Molecular biology techniques genetic improvement by facilitating identification, mapping and analysis of polymorphism of genes by encoding proteins that act on metabolic pathways involved in economically interesting traits. This use of genetic markers can aid identification of those animals with the highest breeding values in sheep. On the basis of sheep genome mapping, information was examined on the ovine IGF1 and PIT1 genes as a possible genetic marker for growth traits in sheep. The current study was designed to estimate the frequencies of putative IGF-1 and PIT-1 genes SNPs and investigate associations with calculated EBVs of growth traits in Makooei sheep. PCR-SSCP analysis of the exon1 of IGF-I gene and include a part of intron2, exon3 and a part of intron3 and PIT-1 gene revealed the following banding patterns; three (AA, AG, GG) and four AA (p1), AB (p2), CC (p3), CD (p4), banding patterns respectively. Results from this study demonstrated higher performance of AA animals in BW and GBW, and AG animal in WW and W6 that may be related to the role of IGF-1 at the pre-puberty and puberty stages. Also higher performance of p3 animals in W9, YW and GSN, and p1 animal in GNY may be related to the PIT-1 role in post-puberty.

The research was undertaken to find association of genetic variation in the exon 3 of the leptin gene and breeding value of body weight traits in Makooei sheep breed using single strand conformation polymorphism (SSCP). The PCR product was obtained to encompass exon 3 of leptin gene corresponding to ovine leptin gene. The PCR fragments were subjected to electrophoresis to reveal the SSCP patterns. Among the total of 130 sheep, five SSCP patterns (haplotypes) were identified for amplified fragment. The frequencies of SSCP patterns of polymorphic fragment were 0.09, 0.17, 0.37, 0.14 and 0.23.The relation between the different haplotypes and body measurements including body length (BL), heart girth (HG), height at withers (HW), height at back (HB), rump length (RL) and scrotal circumference (SC) were ascertained in all of the analyzed animals. According to our results, there is significant association between the different haplotypes of this fragment with additive estimated breeding value for the HG and RL traits. These results confirmed the potential usefulness of leptin gene in marker-assisted selection programs for sheep breeding in Makooei sheep breed.

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