Effect of a Competitive Exclusion Culture in a Necrotic Enteritis Challenge Model in Broilers

Restrictions on the use of antibiotics in broiler chicken production have led to a resurgence in necrotic enteritis (NE) and heightened interest in non-antibiotic alternatives to control the problem. Probiotics, which are beneficial bacteria that improve the enteric microbial balance, and which range from defined single-organism products to complex mixtures of undefined normal gut flora (the latter known as competitive exclusion cultures) have been investigated as alternative control measures for NE, with varying results. In this study, a complex undefined competitive exclusion culture (Aviguard) was compared to bacitracin methylene disalicylate (BMD) in a NE challenge model. Male broiler chickens housed in floor pens were either treated with Aviguard on the day of hatch, fed rations containing 55 ppm of BMD, or untreated, then challenged with coccidiosis and Clostridium perfringens in a NE challenge model. One group was untreated and unchallenged. The challenge successfully induced NE as evidenced by challenge control having NE mortality (12%) and lesion scores (0.367). The Aviguard group had numerically lower lesion scores (0.267) and the Aviguard and BMD groups had significant lower mortality (8%; 9%, respectively). There were no significant treatment effects on adjusted feed conversion or body weight by 42 d. Poultry producers do not adjust feed conversion for mortality, therefore using this standard, the Aviguard treatment was the only treatment for which the feed conversion that was not adjusted for mortality was statistically the same as the unchallenged control group (1.653; 1.636, respectively).