Abstract

Heat stress poses a significant challenge to dairy cattle, affecting their overall health and productivity. This study investigates the impact of heat stress on amino acid metabolism in Holstein dairy cows using plasma and milk metabolomics. Twelve lactating Holstein cows were subjected to heat stress conditions, and plasma and milk samples were collected before and during heat stress exposure. Metabolomic analysis revealed significant alterations in amino acid profiles in both plasma and milk samples under heat stress conditions. Several essential and non-essential amino acids exhibited changes in concentration, indicating disruptions in amino acid metabolism pathways. Specifically, increased levels of certain amino acids, such as glutamate and aspartate, were observed in plasma and milk samples during heat stress, suggesting enhanced protein catabolism and gluconeogenesis. These findings provide valuable insights into the metabolic response of dairy cows to heat stress and highlight the importance of amino acid metabolism in maintaining metabolic homeostasis during thermal stress. Understanding the mechanisms underlying these metabolic alterations may inform strategies for mitigating the negative effects of heat stress on dairy cow health and productivity.