Subclinical infectious bursal disease in an integrated broiler production operation.

摘要: A field study was designed to determine the prevalence of subclinical infectious bursal disease (IBD) in broiler chickens from a commercial poultry company. Bursae Fabricius (BF) two vaccinated and three nonvaccinated flocks were evaluated histologically, antibody profiles these matched parent breeder established. Lesions IBD, including lymphoid necrosis, stromal edema, infiltrates heterophils macrophages, first detected BF at 24 days age both chickens. At 41 days, all had lesions characteristic severe depletion, proliferation epithelial cells, mild fibroplasia. Although mean maternal levels (measured by enzyme-linked immunosorbent assay) broilers apparently protective through day 12, IBD antibodies decreased nonprotective (below 1,000) 16 or 20. Titers began increase 28 32 because exposure. Sentinel birds, placed with flocks, also developed titers. Broiler breeders low nonuniform Prevalence exposure high, existing vaccination programs not effective.