GENETIC POLYMORPHISM OF MILK PROTEINS IN BARBARI GOATS

Abstract

Milk samples of 178 Barbari goats, maintained at the Central Institute for Research on Goats, Makhdoom, Mathura, Uttar Pradesh, India, were analyzed to study the genetic polymorphisms of milk proteins in this breed. The genetic variants in milk samples were detected by sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS – PAGE) method. The electrophoretic pattern revealed the milk sample of Barbari goats contained four major casein variants, i.e., αS1- casein, αS2 - casein, β-Cn, and κ-Cn and two whey proteins, viz., β- lactoglobulin and α- lactalbumin. Three αS1- casein alleles viz. αS1- CnA, αS1- CnB and αS1-CnF were identified in this study. The predominant allele of αS1- casein was αS1-Cn B, with a frequency of 0.565, whereas the frequencies of αS1-Cn A allele was 0.329. Very low frequency (0.073) of the αS1-CnF variant occurred in the milk of this breed. The frequency of null allele (i.e., absent of this particular allele in the population) for this locus (αS1-Cno) was 0.034. The αS2-locus showed two variants namely A and B and the frequencies of these variants were 0.531 and 0.469, respectively. Two genetic variants (A and B) were also observed in the κ-casein locus having the frequencies of 0.708 and 0.292, respectively. No polymorphism was observed at β- casein locus in our study. The electrophoretic pattern of β- lactoglobulin showed the presence of two genetic variants at β-lactoglobulin (β-LG) locus (viz., A and B) and the gene frequency of β-LG A and β-LG B was 0.910 and 0.090, respectively. Regarding the α-lactalbumin locus, two genetic variants of α-lactalbumin (α -LA) viz., A and B were identified in this breed. The gene frequency of predominant allele i.e, α-LA A allele was 0.966 whereas, the frequency of rare allele i.e., α-LA B was 0.034, respectively.