Determination of the relationships between parameters associated with heat stress tolerance and some candidate genes in ile de France x Anatolian merino crossbred sheep

Climate change represents one of the most significant challenges ever faced by humanity, threatening both global ecological balance and economic security. The stress induced by rising temperatures due to global climate change not only leads to reduced productivity in livestock but also adversely affects reproductive performance and overall animal welfare. These impacts result in substantial economic losses for breeders and pose a serious threat to the sustainability of the global food supply. As environmental temperatures are expected to rise further in the near future, it is crucial to identify animals with high tolerance to thermal stress, quantify their prevalence within the population, and establish suitable breeding systems and nutritional programs to ensure sustainable livestock production.In this context, the present master's thesis aimed to identify polymorphisms in the HSP, PRL, STAT, and JAK genes in Ile de France × Anatolian Merino crossbred (IFAM) sheep a genotype widely preferred by breeders in the Eskişehir province and to investigate the associations between these polymorphisms and thermo-physiological traits. For this purpose, polymorphisms at 11 loci on the HSP, PRL, STAT, and JAK genes were identified using various molecular techniques in 179 IFAM sheep, and their associations with thermo-physiological traits such as rectal temperature (RT), respiratory rate (RR), mean body temperature (MBT), and heart rate (HR) were investigated. The analysis revealed that, within the PRL (P1-23 bc ins.) gene region, sheep carrying the DD genotype had significantly lower HR compared to those with II and ID genotypes. Additionally, in the JAK1 (indel4) gene region, sheep with II and ID genotypes exhibited significantly lower RT than those carrying the DD genotype. These findings suggest that the PRL (P1-23 bc ins.) and JAK1 (indel4) gene regions may serve as potential candidate markers in marker-assisted selection (MAS) programs aimed at improving heat tolerance in IFAM sheep.