THE RESPONSE TO OVARIAN HORMONE ADMINISTRATION IN THE COW ESTIMATED FROM THE PHYSICAL PROPERTIES OF CERVICAL SECRETIONS

Abstract

SUMMARY Hexoestrol and progesterone were given to three ovariectomized cows and the consistency of mucus taken from the cervix uteri was measured. Whenever either of the hormones was clearly predominant, as in normal oestrus and during pregnancy, the pattern of changes in the consistency of the mucus found in the intact animal could be faithfully reproduced. Attempts to simulate the dioestrous phase gave indefinite results. The levels of hormone administration corresponding to the different phases of the reproductive cycle varied from 0·1 to 0·8 mg/day for hexoestrol and 10–20 mg for progesterone, rising to 70 mg during attempts to simulate the last third of pregnancy. All hormones were given by daily subcutaneous injection. The 'oral/subcutaneous ratio' for hexoestrol, as judged by the consistency of cervical mucus, was found to be about 10. During a separate experiment on intact heifers, it was observed that mucus much more like the normal type was produced by injections of oily solutions of hormones than by tablet implants or by injections of microcrystals.