"Pé-duro" (hard foot) is a rare breed of beef cattle of European (Bos taurus taurus) origin, originated in northern and northeastern Brazil. Y chromosome morphology, outer genital elements and other phenotypic characteristics were examined in 75 "pé-duro" bulls from the Empresa Brasileira de Pesquisa Agropecuária (Embrapa) herd in the Brazilian State of Piauí. The purpose was to investigate possible racial contamination with Zebu animals (Bos taurus indicus) in a cattle that has been considered closest to its European origin (B. t. taurus). The presence of both submetacentric and acrocentric Y chromosomes, typical of B. t. taurus and B. t. indicus, respectively, and the larger preputial sheath in bulls with an acrocentric Y chromosome indicated racial contamination of the "pé-duro" herd with Zebu cattle. Phenotypic parameters involving horn, dewlap, ear, chamfer, and coat color characteristics, indicative of apparent racial contamination, were not associated with acrocentric Y chromosome.
