Genetic Polymorphism of Milk Proteins

Abstract

Extensive studies on the qualitative and quantitative aspects of milk proteins in more than 100 mammalian species have demonstrated that the protein content varies from 1 to 20% between different species and within the same species of different genetic backgrounds under different environmental conditions. The milk of all species so far analysed contains an acid- precipitable fraction, commonly known as casein, and an acid-soluble fraction known as the whey protein or milk serum protein. Gel electrophoretic techniques have been used to reveal the identity of several types of caseins and whey proteins and to establish the presence of homologous proteins across several species. The discovery of two electrophoretically distinct forms of β-lactoglobulin by Aschaffenburg and Drewry (1955) initiated very active research in the field of genetic polymorphism of milk proteins in several countries around the world. Research activity from different teams has contributed significantly to knowledge on the biochemistry, molecular and population genetics, properties of milk proteins and their associations with production traits.