Semen collection and ejaculate characteristics of the Leopard Tortoise (Stigmochelys pardalis).

Dawn M Zimmerman,Mark A Mitchell

doi:10.1093/conphys/cox062

Abstract

The preservation of spermatozoa is an important tool used in conservation programs to increase the genetic diversity of threatened and endangered species. Although routinely used to manage conservation programs for higher vertebrates, there have been limited attempts to establish reproductive assistance programs for tortoises. The purpose of this study was to develop a model for collecting and characterizing semen in Testudinidae. Semen was collected from 13/16 (81.2%, 95% CI: 62-100) adult male leopard tortoises (Stigmochelys pardalis) via electroejaculation under propofol anesthesia. Semen samples were collected most frequently after the second series of electrostimulations (6/13, 46.1%), with fewer animals producing semen after the first (5/13, 38.5%) or third (2/13, 15.4%) electrostimulations. The average volume of a semen sample in the tortoises was 0.26 ml (standard deviation: 0.16, minimum-maximum: 0.1-0.6), the average spermatozoal concentration was 101.62 × 106/ml, and the average motility at time of collection was 57.3%. A rapid decrease in motility was observed in refrigerated samples over 24 h resulting in a median motility of 0% at 24 h post-collection. The results of this study suggest that electroejaculation is a safe and efficient method for collecting semen from leopard tortoises.

Highlights

To date, ~335 species of chelonians from the phylogenetic order Testudines have been identified
The results of this study suggest that electroejaculation is a safe and efficient method for collecting semen from leopard tortoises
The present study suggests that electroejaculation is an effective means by which to safely collect semen from leopard tortoises; it is notable that semen could not be collected from three (19%) of the tortoises

Summary

Introduction

To date, ~335 species of chelonians from the phylogenetic order Testudines have been identified (van Dijk et al, 2014). Of these species, 107 (31.9%) are Critically Endangered [CR] or Endangered [EN]; this number increases to 167 (49.9%) for threatened species inclusive of CR, EN and vulnerable [VU] populations, and to 175 (52.2%) species when comprising threatened and recently extinct populations (IUCN, 2010; van Dijk et al, 2014). By estimating threat rates for data-deficient species and including recently extinct species, more than half of all modern chelonian species are either threatened or extinct—a number that has increased substantially over the years and makes chelonians one of the most endangered groups of vertebrates. Based on the risks facing this group and the ongoing pressures they face, the significance and need of conserving chelonian species is apparent

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