Milk Progesterone Concentration and Production in Superovulated Holstein Cows

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Abstract
Six Holstein cows in a commericial herd (3 superovulated and 3 controls) and 8 Holstein cows superovulated a total of 12 times in an experimental herd were studied. Superovulation was induced primarily by treatment with FSH and PGF2.alpha.. Milk was weighed twice daily for 30 days following treatment in the commerical herd with no effect on production. Milk samples were saved on Monday, Wednesday and Friday to determine progesterone content. Last milk at mid-cycle averaged 8.2 ng/ml of progesterone for the cows in the experimental herd and 7 days after superovulation they averaged 52.6 .+-. 10.2 ng/ml (mean .+-. SE) of progesterone. The correlation with number of embryos recovered was 0.86. Milk progesterone may be useful in monitoring superovulatory response. Injection of PGF2.alpha. into superovulated cows 9 days after a previous injection did not initiate a new estrous cycle, a fact accurately monitored by milk progesterone determinations.