Plasma levels of oestradiol-17 beta in the pre-puberal heifer treated to induce superovulation

The plasma concentrations of oestradiol-17β have been measured by radioimmunoassay in pre-puberal calves following treatments used to induce superovulation (PMSG/HCG and PMSG/FGA/HCG). Before treatment, in almost all animals, the concentrations of oestradiol-17β were different from zero (2 to 8 pg/ml). The highest concentrations were measured around 130 h. after the beginning of treatment, before ovulation (150 to 2050 pg/ml). The curves showing the changes in hormonal levels have the same form as those of follicular growth measured using morphological criteria. The two hormonal treatments resulted in similar oestradiol-17β concentrations.