Milk progesterone concentrations were measured in 111 dairy cows for confirming the estrus observation and for the early pregnancy diagnosis.
Of the 56 cows inseminated, 52 cows(92.8%) were an ovulatory estrus, 2 cows(3.6%) were an unovulatory estrus, and 2 cows(3.6%) were the error of estrus observation, respectively.
Milk progesterone concentrations at 21 and 24 days afrer artificial insemination were significantly higher in 23 pregnant cows compared with those in 5 non-pregnant cows(P<0.05).
The accuracy rate for early pregnancy diagnosis in 27 cows achieved when the discriminatory concentration at 21 days after artificial insemination was placed at 2.0 ng/㎖ skim milk, was 91.3% for positive diagnosis and 100% for negative diagnosis, respectively.
These results indicated that milk progesterone determination at 0, 6 and 21 days after artificial insemination can be utilized for confirming the estrus observation and for early pregnancy diagnosis. In conclusion, milk progesterone determination is useful diagnostic tool for monitoring the reproductive performance.
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