Beta-lactoglobulin candidate gene polymorphism and its association with milk quality traits in Gurez sheep of Jammu and Kashmir

Abstract

Gurez sheep, the largest sheep breed limited to the Gurez valley of Kashmir, are known for sturdiness, adaptability, disease resistance, mutton, and milk production. It produces on average 300-650 ml/day. Beta-lactoglobulin (BLG) a candidate gene affects milk yield and quality. DNA was isolated from 60 Gurez sheep. Milk quality was assessed for fat, SNF, protein, density, and ash for 34 lactating ewes. The BLG gene (Exon II) of size 301 bp was amplified using specific reported primers. The RsaI restriction enzyme revealed genotypes: AA (241/60 bp), AB (241/175/60 bp), and BB (175/60 bp). The dominant genotype was AA, followed by BB and AB, with the A allele showing a higher frequency than the B allele (0.425). The effect of the observed genotypes was non-significant on all the milk quality traits under study, even though the study indicated that the BB genotype was associated with the highest fat (8.50%). The allele substitution effect at the BLG locus was positive on fat (genotype BB by 2.28%) and density (genotype AB by 0.75%). A great diversity in fat % was prevalent in the group under study, thereby evolving possibilities of selection programs in Gurez sheep and harnessing its dairy potential as a good substitute to cow/goat milk.