An adenovirus survey of poultry flocks during the growing and laying periods.

Chicken adenoviruses were isolated from asymptomatic chickens on each of 7 farms tested; a majority of them induced cytopathology by the second serial passage. Although adenoviruses were isolated from chickens ranging in age from 8 to 34 weeks, the highest isolation rate was from those 8 to 14 weeks. Eight serotypes (1, 2, 4, 5, 6, 7, 8, and 9) were identified in a relatively small geographic area; serotypes 1, 4, 7, and 9 were isolated most frequently. Multiple serotypes were found on 6 of 7 farms, with 1 farm having 4 serotypes identified. Repeat isolations of the same serotypes were noted on 2 farms. The pattern of virus isolations was generally related to age but varied according to farm. Although new serotypes kept appearing, even after birds came into lay, no clinical problems were associated with them. The incidence of precipitin reactors tended to be low (10-40%) in immature birds but reached 80% or more after sexual maturity. The "antiserum pool" modification of the VN test was found to be accurate and less cumbersome than the conventional procedure for typing isolants.