Genome-wide association studies of economically important traits in Holstein cattle under thermal load conditions (review)

Abstract

Global climate change, accompanied by extreme weather events, has a negative impact on livestock farming. A pressing issue is heat stress in dairy cattle, which leads to reduced productivity, fertility, and deterioration of animal health. In this regard, interest in studying the genetic mechanisms of adaptation in cattle to high temperatures is growing. The Holstein breed, being the most widespread in global dairy farming, is widely imported into various countries, including Russia. However, intensive selection for milk production has led to a decline in adaptive traits and increased sensitivity to heat stress. Consequently, genome-wide association studies (GWAS) are becoming a key tool for identifying candidate genes associated with economically important traits in cows under thermal load conditions. Analysis of the studies conducted in different countries has highlighted the genes related to productivity, fertility, physiological parameters, and health under high-temperature conditions. Among the most significant genes associated with milk production are DGAT1, HSF1 and GHR. In China and Mexico, where heat stress is especially pronounced, candidate genes such as SPAG17, FAM107B, PMAIP1 (physiological indicators) and AMH, IGFBP1 (reproductive capacity) have been identified. Today, many countries around the world are experiencing an increase in the number of days with abnormally high temperatures, which necessitates a comprehensive study of heat tolerance in farm animals using population genetics methods. Genome-wide association studies allow not only for the identification of the genes explaining the variability of economically important traits under heat load but also for the development of genomic selection strategies to form herds resilient to climate change.