Liver metabolic perturbations of heat-stressed lactating dairy cows

OBJECTIVE: The objective of the present study was to elucidate the mechanism underlying liver metabolic perturbations in dairy cows exposed to heat stress (HS). METHODS: Liquid chromatography massabl spectrometry was used to analyze metabolic differences in livers of 20 dairy cows, with and without exposure to HS. RESULTS: The results revealed 33 potential metabolite candidate biomarkers for the detection of HS in dairy cows. Fifteen of these metabolites (glucose, lactate, pyruvate, acetoacetate, β-hydroxybutyrate, fumaric acid, citric acid, choline, glycine, proline, isoleucine, leucine, urea, creatinine, and orotic acid) were previously found to be potential biomarkers of HS in plasma or milk, discriminating dairy cows with and without HS. CONCLUSION: All the potential diagnostic biomarkers were involved in glycolysis, amino acid, ketone, tricarboxylic acid, or nucleotide metabolism, indicating that HS mainly affected energy and nucleotide metabolism in lactating dairy cows.