Fowl adenovirus-induced different manifestations of the disease in two consecutive chicken breeding flocks in a poultry hall.

This study investigated an adenovirus infection in two consecutive breeding flocks in the same poultry hall. Thirty-six thousand one-day-old chickens of the ROSS 308 hybrid broiler type were kept together in one hall. The chickens in the first breeding flock during fattening did not show any clinical signs of the disease or increased mortality. Typical clinical signs of the adenovirus infection were seen in the second breeding flock. The signs included: depression, apathy, somnolence, a crouched position with a droopy head, fuzzy feathers, anaemic combs and wattles, sporadic nervous signs, and reduced weight gain. Increased mortality was recorded from 18 to 25 days of age, the higher mortality rate resulted from dehydration and exhaustion. The surviving chickens showed growth slightly below average by the end of the fattening period. The necropsies of the chickens in the first flock showed characteristic lesions for inclusion body hepatitis (IBH). Adenoviral gizzard erosions (AGE) were found mainly in the chickens of the second consecutive breeding flock. In both breeding flocks, FAdV-A was detected by polymerase chain reaction (PCR) in the liver and gizzard samples. The presence of fowl adenovirus B was not confirmed in the evaluated samples. The results showed lesions in the first flock typical for IBH, whereas the pathological changes in the second flock were characteristic of AGE.