Genetic Variants of β-casein Gene in Indigenous and Exotic Dairy Cattle Breeds in Sri Lanka

Background: Bovine milk contains two types of β-casein (CSN2); A1 and A2, in which A1 type has shown associations with certain health issues. This study was conducted to identify the abundance of CSN2 A1/A2 variants in European and indigenous dairy breeds in Sri Lanka.Methods: The study included 123 Ayrshire, 101 Holstein Friesian and 92 indigenous White cattle (Bos indicus) populations. Genotyping was performed by PCR-RFLP method using Dde1. Allele and genotype frequencies and population genetic indices were calculated.Result: Results showed A1A2 to be predominant in both Holstein Friesian (0.63) and Ayrshire (0.68) populations while A2A2 (0.82) was predominant in the White cattle population. A1 and A2 allele frequencies were 0.52 and 0.48 in Ayrshire; 0.39 and 0.61 in Holstein Friesian and 0.09 and 0.91 in White cattle populations. Ayrshire and Holstein Friesian populations showed significant deviation from the Hardy-Weinberg equilibrium (p£0.05). When compared to the imported breeds, the White cattle population showed inbreeding and less genetic diversity.