Interspecies pregnancy of Spanish ibex (Capra pyrenaica) fetus in domesticgoat (Capra hircus) recipients induces abnormally high plasmatic levels ofpregnancy-associated glycoprotein

Interspecies embryo transfer could be a valuable tool in preservation progr ams of endangered species. In this work the results of both interspecific-m onospecific (ibex-in-goat) and interspecific-bispecific (mixed-species; ibe x+goat-in-goat) embryo transfers in the capra genus are reported. The aim o f this work was to compare the PAG plasmatic profiles occurring in these in terspecific gestations to those encountered in normal (i.e. intraspecies) p regnancies of Spanish ibex and domestic goat. Spanish Ibex females were sup erovulated with 9 mg NIADDK-oFSH-17 and embryos were surgically collected 5 .5 d after estrus. Two embryos were transferred per recipient. Domestic goa t recipients were previously mated either to vasectomized domestic bucks (n =17 females; interspecific-monospecific gestations) or to fertile ones (n=9 females; interspecific-bispecific gestations). Intraspecific pregnancies w ere obtained by natural mating between males and females of the same specie s (Spanish ibex: n=6; domestic goat: n=1). Pregnancy rate diagnosed by prog esterone was low in both interspecific-monospecific (7/17) and interspecifi c-bispecific (3/9) transfers. None of the monospecific (0/7) and 2 (2/3) of the bispecific established pregnancies developed to term. Ibex-in-ibex PAG profile showed 2 similar peaks of 60 to 70 ng/mL on Days 34 and 153 of pre gnancy, while goat-in-goat had the maximum Value (60 to 70 ng/mL) at Day 50 , decreasing slightly afterwards until parturition. Mixed-species gestation s (ibex+goat in goat) showed a first peak of 500 to 1000 ng/mL on Day 70 an d a second one (200 to 500 ng/mL) on Day 140 of pregnancy. Four ibex-in-goa t gestations that terminated with the expulsion of dead fetuses at Days 110 to 170 had their maximum PAG values (100 to 700 ng/mL) on Days 60 to 90. W e conclude that it is possible to achieve pregnancies after transfer of ibe x embryos into domestic goats, but this requires a great change of the PAG profiles, which increase significantly. Live ibex kids can be produced when embryos from both species share the uterus. This is the first report of su ccessful interspecific pregnancies in the capra genus. (C) 1999 by Elsevier Science Inc.