Accuracy of INF-tau assay for early pregnancy diagnosis in Awassi ewes compared to progesterone assay and transrectal ultrasonography

The present study evaluated the accuracy of interferon-tau (INF-tau) assay for early pregnancy diagnosis in Awassi ewes compared to progestogen assay and transrectal ultrasonography. Twenty-four non-pregnant Awassi ewes were used in this study. The early pregnancy diagnosis in 22 ewes was evaluated using INF-tau assay, 18 ewes were evaluated using progesterone assay, and 24 ewes were evaluated using transrectal ultrasonography. The accuracy, sensitivity, specificity, and predicted positive and negative values for each method were calculated according to the results of confirmation transabdominal ultrasonography on day 40 of pregnancy. At 15 and 25 days of gestation, the accuracy, sensitivity, specificity, and positive and negative predictive values of INF-tau assay were 77.27, 68.75, 100, 100 and 54.55%, respectively. A significant correlation was observed between the values of INF-tau assay that were recorded at 15 and 25 days of pregnancy. There was a significant correlation between the values of INF-tau and progesterone assay, which were obtained at 25 days of pregnancy. The study results conclude that the INF-tau assay has a good accuracy that can be relied upon as an early pregnancy marker (less than 20 days of pregnancy). However, suppose the duration of pregnancy increases to 25 days or more. In that case, it is preferable to use and depend on transrectal ultrasonography because the INF-tau assay may lead to the culling or slaughter of several pregnant ewes due to incorrect non-pregnant diagnosis.