Polymorphism of the β-lactoglobulin gene and its association with milk production traits in Iranian Najdi cattle

The objective of this study was to determine the polymorphism of bovine β-lactoglobulin (β-LG) gene and its association with milk production traits in Iranian Najdi cattle. Blood samples were collected from 80 Najdi cattle from the Najdi cattle breeding station located in Shoshtar, Khuzestan. Polymerase chain reaction (PCR) and restriction fragment length polymorphism (RFLP) techniqus were used for identification of various genotypes. The results indicated that allele frequency of β-LG with regard to the B-allele (0.9125) was higher than that of the A-allele (0.0875). Frequencies of AB and BB genotypes were 0.175 and 0.825, respectively, while the AA genotype was found to be absent. Genotype frequencies were in accordance with the Hardy-Weinberg equilibrium. The effect of β-LG genotypes on milk production traits were analysed using a general linear model (GLM). There was no significant association between different genotypes of β-LG and milk production traits of the analysed cows.