Progesterone concentration in peripheral plasma of laying hens as determined by competitive protein-binding assay

Abstract

The concentration of progesterone in the peripheral blood plasma of laying hens attained a peak value 4–6 h before ovulation. A peak value was not observed on days where ovulation did not occur, i.e., on days when the terminal egg of a sequence was laid.For nine ovulatory cycles the average level was 2.45 ng/ml with a range of 0.5 to 8.8 ng/ml. For five periods covering a day of no ovulation the average was 2.95 ng/ml with a range of 0.5 to 12.5 ng/ml.