Effect of polymorphic variants of growth hormone (GH), β lactoglobulin (β LG), and Pit 1 genes on milk yield was analyzed in a Holstein herd. Genotypes of the cows for these genes were determined by polymerase chain reaction restriction fragment length polymorphism (PCR RFLP) method. Allele frequen cies were 0.884 and 0.116 for L and V variants of GH, 0.170 and 0.830 for A and B variants of Pit 1, and 0.529 and 0.471 for A and B variants of β LG, respectively. GLM procedure of SAS software was used to test the effects of these genes on milk yield. Results indicated significant effects of these genes on milk yield (P < 0.05). Cows with LL genotype of GH produced more milk than cows with LV genotype (P < 0.05). Also, for Pit 1 gene, animals with AB genotype produced more milk than BB genotype (P < 0.05). In the case of β LG gene, milk yield of animals with AA genotype was more than BB genotype (P < 0.01). Therefore, it might be concluded that homozygote genotypes of GH (LL) and β LG (AA) were superior compared to heterozygote genotypes, whereas, the heterozygote genotype of Pit 1 gene (AB) was desirable.

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It was concluded that natural extracts increase the IVD competence of oocytes. The improved effect on oocyte maturation was dependent on the addition of optimum concentrations of extract to the maturation medium.

The aim of present study was to investigate myostatin gene polymorphism and its association with yearling weight records in Zel sheep using PCR-RFLP and PCR-SSCP methods. Blood samples were collected from 200 Zel sheep, randomly, and DNA was extracted using modified salting out method. Polymerase chain reaction was carried out to amplify 337, 222, and 311 bp fragments, respectively, comprising a part of exon 3, intron 1, and intron 2 of myostatin gene. In addition, exon 3 was digested by HaeIII enzyme under RFLP method, and introns 1 and 2 were studied using SSCP. Under RFLP method, all samples showed mm genotype. Under SSCP method, intron 1 was also monomorph but intron 2 was polymorph (AA, AB, and BB). The allelic frequencies for A and B were 75.5 and 24.5%, respectively. This locus was not in Hardy-Weinberg equilibrium (P < 0.05), and there was no significant effect of myostatin gene on yearling weights.