Comparison of multiple methods for induction of necrotic enteritis in broilers. I

Abstract

SUMMARY A variety of necrotic enteritis (NE) research methodologies exist in the literature, many with components that do not represent standard industry practices. The models tested here aimed to investigate multiple NE methods that represent common broiler production systems. Two preliminary experiments compared Eimeria maxima (EM) plus NetB-negative Clostridium perfringens (CP) and NetB-positive CP (CPB), and showed decreased BW gain (BWG) relative to non-challenge negative control (NC; P ≤ 0.05) across NE models, but no difference in NE lesion scores. Experiments 3 and 4 tested 2 EM strains (EMG or EMM6), CP, 3 CPB strains, washed CPB, or supernatant from washed CPB to determine the impact of NetB toxin when birds consumed a standard corn-soy diet. Groups with predisposing EM had the largest decrease in BWG (−19.50 to −28.35%) compared to the NC in experiment 3. Experiment 4 showed similar trends in EM groups with −20.88 to −22.09% change in BWG (P ≤ 0.05). Minimal % change in BWG occurred in all CPB groups, with less than 10% decrease. Increasing the amount of CP in feed to 2 L/d for 4 consecutive days resulted up to 17% decrease in BWG (P ≤ 0.05), but lesion scores were not significantly different than NC. When administered in the absence of EM, CP, regardless of the presence of NetB gene and inoculum, did not cause clinical NE in these experiments. A predisposing factor, such as EM, was required for development of clinical signs, gross macroscopic lesions, and decreased BWG when broilers were fed a standard diet.