norgestomet and Fetal-Death

Survival after transfer of demi-embryos (i.e., half-embryos produced by embryo splitting) to recipients usually is lower than survival after transfer of intact embryos. Reduced survival after demi-embryo transfer could be due to loss of viability after splitting, failure of a viable demi-embryo to prevent corpus luteum (CL) regression in the recipient female, or a combination of factors. From a retrospective analysis of pregnancy and embryo survival rates after demi-embryo transfer in sheep and goats, we report the rescue of caprine demi-embryo pregnancies in which CL regression occurred at the end of diestrus despite the presence of a viable conceptus in the uterus with progestin implants. Day 5 or 6 morulae and blastocysts were flushed from superovulated ewes and does and split into demi-embryos of approximately equal halves. Demi-embryos were either transferred fresh to synchronized recipients of the homologous species or frozen in liquid nitrogen. Approximately half of the recipient does and ewes were treated with norgestomet implants on Day 10 of the embryo transfer cycle and again 2 wk later. Serum collected on Day 25 from recipients with implants was assayed for progesterone to determine if a CL of pregnancy had been maintained. Pregnancy was diagnosed by ultrasonography on Day 35 of gestation. Corpus luteum regression occurred despite the presence of a viable conceptus in the uterus in 6 of 55 progestin-treated caprine demi-embryo recipients and in 0 of 66 ovine demi-embryo recipients. Five of the caprine pregnancies were maintained to term with norgestomet implants and produced 5 live kids. The sixth fetus, which was carried by a progestin implant-treated 8-mo-old doeling, died at approximately 50 d of gestation. These results suggest that, at least in goats, some demi-embryos may provide inadequate signaling for maternal recognition of pregnancy, and such pregnancies can be rescued with progestin treatment to the doe.

Topics: Animals; Drug Implants; Embryo Transfer; Embryo, Mammalian; Female; Fetal Death; Gestational Age; Goats; Luteolysis; Pregnancy; Pregnenediones; Progesterone Congeners; Reproductive Techniques; Retrospective Studies; Superovulation

Threefold thorough gynecological investigations were carried out with a total of 108 heifers with normal cycle, which remained uninseminated--in their choice, treatment with hormonal preparations, and transplantation of embryos, reducing their number up to 76. With the first test group of 35 heifers estrus was synchronized with implants, containing 3 mg norgestomet each. On the 9th day these were removed, and the heifers were injected with 500 IU PMSG (Intervet) each. The animals of the second test group (73 in number) were injected with 7.5 mg prostaglandin F2-alfa at 11-day intervals. The conception rate was 31 per cent higher with heifer-recipients treated with norgestomet implants and serum gonadotropins. Death was established with 47 transplanted embryos (61.8 per cent). With 19 embryos (25 per cent) death set in on the 21st day, and with 28 ones (26.8 per cent)--within the period of the 60th days of pregnancy up to calving. In 17.10 per cent of the transplanted embryos migration was seen toward the opposite horn, on the side of which the ovary contained no yellow body.

Topics: Animals; Cattle; Drug Evaluation; Embryo Transfer; Estradiol; Estrogens, Conjugated (USP); Estrus Synchronization; Female; Fetal Death; Gonadotropins, Equine; Pregnancy; Pregnenediones; Prostaglandins F, Synthetic; Prostaglandins, Synthetic; Time Factors