Comparative study on different field tests of ketosis using blood, milk, and urine in dairy cattle

This study assessed the diagnostic performance of five field tests for ketosis in the blood, milk and urine in dairy cows. Samples were collected simultaneously from 102 dairy cows to determine the accuracy of the test results. The concentration of β-hydroxybutyrate (BHBA) in the blood was measured quantitatively by using a portable ketone test kit. The milk and urine samples were analysed semi-quantitatively using different commercial test kits and urine sticks. The animals were categorised into a subclinical ketosis (SCK) and clinical ketosis (CK) group based on the BHBA concentration in the blood. The diagnostic performance of the milk and urine test kits was compared with the blood test kit. In the blood test, out of 102 cows, 27 and 19 cows were diagnosed with SCK and CK, respectively. The percentage agreement (kappa value) for the three different milk tests and the urine test kit was 43% (κ = -0.181), 72% (κ = 0.243), 63% (κ = 0.065) and 64% (κ = 0.163), respectively, for the SCK detection, which indicates lower sensitivity. However, a strong agreement with 88% (κ = 0.612), 85% (κ = 0.505), 86% (κ = 0.528) and 91% (κ = 0.753) was observed in the three milk tests and the urine test, respectively, for the CK diagnosis, showing a higher sensitivity. For the diagnosis of the SCK and CK, all the tested kits are generally applicable for the detection of CK in dairy cattle, but caution is needed during the interpretation of the SCK data due to the low sensitivity of the milk and urine tests for the SCK detection. Furthermore, this study suggests that milk and urine samples can be used as alternatives for the diagnosis of CK in replacement of blood tests.