Association Study of Polymorphic Varients of Beta (B) Casein Gene with Milk Production Traits (Lactose, Snf and Density) in Malvi, Nimari, Sahiwal and H.F. Cross Breeds Cow

Abstract

Background: The most frequently observed forms of beta casein (β-Cn) in dairy cattle are A1 and A2. A2 β-Cn is recognized as the original β-Cn protein because it existed before a mutation caused the appearance of A1 β-Cn in European cattle (Bos taurus) a few thousand years ago. In cattle, beta-casein (CSN2) gene is highly polymorphic with at least 13 genetic variants known until now.Methods: Research work was carried out on 50 Malvi and 50 Nimari, 50 Sahiwal and 50 H F Cross bred cow. In present research work the PCR amplicons of 121bp were digested by restriction endonuclease enzyme DdeI, which recognizes G^AATTC sites. Present association study of polymorphic variants’ showed that the presence of no restriction sites for the enzyme DdeI in both Malvi and Nimari. So one band of 121bp was observed on the gel and such genotype was designated as A2A2 type. Whereas in Sahiwal and H F Crossbred showed two type of genotypes A1A2 and A2A2.Result: The result of RFLP revealed that the gene and genotypic frequencies of β-casein (CSN2) gene for A2A2 was 1.00 for both Malvi and Nimari breed of cattle but 0.00, 0.30 and 0.70 in Sahiwal and 0.00, 0.64 and 0.36 in HF crossbred cattle, respectively. Association study showed that the lactose per cent was significantly higher in Nimari as compared to Malvi and Sahiwal. Among all the four breeds of cattle, significantly lower SNF (%) and density was noticed in Malvi breed of cattle for A2A2 genotype compared to remaining three breeds.