Mojtaba Ahani Azari - ۱Vavilov Institute of General Genetics of Russian Academy of Sciences , Laboratory of comparative animal Genetics. Russia ,Moscow & Gorgan, University of Agricultural Sciences and Natural Resourses
Jalal Rostamzadeh - ۱Vavilov Institute of General Genetics of Russian Academy of Sciences , Laboratory of comparative animal Genetics. Russia ,Moscow & ۳Kurdistan University, Sanandaj.
Galina Efimovna Sulimova - ۱Vavilov Institute of General Genetics of Russian Academy of Sciences , Laboratory of comparative animal Genetics. Russia ,Moscow.

The genotypes and allele frequencies for k-casein variants A and B in three herds of Bestoozhevski, Kalmitski and Russian black & white breeds were determined .In this study the size of the screened animals , belonging to studied breeds, were 63 ,91 and 32 respectively. Genomic DNA isolated from blood of animals . The polymerase chain reaction was used to amplify a 228-bp fragment from the K-casein gene. Using PCR-RFLP with two primers SGO and SGE and two restriction endonucleases ( Hinf I and TaqI ), the Distribution of Allele A in these breeds were 0.71, 0.72 and 0.68 and allele B 0.29, 0.28 and 0.32 respectively .The two Alleles A ( Thr136 ,Asp148 ) and B ( Ile136 ,Ala148 ) have a great importance in production traits ,such as milk yield , protein , fat contents and especially cheesemaking properties . because of the important role of the B variant on increasing in milk protein and fat content, as well as cheese production ,it’s effect is known to be economically important , and it is considered to be included in dairy breeding programs .

Kappa-Casein , Hinf I ,Taq I, PCR-RFLP