A DNA sequence that is present in both sexes of Artiodactyla is repeated on the Y chromosome of cattle, sheep, and goats.

We have cloned a 307-bp Sau3AI fragment of DNA from the bovine male genome by deletion enrichment. Although a single-copy homolog is present in the female cattle genome, the sequence (BRY.1) is repeated at a moderate and variable frequency only in males. This pattern occurs too in sheep and goats, but BRY.1 is found in equal amounts in both sexes of fallow deer and pigs, approximating single copy. The conservation of a homologous sequence over millions of years and its repetition exclusively on the Bovidae Y chromosome raise interesting questions concerning the origin, evolution, and possible function of this unusual element.