áS2 casein gene polymorphism and association with milk production traits in Malvi and Nimari cattle of Madhya Pradesh

The aim of this study was to know the polymorphic variants and their association with milk production traits in Malvi and Nimari cattle of Madhya Pradesh at áS2 casein gene (CSN1S2) gene   locus. The PCR amplified products of 1267 base pair (bp) length were digested by restriction endonuclease enzyme EcoRV, which recognizes GAT^ATC sites. The 1267bp product was cut into two fragments of sizes 1150bp and 117bp.  All the tested samples yielded different results. Absence of restriction site at both the alleles that resulted in the appearance of single compact bands of size 1267bp was referred to as genotype AA. The samples exhibiting three fragments (1267bp/ 1150bp/ 117bp) were denoted as genotype AB.  The RFLP analysis carried out in above both of the breeds of cattle revealed dissimilar genotypic patterns. AA and AB genotypes were observed in Malvi and Nimari . The genotypic and gene frequencies of AA, AB and BB genotypes of áS2-casein gene (CSN1S2)/EcoRV locus was found to be 0.44, 0.56 and 0.00 in Malvi; 0.68, 0.32 and 0.00 in Nimari and the respective gene frequency for A and B alleles were found to be 0.72 and 0.28 in Malvi; 0.84 and 0.16 in Nimari. The frequency of A allele was found to be highest as compared to B allele in all the four breeds of cattle under the study. Chi-square values for testing correspondence between observed and expected genotypic frequencies at this locus were found to be non-significant in Malvi and  Nimari breeds of cattle. The above result indicated  that the populations of animals of above both breeds were in Hardy-Weinberg equilibrium at this locus. The association of polymorphic variants of áS2-casein gene (CSN1S2)/EcoRV in Malvi and  Nimari breeds of cattle with milk yield per lactation (L), daily milk yield (L) showed the  non significant difference was observed between mean MY(L) of AA and AB genotype of Malvi and Nimari and With respect of daily milk yield the  Nimari. However, the  Nimari breed showed significantly higher  daily milk yield than the Malvi breed of cattle.