Sensitivity and specificity of pregnancy examinations by means of ultrasound between day 20 and 34 after insemination in dairy cattle

Reducing days open is an important goal in dairy reproductive medicine. The objective of this study was to determine the accuracy of early pregnancy d iagnosis with ultrasound in dairy cows and heifers. Animals that are not pr egnant are to be rebred as soon as possible. Cows and heifers were examined for pregnancy by ultrasound between days 20 and 34 post insemination (pi). The results were compared to those obtained by rectal palpation after 35 t o 48 days pi. Accuracy was determined by crosstabulation. Accuracy was 98 p er cent from day 25 and 29 in heifers and cows, respectively.