Evaluation of Ultrasound for Pregnancy Diagnosis Between 20 and 40 Days Post Insemination in Dairy Cows

A study to evaluate the accuracy of pregnancy diagnosis in dairy cows was conducted using animals between 20 and 40 days after service. The accuracy of the method was obtained calculating the sensitivity, specificity, positive and negative predictive values (PPV and NPV). The highest values in these indicators were obtain between 31-35 and 36-40 days post insemination, with a NPV of 97% for both ranges and a sensitivity of 98 and 97%, respectively. The PPV and the specificity for both ranges was 85.7 and 93.6% and 80 and 93%, respectively. The decrease of the PPV and specificity could be affected by early embryonary death increasing the number of false positives in days 31 to 35 post insemination. We conclude that a negative diagnosis of gestation by ultrasound practice after 30 days post insemination is considered to be accurate method to monitored empty cows which can be reprogram for a synchronization method for rapid insemination.