Polymorphism of κ-Casein Gene in Iranian Holsteins

Background: Genetic polymorphism of milk proteins has been associated with composition, manufacture, and traits of milk. Caseins are the most important milk proteins that its genes are strongly linked and inherited together. κ-casein, which is a quantitatively minor constituent of bovine milk, is thought to play a critical role in organization, fixation and aggregation of casein micelles and firmness of curd during cheese making. Objectives: In this study, we aimed to investigate the polymorphism of κ-casein gene in Iranian Holstein cows. Materials and Methods: In this study, κ-casein gene polymorphism among 50 DNA samples of Iranian Holstein cows via polymerase chain reaction sequence analysis (PCR sequencing) was analyzed. For data analysis SPSS 11.5 (ANOVA test) was used. Results: Four polymorphic sites that created four variants and seven different genotypes of κ -casein gene were identified. In this population the frequencies of A, B, C, and E alleles were as 0.391, 0.413, 0.087, and 0.109 respectively. Conclusions: We suggest that the frequency of κ-casein gene B allele should be increased in Iranian Holsteins because it is an essential factor in marker-assisted selection for milk traits.