Impact of FASN Gene Genotypes on Some Milk Components and Udder Dimensions Traits in AWASSI Sheep

Abstract

This experiment was conducted at the Sheep and Goat Research Station located in Al-Shatra District, north of Thi Qar Governorate, affiliated with the Thi Qar Agriculture Directorate. The study lasted from October 11, 2024, to March 26, 2025, and included 40 Awassi ewes.It aimed to study the effect of genotypes of FASN gene on milk components traits, in addition to the udder dimensions characteristics, using Sequencing technology.The field aspect included collecting milk samples and measuring udder dimensions (udder length, udder width, udder circumference, teat length, teat circumference). As for the laboratory part, the proportions of milk components were measured, including (fat, protein, lactose, non-fat solids, density, freezing point, and temperature), and DNA was also analyzed to detect changes in the FASN gene. Sequencing results in the region of exons 37,38 and 39 with a length of 617 base pairs showed no mutations, while the region of exons 18,19 and 20 with a length of 997 base pairs revealed a C>G mutation at position 562 within exon 20, Causing the amino acid to change from Leucine to Valine, this is a type of mutation known as a missense mutation. Three genotypes (CC, CG, GG) were identified with significant differences in their distribution, where the wild type (CC) was the most common (53.1%), and the frequency of the C allele was higher (0.69) than the G allele (0.31). The results showed significant differences in the percentage of milk fats exceeding the GG composition and the density of milk exceeding the CG composition, while no differences were observed in the rest of the components. GG also outperformed udder girth and CG in udder length, with no differences in other traits. It can be concluded from this study that the FASN gene can be used as a genetic marker to improve productive performance in Awassi sheep by selecting genotypes that achieve the best productive performance in milk and its components.