229 OOCYTE RECOVERY, IN VITRO FERTILIZATION AND EMBRYO TRANSFER IN THE SERVAL (LEPTAILURUS SERVAL)

Abstract

Servals are medium size (9 to 18 kg) spotted cats found in sub-Saharan Africa that are protected by CITES under Appendix II regulations. There are at least six sub-species, one of which is listed as Endangered by the U.S. Endangered Species Act. In vitro-derived embryos have been produced in at least one-half of the 36 species of nondomestic cats, and kittens have been born after embryo transfer in six species. In the present study we evaluated (1) ovarian response of servals to repeated exogenous gonadotropin stimulation, and (2) in vitro and in vivo developmental ability of in vitro-derived embryos. One two-year-old and one five-year-old female were treated six and three times, respectively, over a 3.5-year period, with a total of 20 or 25 IU of porcine FSH (i.m.; Sioux Biochem, Sioux City, IA, USA) administered daily over four days during interestrus. On Day 5, 15 IU of porcine LH (i.m.; Sioux Biochem) was given, and laparoscopic oocyte retrieval was performed 24 h later. A total of 234 preovulatory oocytes were recovered: 182 (mean = 30.3) from the two-year-old and 52 (mean = 17.3) from the five-year-old female. A total of 91 and 91 oocytes were recovered at retrievals 1 through 3 and 4 through 6, respectively, from the two-year-old donor. Eighty oocytes from the two-year-old donor were inseminated with cooled (24 h, 4°C) semen. Frozen semen from the same male was used to inseminate 102 oocytes from the two-year-old female and 52 oocytes from the five-year-old female. Overall, 136 embryos (58% cleavage frequency) were produced: 119 (65% cleavage frequency) from the two-year-old and 17 (33% cleavage frequency) from the five-year-old female. Cleavage frequency of oocytes from the two-year-old female inseminated with cooled or frozen semen was similar, 68% (54/80) and 64% (65/102), respectively. Embryos were cultured for 5 or 6 days before controlled rate cryopreservation or uterine transfer (Gómez et al. 2003 Theriogenology 60, 239–251). On Day 5, 66 early to mid-stage morulae were cryopreserved at a slow controlled rate. Sixty Day 5 and 18 Day 6 embryos were auto-transferred to a recipient (8 to 26/transfer) in a total of six surgical procedures, of which five were with fresh embryos (n = 70) and one was with cryopreserved embryos (n = 8). The sixth embryo transfer procedure (26 fresh embryos) resulted in the unassisted birth of a live male kitten on Day 77 of gestation. We have shown that in vitro-derived embryos can be generated in the serval and that oocyte retrieval rates and cleavage frequencies are comparable to those reported for other species of mid-sized nondomestic cats. The nominal incidence of pregnancy and frequency of embryo survival may be improved by transferring early cleavage staged embryos into the oviduct, as demonstrated in the African wildcat (Felis silvestris lybica; Gómez et al. 2004 Cloning and Stem Cells 6, 247–258).

This work was partially funded by the Dan Heard Conservation Challenge Grant.