Optimized heterologous in vitro fertilization with Iberian ibex sperm and domestic goat oocytes

Assisted reproductive technologies are key to maintain genetic stocks of endangered wild species, such as the Iberian ibex (Capra pyrenaica). Due to the low availability of ibex ovaries, heterologous in vitro fertilization (IVF) with domestic goat (Capra hircus) oocytes constitutes an excellent alternative to determine the fertilization capacity of ibex sperm doses. The aim of this study was to optimize heterologous ibex-goat IVF procedures by testing two different IVF media (TALP and SOF) and to determine whether estrous sheep serum (ESS) is required for fertilization. We found that TALP medium provides optimal conditions to conduct heterologous ibex-goat IVF, yielding blastocyst rates above 50%, and that supplementation with ESS is not required. No differences were found in embryo quality between embryos fertilized in TALP, SOF alone, or SOF supplemented with 2 or 20% ESS, based on the analysis of cell lineages development at day (D) 8 and D10 of development. Optimized heterologous ibex-goat IVF, together with embryo quality assessment through lineages development analysis, constitute an excellent system to assess fertilization capacity of ibex sperm doses, and opens the possibility of performing homologous in vitro embryo production in this species.