Marker assistant selection is one of the best methods to improve the accuracy of prediction and response to selection. In studies related to weight gain and meat quality Calpastatin gene has been identified as a candidate gene. This gene is located on cattle chromosome 7 and is effective on formation, lysis of muscle texture and meat tenderness after slaughtering animals. In order to study polymorphism of Calpastatin gene in Holstein cattle 50 animals from Behin Taliseh corporation were randomly sampled. DNA extraction was carried out by modified salting out method. Polymerase chain reaction was performed to amplify a 622bp fragment of the L region of exon and entron 1 of this gene. Restriction reaction of PCR products was done using MspI enzyme. Then all the animals were genotyped base on digested fragment profile, respectively. Frequencies of MM, MN and NN genotypes were 46%, 54% and 0% for Holstein cattle and 0%, 45% and 55% for Buffalo. Frequencies of M and N alleles were 0.73 and 0.27, respectively for Holstein cattle and 0.225 and 0.775 for Buffalo. Results showed that this locus was not at Hardy–Weinberg equilibrium in the Holstein cattle (P<0.05) while Buffalo herd showed equilibrium.

Genotypes of Iranian Zel sheep for Calpastatin (CAST) locus were determined by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) and polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP) methods and for Calpain (CAPN) locus by PCR-SSCP. Blood samples were collected from 200 purebred Zel sheep of Zel Breeding Station located in Golestan province in northeast of Iran. Extraction of genomic DNA was based on modified salting out method. The digestion of PCR products of CAST gene by MspI and NcoI restriction enzymes revealed two alleles M and N, with frequencies 85.5 and 14.5%, respectively. Frequencies were 75, 21 and 4% for MM, MN and NN genotypes, respectively. Alternatively, using PCR-SSCP method, four genotypes including AA, AB, BB and AC with frequencies of 71, 21, 4 and 4%, respectively, were observed in this population. Analyzing CAPN gene by the PCR-SSCP method, revealed two different conformational patterns (AA and AB) with frequencies of 69 and 31% for AA and AB, respectively. Average heterozygosity for both loci was low (0.28 and 0.25% for CAST using PCR-SSCP and PCR-RFLP, and 0.26% for CAPN). Yearling weights (YW) were analyzed by a statistical model comprising PCR-SSCP and as a result CAPN genotypes had significant effect (P<0.01) on YW. A Chi-square test confirmed Hardy-Weinberg (H-W) equilibrium for the CAST locus using PCRSSCP method but not for PRC-RFLP method and CAPN locus. Totally, the investigated herd had little genetic diversity and different factors disturb H-W equilibrium and PCR-RFLP and PCR-SSCP might be used successfully in these studies.

In this research for studying genetic polymorphism of κ-casein (CSN3) and growth hormone (GH) genes as candidate genes for marker-assisted selection in different domestic livestock species, blood samples (120 samples) were collected from Dalagh sheep randomly. DNA was extracted from blood samples and a 416 bp fragment from exon 4 of the CSN3 gene and a 365 bp region from exon 5 of the GH gene were amplificated by polymerase chain reaction. PCR products were analyzed using single strand conformation polymorphism (SSCP) method on a polyacrilamide gel. Results indicate that there are two (K1=0.92 and K2=0.08) and three (G1=0.84, G2=0.13 and G3=0.03) conformational patterns for CSN3 and GH genes, respectively.

Calpains play a major role in post mortem tenderization and calpastatin is the endogenous inhibitor of calpain proteases and regulates the rate and extent of post mortem tenderization. Myostatin is an inhibitor of skeletal muscle growth and a mutation in the gene coding region leads to increased muscling. Therefore, they are considered as candidate genes for meat and growth traits. Blood samples were collected from 110 Dalagh sheep and DNA were extracted using modified salting out extraction method. Genotypes were determined by PCR amplification followed by single-strand conformation polymorphism (SSCP) method for calpain gene and restriction fragment length polymorphism (RFLP) method for calpastatin and myostatin genes. Based on results, calpastatin and calpain genes were found to be polymorphic but myostatin gene was monomorphic. Genotype frequencies were 36, 38, and 26 % for MM, MN and NN in calpastatin locus, respectively. In this population, calpastatin locus did not show Hardy-Weinberg equilibrium (P<0.05). Observed heterozygosity for this locus was good (0.38). Under the SSCP analysis, three different patterns (G1 , G2 and G3 ) with frequencies of 8.2, 89.1, and 2.7 % were detected in calpain locus, respectively. Detected polymorphisms and assumed associations of genetic variation with meat production and tenderness may help to find the effective genotypes of Dalagh sheep for those economic traits.