Abstract   

    The plasma progesterone concentration was measured in 18 normal cyclic Holstein Friesian cows following artificial insemination for diagnosis of early pregnancy. The blood samples were collected from 10 multiparous and 8 heifer cows on every 4th day following insemination until day 41 post insemination. The plasma progesterone concentration was measured with the help of direct enzyme immunoassay. The values of plasma progesterone concentration ranged between 2.3 to 4.0 ng/ml and 0.1 to 2.2 ng!ml in pregnant and non-pregnant groups, respectively. The plasma progesterone concentration of I .0ng/ml and above on test days were taken as pregnant for both multiparous and heifer cows. The accuracy of this test for diagnosing early pregnancy was 7 1.4% on day 2 post insemination and 83.3% on day 25 post insemination. The non pregnancy diagnosis by this test was 100% accurate on all days of test. Subclinical endornetritis and/or early embryonic deaths seen to interfere with exact diagnosis of pregnancy.    

Key words: Holstein Friesian cows, plasma progesterone, pregnancy