Distribution of the Beta-Casein Gene Variants in Three Cattle Breeds Reared in Benin

Abstract

The beta-casein gene is one of the most functional genetic candidate that affect milk quality and composition traits. Among its variants, the A1/A2 are the most common. Therefore, the aim of this study was to identify the distribution of the Beta-casein gene variants (A1/A2) in three different cattle breeds in order to determine which of the breed produce a better milk for consumers’ health. 152 blood samples which comprises 72 (Muturu), 40 (Azawak) and 40 Girolando were used to carry out this study. Genomic DNA was extracted from the blood samples and each variant was subsequently amplified from the extracted DNA samples using an Allele-Specific PCR technique and then confirmed by running the PCR products on 1% agarose gel. The result showed that there were three genotypes (A1A1, A2A1 and A2A2) in the three breeds. The average percentage genotypic frequencies obtained from this study were 42.76%, 31.58% and 25.66% respectively for A1A1, A1A2 and A2A2 genotypes while the percentage allelic frequencies were 58% and 42% respectively for A1 and A2 allele. The genetic parameters of Azawak breed were higher than that of the other breeds, what implies that there was a higher polymorphism and genetic diversity in the Azawak breed in the beta-casein gene compare to the other breeds. The A2 beta-casein variant in milk has been found to be desirable for milk consumer’s health and nutrition. This study therefore showed that the Azawak breed provides a good potential for increasing this favorable allele through appropriate breeding techniques of cattle.