Genetic polymorphism of the beta-lactoglobulin gene in native sheep from India

The genetic polymorphism of the beta-lactoglobulin (beta-LG) gene was determined in 638 animals belonging to 15 native Indian sheep breeds reared in different agroecological regions for various production traits. Variants of beta-LG were found using PCR-RFLP of genomic DNA. Rsa1 restriction enzyme digestion of a 120-bp PCR fragment of exon 2 of beta-LG revealed two genetic variants, A (0.37) and B (0.63), and the three genotypes AA (0.175), AB (0.389), and BB (0.436). The differences in allelic frequency were not significant across the breeds, irrespective of their geographic origin and utility (chi(2) test, P > 0.05). The pattern of occurrence of allelic variants revealed that the B allele was more frequent in the majority of the Indian breeds than in breeds reported from countries of Southwest Asia, Eastern and Central Europe, and the Mediterranean. A higher level of heterozygosity (0.422) was discerned, despite the declining status of several of the Indian breeds. These findings revealed that Indian sheep are predominantly of the beta-LG B type.