S97 Evaluation of Essential Oils and Organic Acids in Diets for Broiler

necropsy, the proventriculi are enlarged with thickened walls. Microscopically, the glands are dilated, with necrosis of secretory cells, hyperplasia of ductular epithelium and mucosal and glandular inflammation caused by lymphocytic infiltration. The mucosa has cystic lesions and expansion of the lamina propria. These microscopic inflammatory lesions are distinct from lesions caused by noninfectious causes of enlarged proventriculi. Currently, the cause of this condition is not known. Studies have implicated viruses such as reovirus, adenovirus, infectious bronchitis virus and infectious bursa disease virus (IBDV). A proventricular homogenate (2054) that originated from clinically ill broiler from northern Alabama caused both gross and microscopic lesions typical of TP at 14 days post infection (PI) of one-day-old SPF broilers. Proventriculi of 2054-infected chickens were significantly enlarged and the lesions were consistent with those seen in commercial chickens diagnosed with TP at the Alabama State Diagnostic Laboratory. Infected chickens did not seroconvert to IBDV. Moreover, on the 14th day PI, IBDV RNA was not detected and bursa did not atrophy; their size and weight were the same as controls. Microscopic examination of the bursae showed neither lymphocytic depletion nor inflammatory reaction typical of IBD. The TP agent was present in the 2054 homogenate and it may not be IBDV, as evidence of IBDV was not apparent when TP was fully reproduced. This agent(s) that caused TP will be isolated, purified and identified, then re-inoculated back into chickens with the main goal of fulfilling Koch’s postulates to ascertain etiology of TP.