock burn and jejunal lesion scores towards the levels comparable to NC and ANT groups (P > 0.05). These findings suggest that surfactin may have the potential to support recovery from the NE, enhancing performance, intestinal health, and overall welfare in broilers.