Critical thresholds of BHBA and NEFA for subclinical ketosis and its prevalence prediction in Indian mithun (Bos frontalis) cows demonstrated by ROC analyses.

Indian mithun (Bos frontalis), a rare ruminant species, is exclusively found in northeastern hill region of India and reared under semi-intensive system. Subclinical ketosis (SCK) is caused by an imbalance between energy supply and the needs of cows during lactation. To date, SCK prevalence is not known in mithun and biomarkers for its prediction have not been standardized. The study aimed to establish critical thresholds for serum beta-hydroxybutyrate (BHBA) and non-esterified fatty acids (NEFA) for diagnosis and prevalence prediction of SCK in early-lactation mithun cows. Thirty apparently healthy multiparous (second to sixth lactation) mithun cows (average body weight of 342 ± 45.5 kg) with confirmed pregnancy were selected from two semi-intensive farms. None of the early-lactation mithuns with average milk yield of 1.2 kg/day exhibited signs of any metabolic disease during monitoring period (1, 2, 4 weeks post-partum). Using receiver operating characteristic (ROC) curve analyses, the optimal cut-off point was selected to be ≥ 1.10 mmol/L for BHBA (80% sensitivity, 80% specificity, AUC = 0.9) and ≥ 0.26 mmol/L for NEFA (88.20% sensitivity, 72% specificity, AUC = 0.9). In accordance with cut-off points, mithuns were classified as having SCK and healthy. At 1, 2 and 4 weeks post-partum, 55%, 82% and 64% of the mithun cows had SCK, respectively. There was a significant positive correlation between BHBA and NEFA concentrations (r = 0.78). A rise in serum NEFA and SGOT activity with a concomitant decline in total cholesterol and triglycerides may predict the risk of liver dysfunction associated with SCK. This study is of value in addressing future research on the development of fresh mithun cow programs to prevent SCK and associated liver dysfunction in first 4 weeks post-partum.