Milk Protein Polymorphism in Kangayam Cattle

Abstract

This paper reports the milk protein polymorphism, the allele frequencies of variants and the possible linkages among various combinations of milk protein phenotypes in the Kangayam cattle of south India. Milk samples from 156 Kangayam cows were typed by starch gel and polyacrylamide gel electrophoresis for caseins and whey proteins, respectively. All the four milk protein components studied, α_s1-casein, β-casein, β-lactoglobulin and α-lactalbumin, exhibited polymorphism with high allele frequencies of 0.9231±0.0151 for α_s1-casein C, 0.9263±0.0148 for β-casein A, 0.9135±0.0159 for β-lactoglobulin B and a relatively high frequency of 0.6218±0.0275 for α-lactalbumin A. The mean heterozygosity estimated over all the four milk protein loci was 0.2420. Genetic equilibrium was observed among all the loci studied, except α-lactalbumin. Linkage analysis confirmed the non-independence between α_s1- and β-caseins and between caseins and α-lactalbumin phenotypes.