In vitro fertilization of goat oocytes during the non-breeding season

A total of 12 does, from mixed Swiss breeds (11 Alpine and 1 Saanen), compr ising donors (n = 6) and recipients (n = 6), were used in two experiments d uring the non-breeding season (January to June 1997) at the Agricultural Re search Station of Fort Valley State University, Georgia, USA. Immature cumu lus-oocyte complexes (COC) were collected either by laparotomy (surgery, Ex periment 2) or aspirated from ovaries obtained from ovariectomized does (Ex periment I). The oocytes were recovered from 2 to 6 mm diameter follicles a nd matured in vitro for 24 h in TCM-199 medium supplemented with 10% fetal bovine serum (FBS), 100 mu g LH/ml, 0.5 mu g FSH/ml and 1 mu g estradiol 17 beta/ml at 38.5 degrees C in humid 5% CO2 in air. Expanded COC, obtained f rom 24 h maturation, were fertilized as described by Parrish et al. (Parris h, J.J., Susko-Parrish, J.L., Leibfried-Rutledge, M.L., Critser, E.S., Eyes tone, W.H., First, N.L., 1986. Theriogenology 25, 591-600). Methods of oocy te retrieval (laparotomy:vs. ovariectomy) did not affect maturation and fer tilization rates. Although the cleavage rate was significantly higher for o ocytes obtained by ovariectomy (100%) compared to those retrieved after lap arotomy (79%; P < 0.05), there was no significant difference in the percent age of eight-cell (80% vs. 65%; P > 0.05) and morula/blastocyst-stage embry os (90% vs, 65%; P = 0.05) after ovariectomy and laparotomy, respectively. A total of 21 morula/blastocyst-stage embryos were transferred to six recip ients. No pregnancy was detected either by progesterone assay or ultrasonog raphy. Results from this study indicate that oocytes from Swiss Alpine and Saanen breeds born and raised under the climate conditions prevailing in Ge orgia, USA (32 degrees 5'N latitude and 83 degrees 8'W longitude) can be su ccessfully matured and fertilized in vitro, during the nonbreeding season, and that embryo production through in vitro fertilization technology may be an alternative approach to circumvent seasonal;anestrus in temperate clima tes. (C) 2000 Elsevier Science B.V. All rights reserved.