Comparison of a lateral flow milk progesterone test with enzyme immunoassay as an aid for reproductive status determination in cows.

The lateral flow test (LFT) is an immunochromatographic method that utilises an immunostrip for non-laboratory diagnostic purposes. The present study evaluated a milk progesterone LFT against the enzyme immunoassay (EIA) to confirm oestrus and a non-pregnancy diagnosis. In total, 277 milk samples from 70 cows were analysed, collected on the day of artificial insemination and at 19 days, 21 days and 24 days post insemination. The level of accuracy of the LFT compared with the EIA was 95.0 per cent for milk samples containing <2 ng/ml progesterone and 97.0 per cent for milk samples containing >10 ng/ml progesterone. The validation of oestrus by the LFT was 98.6 per cent accurate using 2 ng/ml progesterone as the EIA estimate for oestrus. The test performance for a non-pregnancy diagnosis was subject to the day of milk sampling, showing the highest accuracy on day 24 post insemination for both tests. When optimised for maximum specificity, and compared with rectal palpation, the LFT had a sensitivity and specificity for non-pregnancy diagnosis on day 24 post insemination of 75.0 per cent and 100.0 per cent, respectively, with an overall accuracy of 84.4 per cent. The corresponding characteristics for the quantitative EIA were 85.0 per cent, 100.0 per cent and 90.6 per cent, respectively. The LFT results compared favourably with the quantitative milk progesterone EIA.