Evaluation of an electronic cowside test to detect subclinical ketosis in dairy cows

Abstract

The objective of this study was to determine the diagnostic performance of an electronic beta-hydroxybutyrate (BHBA) hand-held meter (Precision Xtra) for use in dairy cattle. Specific objectives were to compare the electronic BHBA meter with serum BHBA concentrations determined photometrically and 2 commonly used chemical cowside tests (Ketostix, Ketolac) and to evaluate accuracy in a field study employing 35 investigators. Of the 196 blood samples collected in experiment 1, 17 (8.7%) contained > or =1,200 micromol of BHBA/L of blood and 10 (5.1%) contained > or =1,400 micromol of BHBA/L of blood. Pearson correlation coefficients were highly significant for all tests. The highest correlation coefficient (0.95) was found between measurements of whole blood BHBA determined with the Precision Xtra test and the serum BHBA concentrations determined photometrically. Correlation coefficients between serum BHBA and BHBA in urine using Precision Xtra and Ketostix, and milk using Ketolac were lower. The Precision Xtra test was both 100% sensitive and specific at > or =1,400 micromol of BHBA/L of whole blood. Using milk and urine, positive and negative predictive values were considerably lower for both chemical tests as well as for the electronic meter. In the second study undertaken with 35 bovine veterinary practices, 926 blood samples were collected. In this study, the Precision Xtra test had sensitivities of 88 and 96% at 1,200 and 1,400 micromol of BHBA/L of whole blood, respectively. Specificities were 96 and 97%, respectively. Level of agreement was lower in the second study employing multiple investigators. Considerable differences in variance occurred among investigators. We conclude that the electronic hand-held BHBA measuring system using whole blood is a useful and practical tool to diagnose subclinical ketosis. Sensitivity and specificity are excellent for a cowside test and higher than 2 commonly used chemical dipsticks (Ketostix and Ketolac).

Evaluation of a Hand-Held Meter to Detect Subclinical Ketosis in Dairy Cows

“…The correlation coefficient between the BHBA values obtained from the laboratory method compared to those obtained from the hand-held meter was 0.98 indicating that the hand-held method of testing SCK was as effective and accurate as the laboratory method. The results were in agreement with the findings of other researchers who reported that the coefficient of correlation between the laboratory methods and a hand-held meter in measuring plasma concentration for BHBA varied from 0.92 to 0.97 [2,21,26]. The agreement between the two methods was good since the bias was -0.02 which was lower than 0.036 reported by Voyvoda and Erdogan [2].…”

“…The proportion of cows diagnosed with SCK was lower in this study compared to others [2,16,21,23] which showed that SCK was not a serious problem in the farms studied.…”

“…Measuring serum concentration of BHBA is useful for examining individual cows, evaluating herd health and monitoring feeding management [21]. However, the quantitative determination of BHBA depends on special laboratory equipment and requires blood sampling, centrifugation, freezing of plasma or serum samples, and shipping of frozen samples to the laboratory [21]. These methods are thus neither convenient nor costeffective for routine cowside diagnostic test in early detection of SCK [2].…”

“…Few studies have shown that hand-held meters are useful in detecting subclinical ketosis of dairy cows [21,2]. Therefore, the objective of this study was to evaluate the performance of a new hand-held meter (TNN, Yicheng, Beijing,China) which is used to diagnose SCK in dairy cows by comparing its accuracy with laboratory methods for determining BHBA concentration in blood, milk and urine samples.…”

“…Threshold values of either 1.2 mmol/L [19,20] or 1.4 mmol/L [6,12,16,17] of BHBA in serum or plasma have been recommended to distinguish between normal and cows suffering from SCK. Measuring serum concentration of BHBA is useful for examining individual cows, evaluating herd health and monitoring feeding management [21]. However, the quantitative determination of BHBA depends on special laboratory equipment and requires blood sampling, centrifugation, freezing of plasma or serum samples, and shipping of frozen samples to the laboratory [21].…”