Calpastatin, a specific inhibitor of the calpains, participates in muscle growth and tenderization. Amplified fragment of 12 intron of CAST was used; the gene encoding calpastatin, from 164 lambs from synthetic lines for restriction fragment length polymorphism analysis. Although, CAST has previously been investigated in sheep, the observed polymorphism incidence in this population was higher. Furthermore, three previously identified alleles as well as one new allelic variant (allele “e”) have been detected. Eight genotypes were observed in this population. The results of this study may be useful in further research supporting associations between polymorphism in the ovine CAST gene on both the function and expression gene.

Key words: Polymorphism, sheep, calpastatin, RFLP, meat quality.