The effect of β-Lactoglobulin gene polymorphism on the breeding value of milk production trait in Brown Swiss cattles

The β-lactoglobulin gene (β-LG) has been considered to be one of the most important genes involved in the milk productin related traits. In the present research, the association of β-LG polymorphism with breeding values for milk production related traits was investigated in Brown Swiss cattle. The data of this study was collected from the Golpayegan dairy farm. In this study, genomic DNA was extracted from 150 blood samples by modified salting out method. Following this stage, a fragment of 247 bp was amplified and used for enzymatic digestion. The HaeIII restriction enzyme was used to digest of 247 bp of gene. The results showed that genotypes AA, AB and BB of the β-LG gene were estimated to have frequencies of 0.24, 0.48 and 0.28, respectively. These Genotypes were distributed according to the Hardy-Weinberg equilibrium.Genetic parameters were estimated by the restricted maximum likelihood (REML) method using DFREML program. Heritability and repeatability for milk yield traits were estimated to be 0.154 and 0.309, respectively. The statistical analysis based on the General Liner Models revealed that there is no significant effect for β-LG genotypes on the milk yield breeding values.