Occurrence of beta-casein allele A1 in Bovidae species

Abstract

In the last two decades bovine beta-casein variant A1 has attracted attention in the dairy industry as a source of beta-casomorphin-7 opioid-like peptide with potentially harmful effects on human health. Because the origin of this variant is unknown, the aim of the study was to investigate its occurrence in different species of the Bovidae family. Blood samples were taken from 137 animals belonging to 17 Bovidae species. All animals were genotyped in beta-casein locus by Illumina Bovine MDv2 Chip. The results shown that allele A1 was present in Bos taurus cattle, including primitive cattle (Watusi and Ukraine) and in a modern dairy breed (Holstein). In Dahomey cattle, two heterozygous A1A2 individuals were found. In all remaining species, no animal carrying allele A1 of beta-casein was identified. It may be concluded that allele A2 is ancestral to allele A1 and was spread especially within modern dairy cattle