Polymorphism of CAST gene in five sheep breeds in Bulgaria

CAST gene is a candidate marker that influences the intensity of growth and meat quality. The aim of this study was to investigate the genetic variability of CAST gene in five Bulgarian sheep breeds – two merino, two local and one for milk. A total of 150 ewes, belonging to these breeds were investigated for polymorphisms of CAST gene by using PCR-RFLP method. A 622 bp fragment of Ovis aries CAST gene was amplified using PCR. After restriction with endonuclease MspI two alleles were observed in Ascanian, Caucasian, Breznik and Pleven Blackhead breeds. One allele (M) and one genotype (MM) were detected in Cooper-Red Shumen breed. The highest frequency of the allele N was established in the Ascanian merino breed (0.27) followed by Caucasian merino (0.13), Breznik (0.12) and Pleven Blackhead (0.07). Two genotypes - MM and MN, were observed in Caucasian, Breznik and Pleven Blackhead breeds. The three possible genotypes were found only in Ascanian merino ewes - MM, MN and NN. The lowest frequency of the homozygous genotype MM (0.50) and the highest frequency of the heterozygous genotype MN was established in the Ascanian merino breed (0.47). The obtained results confirm that the PCR-RFLP method can be used to identify different genotypic variation of CAST gene in Bulgarian sheep breeds. The established genetic diversity in the calpastatin gene indicates that, after further associative studies, this gene may be included in the breeding programs of certain sheep breeds