Milk protein polymorphism in Kangayam cattle.

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, alpha(s)1-casein. beta-casein, beta-lactoglobulin and alpha-lactalbumin, exhibited polymorphism with high allele frequencies of 0.9231 +/- 0.0151 for alpha(s)1-casein C, 0.9263 +/- 0.0148 for beta-casein A, 0.9135 +/- 0.0159 for beta-lactoglobulin B and a relatively high frequency of 0.6218 +/- 0.0275 for alpha-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 alpha-lactalbumin. Linkage analysis confirmed the non-independence between alpha(s)1- and beta-caseins and between caseins and alpha-lactalbumin phenotypes.