A Poultry Subclinical Necrotic Enteritis Disease Model Based on Natural Uptake.

Necrotic enteritis (NE) in poultry is an opportunistic infection caused by . Well-known as a multifactorial disease, NE development is under the influence of a wide range of environmental risk factors that promote the proliferation of pathogenic at the expense of nonpathogenic strains. Current NE challenge models typically incorporate pre-exposure to disease risk factors, in combination with exogenous inoculation. Our goal was to enhance current models using a natural uptake of from the barn environment to produce a subclinical infection. We incorporated access to litter, coccidial exposure (either 10× or 15× of the manufacturer-recommended Coccivac B52 vaccine challenge; provided unspecified doses of , and two strains of ), feed composition, and feed withdrawal stress, and achieved the commonly observed NE infection peak at 3 weeks post-hatch. NE severity was evaluated based on gut lesion pathology, clinical signs, and mortality rate. Under cage-reared conditions, 15× coccidial vaccine-challenged birds showed overall NE lesion prevalence that was 8-fold higher than 10× coccidial vaccine-challenged birds. NE-associated mortality was observed only in a floor-reared flock after a 15× coccidial vaccine challenge.