Dropped egg production in ducks associated with adenovirus infection

Six thousand laying ducks were kept on a large-scale farm, half of which were home-reared ducks, and the other half were imported birds. At the beginning of the laying period 70% of the ducks reared on the farm possessed EDS antibodies in titres of 1:32 to 512, whereas only 20% of the imported ducks were found to possess haemagglutination inhibition (HI) antibodies in titres of 1:16 to 1:32. When the ducks reached the peak of egg production, a severe diarrhoea was observed and egg production decreased by 50% and 10% in the imported ducks and the home-reared ducks, respectively. The decrease in egg production lasted only for 1 week, and production then returned to a normal level. Shell-less and soft-shelled eggs were not recorded, but sometimes misshapen eggs were found. From small intestinal contents of ducks with diarrhoea a haemagglutinating virus identical with McFerran's adenovirus 127 was isolated. HI antibodies appeared in 100% of the convalescent sera. Hatching losses exceeded those observed in previous year by 20%. It may be presumed that the drop in egg production of laying ducks was caused by EDS virus infection.