Evaluation of pregnancy-associated glycoprotein (PAG) test used in milk for the early pregnancy diagnosis of dairy cows

In this study, it was aimed to evaluate and compare the effectiveness of pregnancy-associated glycoprotein (PAG) levels in the milk samples of dairy cows in their early pregnancy diagnosis. A total of 229 Holstein cows, aged between 3 and 7 years old, inseminated in the first natural estrus after completing the voluntary waiting period and not returning to their estrus at 18-24 days after insemination, were used as animal material. Ultrasound examination was performed on the 29th day after insemination to diagnose early pregnancy, and milk samples were collected on the same day to determine PAG levels. The ultrasound examination was used as a reference test. The sensitivity, specificity, predictive values, and accuracy rates of the milk PAG test were found to be 92%, 100%, 100%, 91.7%, 95.8%, respectively, and the agreement between the ultrasound and milk test results was excellent according to the Kappa value (κ=0.919). The overall validity of the milk test was found to be 95.75%. The false negative rate of the milk PAG test was found as 8%. The false negative results were thought to be caused by embryonic deaths. In conclusion, the milk PAG test is a reliable test for early pregnancy diagnosis in dairy cows.