Progestogenic activity of the corpus luteum during pregnancy in cows

摘要

Progesterone assays were carried out on milk obtained from 79 Russian Black Pied cows on the day of oestrus and days 10-12 and 19-23 after insemination. Data are tabulated on progesterone concentrations, and the percentages of cows conceiving and failing to conceive in relation to specific ranges in progesterone concentration. In cows that conceived, progesterone concentration on the day of oestrus averaged 0.25 ng/ml less in cows that failed to conceive.