Plasma oestrogen and progesterone in relation to superovulation and egg recovery in the cow

Abstract

Pregnant mares serum gonadotrophin (PMSG) was used in combination with prostaglandin F2alpha or its analogues to induce superovulation in 25 heifers. Total unconjugated oestrogen and progesterone were determined in peripheral plasma of these superovulated animals, and the levels compared with those found during the normal oestrous cycle. A very high level of oestrogen was found between day 3 and 6 after superovulation, and it seems likely that large unovulated follicles were responsible for the excess steroid. Similarly, progesterone levels were raised in the superovulated animal presumably due to production by the numerous corpora lutea. In two heifers, in which overstimulation of follicular development had occurred, there were no ovulations in one of the animals while in the other animal there were 16 ovulations but early regression of corpora lutea was indicated. It is concluded that the poor recovery of eggs on day 6 after superovulation could have been due to deleterious effects of high levels of oestrogen on either the motility of the genital tract causing the premature transport of eggs, or the properties of the zona pellucida.

Gonadotrophin-induced abnormalities in sheep oocytes after superovulation

“…The oocytes from such ovaries are used in many studies on maturation despite reports showing lowered fertilization rates and increased preimplantation losses associated with these procedures (Miller & Armstrong, 1981;Evans & Armstrong, 1983). The cause of the embryonic abnormalities has previously been ascribed to the elevated levels of circulating steroid in PMSG-treated animals (Booth, Newcomb, Strange, Rowson & Sacher, 1975). Our results confirm that PMSG causes excessive follicular steroid secretion but also focusses attention on the adverse effects of this gonadotrophin on the maturing oocyte.…”

Incidence of Premature Luteal Regression in Ewes Superovulated with a Single Injection of Follicle-Stimulating Hormone Combined with Equine Chorionic Gonadotropin.

“…Similar results have been reported in ewes [10] and goats [11]. However, prematurely regressed CL has been observed in suprovulated ewes [12][13][14], cows [15] and goats [16][17][18]. Ryan et al [13] reported that the proportion of ewes that ovulated and subsequently had M chorionic gonadotropin (eCG) has been conventionally used for superovulation in ewes [1][2][3][4].…”

Dose Response to a Single Intramuscular Injection of FSH Dissolved in Polyvinylpyrrolidone for Superovulation in Cows.

“…Similar findings were obtained in previous studies in which cows were superovulated with various doses of PMSG [7][8][9],HMG [10] and FSH-P [11]. These studies suggested that the ovarian response and variability in ova/embryo quality increased with the dose.…”