POLYMORPHISM OF COI GENE AND ITS ASSOCIATION WITH MILK PRODUCTION AND LAMB?S GROWTH BEFORE WEANING OF IRAQI AWASSI SHEEP

This study was conducted in the Laboratory of Genetic Engineering/ College of Agriculture/ University of Basra. It aimed at measuring the genetic polymorphism of COI within the mitochondria of Awassi sheep and its relation to milk production and therefore the growth of lambs till weaning. Data were collected from eighty-seven ewes with their lambs (87 lambs). Milk and blood samples were collected from ewes. Body weight of lambs at birth and each 15 days until weaning also included. Milk samples were collected every 2 weeks till the age of weaning. DNA was extracted from the blood and the polymerase Chain Reaction (PCR) technique was used to amplify the COI gene. After that the amplification product was purified and samples were analyzed by the Korean Macrogene Company for DNA sequencing analysis. The Alignment sequences were aligned with the standard sequences published within the National Biosciences information Centre (NCBI) using the BioEdit program. The genetic polymorphism, haplotype and nucleotide diversity were estimated using Dnasp v5.10 program. The genetic distance, molecular variation AMOVA and neutral test by Arlequin ver. 3.5.1.2. The haplotype network was determined by the net 5.0.0.0 program. The tree of evolution was developed using MEGA 7.0. COI gene showed the presence of a thirteen genetic polymorphism in the breed of Awassi sheep. The diversity of the haplotype (HD) and therefore the nucleotides (π) of this gene was high (0.852, 0.00391 respectively). The total number of haplotypes (H) was nine. The number of haplogroup of COI factor was 3. While the genetics and evolution tree of COI showed that there were 3 main branches when compared with sheep breeds of different countries. Awassi sheep breed appeared in a separate branch from the other breeds of these countries. The results of the AMOVA showed that the variation within the breeds is a lot of bigger than the variation between breeds (13.52% vs 86.48%). The results of the neutrality test exhibited negative values, which indicate AN enlargement of the Iraqi Awassi sheep breed. The overall average milk production, birth weight and weaning weight (522.99 g, 4.52 kg and 17.73 kg respectively) were non-significantly associated with COI. However, COI polymorphism associated significantly weaning weight. Therefore, COI can be used as a genetic marker to genetically improve weaning weight in this breed since it showed high genetic variation among individuals (within the breed).