Effect of beta lactoglobulin polymorphism on milk production in Holstein dairy cattle of Iran

Abstract

Beta-Lacto globulin (BLG) is a major protein in the milk of ruminants. Bovine BLG gene is located on the chromosome 11q28 and has two common genetic variants, ‘A’ and ‘B’ (Gene-Bank X14710). These variants are different in amino acids at positions 64 and 118, where allele ‘A’ has Asp and Val and allele ‘B’ has Gly and Ala, respectively. Difference at position 118 can be detected by PCR-RFLP (Medrano and Agiular-Cordova 1990). It is reported that allele ‘A’ is associated with milk production (Strzalkowska et al. 2002) and allele ‘B’ has a positive effect on fat percentage (Tsiaras et al. 2005). The aim of our study was to estimate the allelic frequency in polymorphic site of exon IV (allele ‘A’ or HaeIII (-)) of BLG gene in Holstein dairy cattle of Iran and also to find any association of total milk production (first lactation) with BLG genotypes.