A SURVEY OF THE VIRAL FLORA OF 2 COMMERCIAL PEKIN DUCK FLOCKS

Ducklings on a problem farm which showed persistent and unacceptably h igh mortality yielded a larger range and greater number of viruses tha n did ducklings from a second flock, in which mortality was of a power and acceptable level. Reoviruses were the viruses most frequently iso lated from young birds from both farms, but for longer at the problem site. ELAs (Embryo Lethal Agents), named since they caused high mortal ity in chick embryos, but could not otherwise be characterized, were r ecovered frequently and throughout the growth cycle of the problem flo ck, but not at all in the other flock. Lentogenic Newcastle disease vi rus was detected at all ages on the problem farm but less often than E LAs. The faeces of birds on the problem farm yielded rota-like viruses , corona-like viruses and adeno-like viruses, and on the farm with nor mal mortality, Egg Drop Syndrome-76 virus and adenovirus. Detection te chniques included culture on chick embryos and chick embryo liver cell s, and electron microscopy (EM). Inoculation of whole eggs was particu larly valuable and more successful than cell culture for virus recover y. EM was most useful for direct examination of faecal preparations an d confirmation of the viral type.