The ovine melatonin receptor 1A (MTNR1A) and aromatase (CYP19) genes were structurally characterized and the association between their variants and reproductive and growth traits was studied in Kurdi sheep at Kurdi sheep breeding station located in Shirvan, Iran. The genomic DNA was extracted by guanidine thiocyanate-silica gel method. Polymerase chain reaction was carried out to amplify 824 bp fragment of exon 2 of MTNR1A and 140 bp fragment of the exon 3 of the ovine CYP19 genes. The PCR products were digested with restriction endonucleases RsaI for MTNR1A and BstMBI for CYP19 genes and checked by polyacrylamide gel electrophoresis for the presence of restriction sites. Two alleles were found for all the loci investigated, which were named as A and B for CYP19, and R and r for MTRN1A. Allelic frequencies for MTRN1A were 0.49 and 0.51 for R and r alleles, while in the case of CYP19 gene, frequencies were 0.475 and 0.525for A and B alleles, respectively. Association analysis did not show any significant relations between MTNR1A gene polymorphisms and litter size (LS), age at first lambing (AFL) and lambing interval (LI). Moreover, CYP19 gene polymorphism did not affect birth weight (BW), weaning weight (WW), 6, 9 and 12 months (YW) body weights, age at first lambing (AFL) and lambing interval (LI). تفاصيل المقالة

CSN1S1is one of the major genes encoding milk proteins of mammals. In this study we determined allele frequencies of CSN1S1-5` flanking region as well as exon 17 variants and their effects on milk traits in three indigenous cattle breeds Mazandarani, Golpaygani (Bos indicus) and Sarabi (Bos taurus) and Holstein cattle in Iran. CSN1S1*B variant was nearly fixed in Holstein but ranged from 0.40 to 0.66 in indigenous breeds. CSN1S1*C allele had higher frequency inindigenous breeds, especially inBos indicus. Four genetic variants of the promoter were found in all breeds in different frequencies with allele 2 being the prevalent in all breeds (frequency 0.359 to 0.711) and allele 4 the least frequent (0.074 to 0.011). Allele B of the coding region was found in combination with all four promoter alleles. Allele 4 of the promoter was not found in any cow having the exon 17 allele C in all breeds except Mazandarani. BC / 23 genotype yielded the highest fat percentage (P<0.05) in Holstein but it had no significant effect in Golpaygani. There was not any homozygous CSN1S1*CC cow, to investigate the influence of C variant for fat content. None of the genetic combinations had significant effect on fat yield, although variant '2' of promoter indicated a negative effect. No significant effect among various combined genotypes on milk yield was found, but CSN1S1*B tended to higher milk production. Differences of allelic frequencies and milk production traits found among these breeds might be due to differences in origin of breeds or selection breeding programs. تفاصيل المقالة