Pages: 36-43

Abstract

Accuracy and precision in diagnosing estrus, time of insemination and early detection of pregnancy are among the main factors for a successful dairy cattle reproduction system. This study was implemented to evaluate the accuracy of Rapid P4 milk progesterone measurement kit for detecting estrus and pregnancy in dairy cows and comparing them with other conventional methods in the northeast of Iran. The study was performed on 30 Holstein cattle in the second and third calvings in Golestan province (Gonbad) and North Khorasan Province (Bojnourd) to investigate the accuracy and precision of P4 kit for detecting estrus and pregnancy in cows. During the study, the cattle were examined and verified for estrus and artificial insemination was carried out on them. On days 19, 20, 22, and 24 following the artificial insemination, milk samples were taken from the cattle to perform P4 tests, as well as blood samples to measure estrogen and progesterone in blood and milk using Dia metra commercial kit (Italy, Progesterone Elisa, and Estradiol Elisa). Out of 30 inseminated cattle, 7 had a progesterone level of less than 2 ng/ml in plasma and milk, which were marked as low progesterone samples by Rapid P4 test, and all of them showed estrus eventually. Although ultrasound and rectal examination verified pregnancy in days 35 and 45 following the insemination in 23 cattle, 3 were marked as non-pregnant by P4 test and 20 were diagnosed as true pregnant cows. In this case, the accuracy and precision of P4 kit in detecting true pregnancy was 87% and regarding the false pregnancy, it was 13%. Therefore, determining the amount of steroid hormones using ELISA or commercial kits can be used for assessing the reproductive status of dairy cows.