Effect of Progesterone and Oestrogen on the Survival and Development of Fertilized Ova in the Ovariectomized Ewe

Abstract

Two experiments were carried out to investigate the importance of progesterone and oestrogen for the survival and development of fertilized ova in ovariectomized ewes. In experiment 1 ewes were treated with progesterone (P) alone or progesterone and 17 p-oestradiol (P + E2) following ovariectomy on the second (day 2) or sixth day (day 6) after mating to vasectomized rams. Fertilized ova were transferred to the ewes either immediately after ovariectomy or on day 6 after ovariectomy on day 2. In experi-ment 2 ewes that had been given an equine anterior pituitary extract to induce multiple ovulation were ovariectomized on day 2 after mating to fertile rams, and then treated with P or P+E2. On day 18 the uteri of all ewes were flushed to recover embryos. Treatment with P commenced immediately after ovariectomy and E2 was given from day 21-to day 5, to ewes ovariectomized on day 2. Ovarian vein blood was collected just prior to ovariectomy and was assayed for its progesterone and oestrogen contents.