author(s)
Al-Janabi HRA, Al-Rawi AJ and Al-Anbari NN

abstract
This investigate was conducted at Al Salam Station for dairy cows / Private Sector (Latifia township, 25 km south of Baghdad) for the lactation / 2016 - 2017, in addition the Laboratory of Scientific Progress of Biotechnology and Molecular Genetics Analysis for the period from 1/11/2016 to 1/11/2017. Determination of the genotypes of the LEPR/Thr944Met position of Leptin Receptor gene and the relationship with some of productive and reproductive traits in Holstein cows. The percentages of CC and CT distribution of LEPR were significantly different (P<0.01) in the studied sample, were 84.00 and 16.00%, respectively with allele frequency 0.92 and 0.08 for both C and T respectively. The results of the present study showed that the total milk production of the Holstein cows was significantly affected (P<0.05) by genotype of the LEPR gene and for the cows with the Genotype of CT, while the lactation period was not affected by the genotype of the leptin receptor gene, while the period from birth to peak of production was not significantly affected by the genotype of the LEPR gene, the difference was significant in the length of the peak of production and for the cows with the genotype of CT. The percentage of lipid and non-fat solids were significantly affected (P<0.05) by the genotype of the leptin receptor gene, where the milk of cows with the heterozygous genotype were higher than those homozygous genotype CC, while the percentage of lactose, protein and specific gravity of milk were not significantly affected different genotype of leptin receptor gene. The services per conception was not affected by the genotype of the LEPR gene, whereas cows with homozygous genotype CC have achieved days open (85.76 ±3.78 days) were significantly better (P<0.05) than those with heterozygous genotype CT (95.91 ± 6.00 days). It could be concluded by studying the genotypes of leptin receptor gene that could be adopted in the development of genetic improvement strategies in milk cows to maximize the economic return of their breeding projects by selecting and crossing the genotypes that achieved the best economic characteristics.