Cryopreservation of captive roe deer (Capreolus capreolus) semen M.T. Prieto-Pablos a, * , M.J. Sánchez-Calabuig b , T.B. Hildebrandt a , F. Göritz a , S. Ortmann b , S. Eder c , J. Santiago-Moreno d , R. Hermes a , J. Saragusty a a Department of Reproduction Management, Leibniz Institute for Zoo and Wildlife Research, Berlin, Germany b Department of Evolutionary Biology, Leibniz Institute for Zoo and Wildlife Research, Berlin, Germany c Department of Reproduction Biology, Leibniz Institute for Zoo and Wildlife Research, Berlin, Germany d Departamento de Reproducción Animal, Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria, Madrid, Spain article info Article history: Received 29 October 2015 Received in revised form 22 February 2016 Accepted 26 February 2016 Keywords: Cervid Genomic-bank Electroejaculation Spermatozoon Extender abstract To address the need to preserve current genetic diversity before it is lost forever; further studies to adapt assisted reproductive technologies to various endangered species are needed, among other things. Roe deer (Capreolus capreolus), an over abundant wild deer, can serve as model species to develop or improve sperm cryopreservation of threatened or endangered deer species. The aim of this study was to compare the ability of three diluents (Berliner Cryomedium [BC]; Tris, citric acid, glucose [TCG]; TES, Tris, glucose) to support chilling, cryopreservation (with 5% glycerol; G) and postthaw incubation (at 22  C and 37  C) of roe deer spermatozoa collected by electroejaculation. Berliner Cryomedium was the diluent that better preserved roe deer spermatozoa during refrigeration, able to maintain motility for at least 14 days, longer than the other extenders. BC þ G was the extender of choice for cryo- preservation, showing higher viability compared with TCG þ G (66.7  3.4 vs. 54.5  6.5; P < 0.05) and higher level of acrosome integrity compared with TES, Tris, glucose þ G (79.4  3.4 vs. 67.9  5.0; P < 0.05). Maintaining the samples at 22  C after thawing presented higher values in various parameters compared with 37  C. The knowledge gained through this study can potentially act as a preliminary step toward development of new protocols to help increase the reproductive success of biologically similar, yet endangered, wild species. Ó 2016 Elsevier Inc. All rights reserved. 1. Introduction Accelerated loss of global biodiversity and an increase in the number of endangered and threatened species are matters of great concern. The increased inbreeding wit- nessed in many animal populations is a cause for further concern. Although efforts should be invested into reversing the processes that led to the current dire state, supportive technologies must be developed to preserve current genetic diversity, at least in vitro [1]. Sperm cryopreserva- tion, one such conservation tool, has been of interest to both captive- and wild-populations managers. The biology and reproductive pattern in mammals is well characterized for only a small fraction of species, the vast majority of which are domestic and laboratory spe- cies and species of commercial or scientific interest. This is considered a big obstacle when attempting to apply assisted reproductive techniques such as sperm cryo- preservation, estrus synchronization, or artificial insemi- nation to rare or endangered species [2–4]. The use of model species, such as domestic animal or more accessible wild species, coupled with an increase in the under- standing of basic processes in cryobiology, may help in developing protocols for preservation of spermatozoa from endangered wild species [1,5–7]. Technology could be transferred from well-studied species to related, but less studied, species, possibly leading to improvement in their sperm preservation. However, even when it is * Corresponding author. Tel.: þ49-30-5168-443; fax: þ49-30-5126- 104. E-mail address: prieto@izw-berlin.de (M.T. Prieto-Pablos). Contents lists available at ScienceDirect Theriogenology journal homepage: www.theriojournal.com 0093-691X/$ – see front matter Ó 2016 Elsevier Inc. All rights reserved. http://dx.doi.org/10.1016/j.theriogenology.2016.02.023 Theriogenology xxx (2016) 1–9