Lyophilized Carnobacterium divergens AS7 bacteriocin preparation improves performance of broiler chickens challenged with Clostridium perfringens

The present study aimed to investigate the effects of Carnobacterium divergens AS7 bacteriocin (divercin AS7) on growth performance, digestibility, fermentation processes, selected microbial populations, and histomorphology in broiler chickens challenged with a mixture of 3 Clostridium perfringens isolates. In total, 480 one-day-old male Ross 308 chicks were randomly assigned to 4 experimental groups (12 replicate pens of 10 birds per treatment). The diets were either nonsupplemented or supplemented with a lyophilized preparation of divercin AS7. On d 18, 19, and 20, half of the birds were challenged twice a day with the C. perfringens mixture. The C. perfringens challenge did not influence broiler BW gain but impaired feed conversion ratio from d 29 to 42 (P = 0.023) and throughout the experimental period (P = 0.038). Moreover, the C. perfringens challenge resulted in decreased pH levels of crop, gizzard, and ileum contents (P < 0.05) and reduced the numbers of lactic acid bacteria in the ceca (P = 0.01). Divercin supplementation decreased broiler feed intake from d 14 to 28 (P = 0.001) but increased BW gain from d 29 to 42 (P = 0.048). The divercin supplementation increased the AME(n) level (P = 0.015) and reduced digesta pH in crop and ileum (P = 0.004 and P = 0.042, respectively), but of nonchallenged birds only. Divercin supplementation, moreover, increased gizzard lactate concentrations (P = 0.003). The crop concentrations of lactate and succinate and the ileum concentration of lactate were increased by divercin supplementation (P = 0.005, P = 0.027, and P = 0.002, respectively) and C. perfringens challenge (P = 0.034, P = 0.053, and P = 0.0002, respectively). Divercin supplementation decreased villus heights (P = 0.0006) and crypt depths (P = 0.044) in noninfected birds, whereas in challenged birds, villus heights (P < 0.0001) were increased. In conclusion, the present study demonstrated a very complex response pattern of broilers exposed to C. perfringens challenge and dietary divercin A57 supplementation, but it indicated that divercin AS7 may partly counterbalance the negative effects associated with C. perfringens.