Effect of hyperketonemia on the diurnal patterns of energy-related blood metabolites in early-lactation dairy cows

Most dairy cows experience a period of energy deficit in early lactation, resulting increased plasma concentrations nonesterified fatty acids (NEFA) and β-hydroxybutyrate (BHB). Our objectives were to determine (1) the diurnal variation BHB NEFA, (2) correlation between NEFA when accounting for changes, (3) effect hyperketonemia (HYK) on pattern blood metabolites. Jugular catheters placed 28 multiparous Holstein 3 9 days milk, samples collected every 2 h 96 h. Cows retrospectively classified as HYK positive (HYK; n = 13) if they had ≥1.2 mmol/L ≥3 study days, or negative (non-HYK; 15) ≤2 days. Generalized linear mixed models used analyze analytes over time differences metabolites groups. The total was analyzed by calculating area under curve all cows. Plasma reached peak approximately before morning feed delivery, falling nadir late evening. at peaking 4 later. We observed strong daily BHB. Additionally, greater than non-HYK also experienced magnitude change throughout day results suggest that relative feeding should be considered analyzing metabolites, classification status may day.