Different strains of Clostridium perfringens cause different levels of severity of necrotic enteritis in broiler chickens

Necrotic enteritis (NE), mainly caused by the gram-positive anaerobic bacterium Clostridium perfringens (Cp), is an enteric disease with great economic impact for the broiler industry. The prohibition of in-feed antibiotics has resulted in an increase in NE incidences globally. The severity of the disease in broilers depends on many factors. However, the type of Cp strains used plays a critical role. This study examined the impact of two Cp strains, i.e. NE18 and NE36, on performance, lesion score and gut permeability of broilers. Ross 308 broilers (n = 468) were assigned to a 2 × 3 factorial design (Feed: With/Without antibiotic) × (Challenge: No / NE18/ NE36). Oral administrations of Eimeria species (d9) and two stains of Cp (d14) were used to induce NE in the challenged groups. On d16 two birds from each pen were inoculated with FITC-d and serum samples were subsequently obtained for leaky gut evaluation. FITC-d amount was measured using a microplate reader (Synergy HT, Multi-mode microplate reader, BioTek Instruments, Inc., VT, USA). Broiler performance (Feed Intake, FI; weight gain, WG; and feed conversion ratio, FCR) was analysed for d0-24 period. Intestinal lesion scoring and gut permeability were measured at d16. Weight gain in the challenged group was significantly lower (P < 0.001) compared to the unchallenged birds at d24. Challenge also reduced the FI significantly (P < 0.001). FCR was significantly higher in the groups challenged with NE18 (P < 0.001) and NE36 (P < 0.001) compared to nonchallenged birds. Antibiotic diets significantly decreased FCR (P < 0.05) and increased WG (P < 0.05) in all groups. Birds challenged with NE36 showed higher FCR (P < 0.001) compared to the birds challenged with NE18 indicating a more severe impact of the NE36 than NE18. Ileal lesion scores and gut permeability were not significantly different between the two strains, but numerically higher number of lesions and gut permeability were observed in birds challenged with NE36. Supplementation with antibiotics reduced (P < 0.05) gut permeability in the birds of all groups. The findings of this study indicate that the severity of necrotic enteritis disease in challenge model can be modulated by the use of different Cp strains.