[Accuracy of current rapid milk progesterone assays in comparison with a routine laboratory method]

Four current commercially available rapid milk progesterone assays (Cowside rapid tube kit [test No. 1], Hormonost-Schnelltest Milch [test No. 2], Hygia Diagnostic RPT Progesterone Test [test No. 3] and Target-Milch-Progesterone-Schnelltest [test No. 4]) for dairy cows were tested for their accuracy in comparison with the gynecological status on the one hand and by using an approved quantitative laboratory-bound assay on the other hand. Milk samples were taken from 23 dairy cows with behavioural oestrus. From 18 species with expected intermediate levels of progesterone milk probes were taken between day 3 and day 6 post insemination and also from 26 gravid cows. The clinically established gynecological status of the dairy cows correlated completely with their milk progesterone values investigated with the laboratory-bound EIA. In contrast the accuracy levels of the rapid progesterone kits differed. The accuracy of test No. 1 was 81% regarding all milk probes, whereas test No. 2 achieved 91%, test No. 3 73.5% and test No. 4 only 69.5%. Milk samples yielding low progesterone levels partly showed big differences. The highest rates of false semiquantitative classifications were recorded in milk samples with intermediate progesterone values. Test No. 2 was the only one with satisfactory results in this range. Milk samples yielding high progesterone values proved to be the best in all four assays.