155 NOVEL RECIPIENT SYNCHRONIZATION REGIMENS FOR SUCCESSFUL EMBRYO TRANSFER IN THE BRAZILIAN OCELOT FOLLOWING LONG-TERM FROZEN EMBRYO STORAGE

Abstract

The Brazilian ocelot (Leopardus pardalis mitis) is threatened with extinction in southern Brazil due to habitat loss and poaching. As one component of a bi-national conservation program, efforts have been initiated to establish a Brazilian ocelot population in North American zoos through a combination of natural breeding and assisted reproduction. With improved efficiency, embryo freezing and transfer might be useful as a management tool to help achieve this conservation goal. The objectives of this study were to (1) compare two novel ovarian stimulation regimens for embryo recipient synchronization in ocelots and (2) assess embryo transfer success following long-term (7 yrs) storage of frozen ocelot embryos. Adult female ocelots (n = 8), housed individually at a breeding facility in southern Brazil, were used as recipients. Ovarian activity was monitored noninvasively by assessing fecal estrone metabolite concentrations via a validated enzyme immunoassay. Initial fecal monitoring indicated that all females displayed active ovarian cyclicity. For embryo transfer, fecal samples were collected from each cat and assayed daily over a three week period. Females (n = 4) showing two or more consecutive days of increasing estrone were classified as estrual and treated (Trt 1) with two injections of porcine luteinizing hormone (pLH, 3000 IU dose^–1, IM, 13 h interval). Females (n = 4) exhibiting consecutive days of basal estrone levels were considered interestrual and received a combination regimen (Trt 2) of equine chorionic gonadotropin (eCG, 400 IU, IM) followed 85 h later by pLH (3000 IU, IM). Females were anesthetized 50 h after the second hormone injection and evaluated laparoscopically to assess ovarian response. All females exhibited at least one fresh corpus luteum (CL) indicating proper timing of ovulation induction. The number (mean ± SEM) of ovarian follicles (0 v. 3.0 ± 1.5) and CLs (1.0 ± 0.0 v. 3.8 ± 1.8) did not differ (P > 0.05) between treatments. Upon confirmation of ovulation, 3 or 4 frozen embryos (24 embryos total), produced by IVF and frozen in ethylene glycol for liquid nitrogen storage 7 years earlier, were immediately thawed and transferred laparoscopically into one oviduct of each female. At 83 to 84 days post-transfer, two females (one per Trt) each gave birth to one healthy kitten, whereas a third female (Trt 2) experienced dystocia, requiring a C-section to deliver a single healthy offspring. Overall, 38% (3/8) of recipients became pregnant with 33% (3/9) of transferred embryos in pregnant females developing to term. Results indicate that these novel recipient synchronization regimens produce consistent ovulation and a suitable maternal environment for ocelot embryo transfer and that frozen ocelot embryos retain developmental competence after years of storage. Our findings suggest that frozen embryo transfer in ocelots has adequate efficiency for applied usage, allowing international shipment of frozen embryos to be used as a viable alternative to the transport of living ocelots for genetic management (NCRR 015338).