In vitro fertilization of cattle and sheep follicular oocytes by goat spermatozoa

Abstract The study compared efficiency of goat spermatozoa to penetrate cattle and sheep intact follicular oocytes, and evaluated effect of cumulus cells on the ability of sperm to penetrate heterologous oocytes. Ruminant cumulus-oocyte complexes (COC) were obtained by aspiration of ovarian follicles and were matured by culturing them in medium 199 plus goat serum in microdrops under paraffin oil for 24 h. Fresh semen was collected by artificial vagina, incubated for 4 h at room temperature, washed, and spermatozoa were then suspended in Talp medium plus goat serum and treated for capacitation by using incubation at 39°C and heparin. In the first experiment, goat, cattle and sheep matured oocytes were incubated in goat sperm preparation, whereas in the second experiment, cattle and sheep oocytes either partially (cumulus enclosed oocytes = + ) or totally denuded from granulosa cells (denuded oocytes = − ) were added to the prepared spermatozoa. Fertilization rates obtained in the first experiment (goat sperm-goat oocytes: 91.3%; goat-cattle: 82.7%; and goat-sheep: 79.8%, P > 0.05), showed that goat sperm were highly efficient in penetrating cattle and sheep oocytes as compared with homologous fertilization, and that goat sperm penetrated equally well cattle and sheep oocytes: Fertilization rates from the second experiment (cattle oocytes: +74.0%, −88.89%; sheep oocytes: +68.42%, −78.85%, P > 0.05), showed that cumulus cells did not modify the ability of goat spermatozoa to penetrate heterologous oocytes.