The Relationship Between Genotype of DRB1 Gene and some Performance Traits of Iraqi Sheep

Abstract

The experiment was conducted at the Sheep and Goat Research Station in Al-Shatrah district located in the north of Thi Qar Governorate, Thi Qar Agriculture Directorate, Ministry of Agriculture, Marshlands Research Center, Thi Qar University. It included 59 animals from the ewes of Iraqi sheep (Awassi), to study the relationship between the genotype of the DRB1 gene and some performance traits in Iraqi sheep, where the study included taking some measurements of body dimensions, taking blood samples for the purpose of laboratory examination of the study, included extraction of genetic material and genetic analysis, using PCR technology at the Marshes Research Center at Thi Qar University. The results of the analysis of the nucleotide sequence sequence of the studied genetic segment of the DRB1 gene showed that the mutation T>G.245 was present in the coding regions of the DRB1 gene, occurred in GTT coding for Valine (V) and changed to GGT coding for the amino acid Glycine (G), located at position (82) in the amino acid sequence of the DRB1 gene, this mutation was located in the region of the second exon, where this mutation was considered a missense mutation. It has three genotypes: TT, TG, and GG, by calculating the allelic frequency, there was a highly significant superiority of the T allele (0.53) over the G allele (0.47) in the T>G mutation.245, the genotypes of the mutation T>G.245 of the DRB1 gene, it was found that there were highly significant differences (P≤0.01) in all characteristics under study, such as birth weight and body dimensions, it was found that the effect of some non-genetic factors on the studied traits, namely, the state of pregnancy, the age of the ewes, and the sequence of childbirth, was highly significant (P≤0.01) in all characteristics of the animal’s body dimensions, except for the width of the breast, it was observed that ewes aged 3-4 years outperformed the rest of the ewes compared to other age groups, was the lowest in sheep less than a year old in all traits under study, the regression coefficient of the characteristics of body dimensions on the weight of the animal were not significant except for the regression coefficient of the rear height of the animal on the weight of the animal. All characteristics of body dimensions (body length, frontal height, posterior height, chest width, and chest circumference) showed a highly significant correlation (P≤0.01), positive and high.