Comparison of electronic nose and conventional cow-side diagnostic tools for detection of ketosis in early lactation dairy cows
Keywords:ketosis, dairy cattle, diagnostic test, electronic nose
Rapid diagnosis of ketosis in dairy cows is imperative for treatment and managing economic losses. Cow-side ketosis diagnostic tools are greatly needed. The objective of this study was to compare three tools for the detection of ketosis, using serum β-hydroxybutyrate (BHB) as the gold standard. The diagnostic tools tested were: (1) Precision Xtra® handheld blood ketone meter, (2) ReliOn® urine ketone test strip, and (3) Cyranose 320® electronic nose (eNose) for use on milk and urine. Dairy cows (n = 60) were sampled immediately post-calving. Whole blood, serum, milk, and urine were collected and analyzed on the same day. Each modality was compared to BHB to determine sensitivity and specificity. Positive predictive value (PPV) and negative predictive value (NPV) were calculated across a range of ketosis, consistent with reported prevalence (10-35%) in U.S. dairy operations. Urine ketone strips provided the highest specificity (99.2%), yet low sensitivity (58.6%). The Precision Xtra demonstrated adequate sensitivity (93.8%) and specificity (92.9%). The eNose had substandard sensitivity and specificity when used on milk (Sn: 58.8%; Sp: 44.3%) and urine (Sn: 18.8%%; Sp: 80.6%) compared to the other modalities. Although the actual predictive values change with prevalence, urine ketone test strips had the highest PPV (89.5-97.6%) and Precision Xtra had the highest NPV (99.3-96.5%) across all simulated ketosis prevalences. Both urine ketone test strips and the Precision Xtra are adequate cow-side ketosis detection tools. Further optimization of the eNose is needed before deployment as a field diagnostic tool.