Effect of Butyrophilin Gene Polymorphism on Milk Quality Traits in Crossbred Cattle

A genetic polymorphism study on butyrophilin gene was carried out to explore variability of this gene and to estimate effects of such variability on milk quality traits in crossbred cattle. Polymorphism was unraveled by conducting Hae III PCR-RFLP of this gene. Three genotypes such as AA, BB and AB and two alleles namely A and B were observed in crossbred population. The frequencies of genotypes and alleles were 0.78, 0.17 and 0.04 for AA, AB and BB genotypes, respectively, and 0.87 and 0.13 for A and B alleles, respectively. The nucleotides, which have been substituted from allele A to B, were observed as C to G ($71^{st}$ nucleotide), C to T ($86^{th}$ nucleotide), A to T ($217^{th}$ nucleotide), G to A ($258^{th}$ nucleotide), A to C ($371^{st}$ nucleotide) and C to T ($377^{th}$ nucleotide). The nucleotide substitutions at $71^{st}$, $86^{th}$ and $377^{th}$ position of the fragment were found as silent mutations whereas nucleotide changes at $217^{th}$, $258^{th}$ and $371^{st}$ positions were detected as substitution of amino acid lysine with arginine, valine with isoleucine, and leucine with proline from allele A to B. The genotypes had significant effects ($p{\leq}0.05$) on total milk solid%, fat%, SNF%, while showing nonsignificant impact on total protein%. AA genotype produced highest average yield for all the traits.