108CRYOPRESERVATION OF GERMPLASM FROM HERITAGE BREEDS OF DOMESTIC LIVESTOCK: SEASONAL EFFECTS ON SUPEROVULATION RESPONSE AND EMBRYO PRODUCTION

Abstract

There is an urgent need to preserve the genetic diversity of rare breeds of domestic livestock. However, it is unknown if conventional superovulation methods are effective in unimproved breeds. The establishment of germplasm cryostorage banks requires the ability to produce viable preimplantation stage embryos. To our knowledge, we describe here the first successful production and cryopreservation of embryos from Gulf Coast Native (GCN) sheep and Tennessee Myotonic (TM) goats. Mature GCN ewes and TM does were synchronized (prostaglandin F2α, 7.5–10mg i.m.) and all TM does, and some GCN ewes, were treated with progesterone (20mg sq, 5×on alternate days, prior to FSH treatment, then 10mg i.m. on second day of FSH treatment). Animals were superovulated (FSH, 50–40–30mg bid i.m., decreasing over 3 days) both in April (cycling) and June (anestrous). Females were bred by natural service with a proven male over 24hr, and embryos were collected surgically from the uterus on Day 7. FSH-stimulated cycling TM does produced a total of 15.3±3.0CL and 10.7±7.2 morulae/animal, whereas FSH-treated anestrous TM does yielded 9.0±2.8CL and 7.0±8.4 embryos per animal. Recovered goat embryos were morphologically of good-excellent quality, and were cryopreserved using a conventional multi-step freezing protocol. Cycling GCN ewes responded to FSH simulation and produced 9.7±2.5CL per animal, whereas the ovaries of non-cycling ewes did not respond to exogenous FSH treatment (0CL). This report documents that TM does will effectively respond to FSH superovulation treatment and produce viable embryos during the breeding season and during the anestrous period. In contrast, GCN ewes appear to respond only to exogenous FSH during the breeding season. Collectively, these results demonstrate that the TM and GCN landrace breeds of goats and sheep display differential responses to hormone manipulation; yet, with breed-optimized protocols, preimplantation stage embryos can be obtained for long-term cryostorage of germplasm of heritage breeds of livestock. Supported by and in partnership with SVF Foundation.