The aim of this study was to investigate a possible relationship between the serum activity of early pregnancy factor (EPF) on the days 7 and 21 and the blood serum levels of progesterone on the day 21 following insemination and on the day 45 rectal examination findings in cows. Possible use of EPF parameter in early diagnosis of pregnancy was also sought.

Sixty Brown Swiss cows were used in this study. Blood samples were collected on the days 7 and 21 for EPF activity and on the day 21 for progesterone analysis. Serum EPF and progesterone levels were determined by Rosette Inhibition Test (RIT) and radioimmunassay, respectively. In the RIT analysis, findings above 4 were accepted as pregnant and those equal or below 4 as non-pregnant. The cows with serum progesterone levels above 2.30 ng/ml were evaluated as pregnant.

RIT and serum progesterone levels were compared with the rectal examination findings on the day 45 following insemination.

Based on the rectal examination findings, the accuracy EPF of on the days 7 and 21 and progesterone results on the day 21 were 54.7%, 70.7% and 67.4%, respectively, in the pregnant cows. All three parameters proved to be 100% accurate in the non-pregnant animals. Early embryonic deaths affected the diagnosis of early pregnancy results significantly based on the serum EPF and progesterone parameters. Although fertilisation rate of the cows was 88.3%, embryonic deaths occurred in 45.3%.

In conclusion, these findings suggested that the determination of EPF activity may be used for diagnosis of early pregnancy and for monitoring continuation of pregnancy. RIT and progesterone analysis methods may be more reliably used for determination of the non-pregnant cows than the pregnant ones.