Abstract

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 (71st nucleotide), C to
T (86th nucleotide), A to T (217th nucleotide), G to A (258th nucleotide), A to C (371st nucleotide) and C to T (377th nucleotide). The
nucleotide substitutions at 71st, 86th and 377th position of the fragment were found as silent mutations whereas nucleotide changes at
217th, 258th and 371st 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??.05) on total milk solid%, fat%, SNF%, while showing nonsignificant
impact on total protein%. AA genotype produced highest average yield for all the traits.