Calpastatin plays an essential role in the growth of skeletal muscles and post mortem meat tenderness. The objective of this research was to determine polymorphism in the calpastatin gene in a group of 212 sheep (192 ewes and 20 rams) of four breeds: Polish Merino, Berrichon du Cher, Blackheaded Mutton Sheep, and Ile de France. Polymorphism was identified using the PCR -RFLP technique in accordance with methods by Palmer et al. [9]. The amplified product with the length of 622 bp was digested with restriction enzymes MspI and NcoI. It was found that the M and N alleles were present in CA ST/MspI locus, their frequency being 83.5% and 16.5% respectively. Whereas in CA ST/NcoI locus the M allele occurred with the frequency of 95.8%, and the N allele with the frequency of 4.2%.
