Effect of Paramyxovirus Yucaipa on Fertility, Hatchability, and Poult Yield of Turkeys

In view of the ambiguity in establishing paramyxovirus yucaipa (PMY) or antigenically similar yucaipa-like viruses as disease-causing agents (1,2,3,4), it is fitting to report the results of a controlled field trial conducted in 1966 in turkey breeder hens intentionally infected with PMY virus. During the 1960's, the owner of a turkey-breeding facility was in the process of improving his genetic stock for growth rate, confirmation, egg production, fertility, and hatchability. Breeder experiments were conducted on a small, isolated ranch using selected turkeys that were brooded and then reared on the same premises in groups of about 100 hens per pen. During the 1965-66 season, 8 pens of birds were available for the owner's genetic studies. We investigated the immune response of these birds to vaccination against fowl pox (EP) and Newcastle disease virus (NDV), but the results are not part of this report. Ten turkeys from each pen were bled at intervals and tested serologically for antibodies as previously described (1) to NDV, PMY, and avian influenza, T/meleagrium/64. During the laying period (December 1965 through February 1966), records of 100 eggs set showed that the hens in all 8 pens retained a high level of fertility, hatchability, and poult yield. Toward the end of the study, one pen of turkeys was exposed to PMY to determine the effects of the virus on laying turkey hens. On May 6, 1966, 86 turkeys in the last downwind pen (no. 8) were individually inoculated intranasally with 0.25 ml of PMY that