Abstract
SUMMARY: A significant (P < 0·05) drop in follicle stimulating hormone (FSH) and luteinizing hormone (LH) content of the pituitary was shown to occur in the cow during the period 0–18 hr. after the onset of oestrus. Calculation of the ratio of LH to FSH in the pituitary during the ovulatory period, suggests that this ratio varied and hence that the ratio of LH to FSH secreted may also vary.