Testosterone concentrations in plasma of dairy cows with ovarian cysts

Testosterone in plasma was measured by radioimmunoassay in cows with ovarian cysts and in cows during the estrous cycle. Concentrations of testosterone in plasma (60.8 +/- 2.7 pg/ml; mean +/- standard error) in cows with ovarian cysts were variable but within the range in cows during the estrous cycle. Mean concentrations of testosterone in plasma increased from 46.3 pg/ml at estrus to 85.1 pg/ml on day 13 of the estrous cycle. In cows with ovarian cysts, concentrations of testosterone in plasma declined within 24 h following prostaglandin F2 alpha and tended to increase by 9 days following gonadotropin releasing hormone. The role of testosterone in estrual behavior and inhibiting resumption of ovarian cycles is likely minimal.