The comparison of two embryo donor breeds for the generation of transgenic goats by DNA pronuclear microinjection

Abstract

The aim of the present study was to compare two breeds as embryo donors to produce transgenic goats for the production of human granulocyte colony-stimulating factor. Ten Canindé and 11 Saanen goats were used as donors and received a hormonal treatment for oestrus synchronisation. The superovulation was induced with a total administration of 4.4 mg/kg bodyweight NIH-FSH-P1, given in decreasing doses over 3 days. Donors also received 100 μg of GnRH and they were hand-mated at 36 and 48 h after progestagen removal. Embryo recovery was performed by oviduct flushing at 72 h after progestagen removal and the pronuclear embryos were microinjected. Fifty-two recipients of undefined breed were prepared by receiving the same oestrus synchronisation treatment; however, only 32 were used due to the availability of embryos. Embryos were surgically transferred into the oviduct. A significant (P < 0.05) difference was observed in the total number of ovulations when Canindé (12.6 ± 6.9) and Saanen (22.5 ± 10.0) donors were compared. Concerning the microinjectable embryos, Canindé goats produced a greater number when compared with Saanen females (P < 0.05). Twenty recipients received 61 Canindé embryos and, of those, 12 kidded, whereas just 12 recipients received 30 Saanen embryos but just three kidded. In total, three transgenic goats were obtained, of which two were healthy Canindé and one stillborn Saanen. It was possible to develop an efficient protocol to obtain transgenic goats for Canindé but not for Saanen breed, for which some variables such as superovulatory regime and time of breeding should be further studied.