Establishment of a Latex Immunochromatography for Bovine Early Pregnancy-related glycoproteins and its Application in the Diagnosis of Bovine Pregnancy

Background Early pregnancy diagnosis in dairy cows is an important part of the production processes. Accurate early pregnancy diagnosis can help veterinarians identify open cow as soon as possible and carry out the second breeding earlier, which is of great significance for improving reproductive efficiency of dairy cow. Bovine early pregnancy-related glycoproteins (PAGs) are produced by placental trophoblast cells and is considered as a reliable indicator for the diagnosis of early pregnancy in cows. In this study, a rapid immunochromatography based on latex microspheres for detecting PAG proteins was established with two monoclonal antibodies specific to PAG protein. Results The samples collected from 28 days after breeding of 559 Holstein cows were used to diagnose pregnancy, and the results were verified by ultrasound examination and commercial ELISA kit tests. The results showed that the minimum detection limit of the established latex immunochromatography for PAG protein was 0.2ng/ml, and the analytical specificity is very high. Furthermore, compared to B-ultrasound, the sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of this method for pregnancy diagnosis was 99.25%, 90%, 91.03%, 99.15%, and 94.68%, respectively, and the kappa value is 0.89, which demonstrated that the pregnancy diagnosis results of the test strip method have high consistency with ultrasound. Compared with commercial ELISA kits, the positive coincidence rate, negative coincidence rate, and overall coincidence rate of this method was 98.29%, 97.6%, and 98.03%, respectively. This indicated that the test strip has high consistency with the currently widely used ELISA immunological diagnostic method. Conclusion The latex immunochromatographic method established in this study can accurately diagnose pregnant cows and can be used for early pregnancy diagnosis of dairy cows. The method is simple to operate, fast to detect, and the results are easy to interpret, which is of great significance and clinical application value for cow early pregnancy detection.