The efficacy of bacitracin methylene disalicylate when fed in combination with narasin in the management of necrotic enteritis in broiler chickens.

The efficacy of bacitracin methylene disalicylate (BMD) in the management of necrotic enteritis (NE) when fed in combination with narasin was investigated in a floor-pen study of 2,000 broiler chickens using a Clostridium perfringens inoculum challenge model. Treatments consisted of 1) nonchallenged-nonmedicated; 2) challenged-nonmedicated; 3) challenged-narasin (70 ppm); 4) challenged-BMD (55 ppm); 5) challenged-narasin (70 ppm) + BMD (55 ppm). Medication was provided in the feed from Day 0 to trial termination on Day 41. C. perfringens challenge occurred from Day 14 to 16. BMD and narasin, fed alone and in combination, reduced (P < 0.05) mortality due to NE when compared to challenged-nonmedicated birds. NE lesion scores (Days 0 through 41) were lower among birds fed BMD and narasin, alone and in combination, compared to challenged-nonmedicated birds. Improvements in NE mortality and NE lesion scores were greatest for the BMD + narasin-medicated birds, followed by the BMD-alone, and then narasin-alone treated birds. BMD and narasin, alone and in combination, provided improvements (P < 0.05) in average daily gains over the entire study (Days 0 to 41). The results of this study demonstrate the effectiveness of BMD and narasin in the management of NE in broiler chickens.