Theriogenology41:491-498,1994 OVULATION RATE, ZYGOTE RECOVERY AND FOLLICULAR POPULATIONS IN FSH-SUPEROVULATED GOATS TREATED WITH PGFZ, AND/OR GnRH R.L. Krisher,' F.C. Gwazdauskas," R.L. Page,' C.G. Russell,' R.S. Canseco,' A.E.T. Sparks,' W.H. Velander,' J.L. Johnson 3 and R.E. Pearson ’ Departments of 'Dairy Science, 'Chemical Engineering and 3Anaerobic Microbiology Virginia Polytechnic Institute and State University Blacksburg, VA 24061, USA Received for publication: zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQP December I, 1992 Accepted: October 7, 1993 ABSTRACT Follicular development and ovulation were examined in superovulated Nubian and Nubian-cross dairy goats following prostaglandin F (GnRH) treatmene (PGF ) and/or gonadotropin releasing hormone Es&us was synchronized with Synchromate-Be implants. Superovulation was induced with follicle stimulating hormone (FSH) and augmented with GnRH and/or PGF2,. treatment was administered on Day 2 of superovulation. The PGFZ, Implants were removed from all goats on Day 3 of superovulation. The GnRH treatment was administered 24 h after implant removal. All does were exposed to fertile males for 48 h at the time of GnRH injection. Surgical embryo recovery and ovarian response evaluation were conducted 64 to 78.5 h after implant removal. The number of ovulations was higher with GnRH treatment (18.5 + 7; x + SEM) than that in the controls (5.3 + 4.1; P < 0.05). There were fewer follicles in the GnRH-treated does than in the untreated does (10.9 + 2.9 vs 22.1 f 3.2; P < 0.05). The number of follicles smaller than 4 mm in diameter (5.8 + 0.8) did not differ between treatments. The GnRH-treated does had fewer 4- to 8-mm follicles (4.2 & 2.0 vs 9.1 * 1.6; P < 0.05) and fewer follicles larger than 8 mm (0.7 + 1.4 vs 7.3 + 1.6; P < 0.01) than the controls. Predicted times for l- and 2-cell embryo recoveries were 68.5 and 73.7 h following implant removal, respectively. This study demonstrates that GnRH is an effective supplement used with FSH superovulation regimens in dairy goats. Moreover, GnRH provides for enhanced early embryo collection for DNA microinjection studies. Key words: goat, superovulation, GnRH, PGF,, INTRODUCTION The production of transgenic goats requires the collection of large numbers of pronuclear stage embryos for DNA microinjection. a Correspondence and reprint requests. zyxwvutsrqponmlkjihgfedcbaZYXWVUT Copyright Q 1994 Butterworth-Heinemann