Serum and Urine Metallotyping of Preketotic and Ketotic Dairy Cows Reveals Major Alterations in Multiple Mineral Elements

Ketotic cows have elevated concentrations of ketone bodies or ketoacids [i.e., β-hydroxybutyric acid (BHBA), acetoacetic acid (AcAc), and acetone (Ac)] in three body fluids including blood, urine, and milk. Both BHBA and AcAc are strong acids, which cause ketoacidosis and affect physiological functions of various tissues. The objectives of the current study were to: 1) investigate mineral alterations in both serum and urine of preketotic, ketotic, and postketotic cows; and 2) identify potential predictive and diagnostic mineral biomarkers for ketosis in serum and urine. Metallotyping was performed in the serum and urine of 6 cases of ketosis and 20 CON cows using inductively coupled plasma mass spectrometry at -8 wks, -4 wks, disease diagnosis wk, +4 wks and +8 wks relative to parturition. Univariate analysis of data was performed using Wilcoxon-Mann-Whitney (rank sum) test provided by R (Statistical significance: P < 0.05). Multivariate data analysis was processed by the MetaboAnalyst software. Results showed disturbances in concentrations of metals in the serum and urine of cows with ketosis at all 5-time points tested. The most important finding of this study was that four trace elements including Al, Fe, Mn, and As were elevated persistently in the serum of preketotic, ketotic, and postketotic cows. Moreover, three minerals (i.e., B, Al, and Rb) were increased in the urine of preketotic (-8 and 4wks prepartum) cows. It is interesting to point out that Al was the most elevated metal in the serum of preketotic cows at -8 and -4 wks prior to parturition at 91.4-fold (120.6 vs 1.32 μM) and 78.12-fold (111.34 vs 1.43 μM), respectively (P < 0.001). Similar alterations for Al were also detected in the urine samples of preketotic (i.e., 0.39 vs 0.05 μM/mM creatinine at -8 wks, P < 0.001; 0.16 vs 0.05 μM/mM creatinine at -4 wks, P < 0.001) cows in comparison with CON ones. Since preketotic and ketotic cows were on a state of chronic metabolic acidosis altered mineral element in both serum and urine are thought to be related to the effects of acidosis on bone metabolism and urine excretion of metals. Findings from the current study might encourage development of early diagnostic biomarkers for risk of ketosis as well as new preventative intervention to lower the risk of ketosis in transition dairy cows.