Chickens of four strains of the White Leghorn breed were introduced, selected by the RIF test, and raised in an isolated chicken house. As a result, a flock of chickens free from avian leukemia virus (ALV) was produced and maintained successfully.
1. Of 140 chickens introduced, 42 were subjected to the RIF test. Of them, 35 birds (83.3%) were free from ALV. All of them, except 3 C/B birds (7.1%), were susceptible to viruses of groups A and B. No C/A chickens were found
2. Neutralizing Antibody against group A viruses was detected from 16 of 24 birds, but that against group B viruses was from no birds.
3. Hereditary susceptibility to group E viruses was found in 20.0% and resistance to the same viruses in 66.7%. Both properties were noticed in 13.3%.
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