Determination of the zygosity of ev21-K in late-feathering male White Leghorns using the polymerase chain reaction.

The dominant sex-linked late-feathering (LF) gene, K, is of commercial importance for sex determination at hatch. Knowledge of the zygosity of sequences associated with K would enable breeders to more efficiently select homozygous grandparent LF males on the maternal side of the standard feather-sex cross because all of their progeny would be LF, whereas only half of the progeny from heterozygous grandparent males would be LF. A specific, polymerase chain reaction (PCR) assay is described that distinguishes White Leghorn K/K males from K/k+ males and obviates the need to raise all LF grandparent males to sexual maturity. Because the Z chromosome of some LF broiler breeders have, in addition to the endogenous virus gene, ev21, the wild type allele, which is termed the unoccupied repeat b (URb), this approach may not be applicable to some broiler lines.