Eradication of exogenous avian leukosis virus from commercial layer breeder lines
Payne, L.N.; Howes, K.
Veterinary Record 128(1): 8-11
1991
ISSN/ISBN: 0042-4900 PMID: 1848381 Document Number: 367838
On the basis of earlier studies, a programme for eradicating exogenous avian leukosis virus from commercial poultry stock was devised and applied to 11 layer breeder lines. The eradication cycle started when the dams and sires were 50 or more weeks. Cocks were included in the testing programme because, although they are believed not to transmit ALV congenitally, infected birds could contaminate the environment and infect hens venereally. Two eggs per dam were tested by ELISA and dams whose eggs contained albumen with an optical density reading of 0.2 or more were not used to produce replacement chicks. Cloacal swabs and semen samples from sires were tested by ELISA and any sires giving positive reactions were not used for breeding. Meconium samples from day-old chicks were tested by ELISA in the hatchery and chicks with positive reactions were discarded. Chicks with negative reactions were transferred to the rearing farm and reared in isolation from sources of ALV infection. At 15 weeks old, cloacal swabs were tested by ELISA and reactors were eliminated. Plasma samples were tested for A and B subgroup antibodies to monitor for the presence of ALV infection. At 18 weeks old, the birds were transferred to laying cages on the breeding farm, and at point-of-lay (about 24 weeks) albumen samples from the first eggs produced were tested by ELISA and shedder hens were eliminated. Semen and cloacal swabs from sires were also tested by ELISA at 24 weeks and reactors were eliminated. Dams and sires were tested again at 50 or more weeks, at the start of the next eradication cycle. After three years of testing, avian leukosis virus infection was eradicated completely from all but one, a slow-feathering line.