Factors affecting in vitro oocyte maturation in Southern white rhinoceros(Ceratotherium simum simum)

Authors

DOI:

https://doi.org/10.36303/JSAVA.684

Keywords:

assisted reproduction, oocyte pick-up, oocyte maturation, rhinoceros

Abstract

Background: Population numbers of free-roaming rhinoceros are dwindling while natural breeding in captive populations is challenged by sub-optimal fertility. When natural breeding programmes fail and population numbers continue to decline, the use of assisted reproduction technologies (ART) as a conservation tool to save wildlife species from extinction is imperative. Assisted breeding programmes in rhinoceros are challenging and attempts to develop species-specific ART beyond artificial insemination have been limited. This study evaluates various ex- and in-situ factors that could potentially affect in vitro oocyte maturation (IVM) in the Southern white rhinoceros (SWR).

Objectives: To identify predictors of oocyte maturation following ovum pick-up (OPU) procedures performed on a large number of rhinoceros under different management conditions.

Methods: Data from 85 OPU procedures between November 2018 and June 2023 were obtained for this study. A total of 23 factors (three animal, four environmental, 16 laboratory) were evaluated as potentially affecting IVM success.

Results: Of the 85 procedures performed on 59 SWR, a total of 265 oocytes were collected with a median of two oocytes (range 0–18) per OPU. Eighteen (18) of the procedures yielded 0 oocytes. The overall maturation rate was 30% (80/265), and six identified factors had significant univariate associations with maturation outcome, of which three remained in the multivariable model.

Conclusion: Farming system, season and oocyte density in maturation medium (> 100 ul/oocyte) were independently associated with improved maturation success (p < 0.05).

Author Biographies

  • M Smuts, University of Pretoria

    Department of Production Animal Studies, Faculty of Veterinary Science, University of Pretoria and Centre for Veterinary Wildlife Research, Faculty of Veterinary Science, University of Pretoria, South Africa

  • PR De Bruin, University of Sydney

    Department of Production Animal Studies, Faculty of Veterinary Science, University of Pretoria and Reproduction and Perinatal Centre, Faculty of Medicine and Health, University of Sydney, Australia

  • GT Fosgate, University of Pretoria

    Department of Production Animal Studies, Faculty of Veterinary Science, University of Pretoria and Centre for Veterinary Wildlife Research, Faculty of Veterinary Science, University of Pretoria, South Africa

  • L Vorster, University of Pretoria

    Department of Production Animal Studies, Faculty of Veterinary Science, University of Pretoria, South Africa

  • M De La Rey, University of Pretoria

    Department of Production Animal Studies, Faculty of Veterinary Science, University of Pretoria and Rhino Repro NPC, South Africa

  • C Lichtenberg, University of Pretoria

    Department of Animal and Wildlife Science, Faculty of Natural and Agricultural Sciences, University of Pretoria and Rhino Repro NPC, South Africa

  • C Young, San Diego Zoo Wildlife Alliance

    Beckman Center for Conservation Research, San Diego Zoo Wildlife Alliance, United States of America

  • BS Durrant, San Diego Zoo Wildlife Alliance

    Beckman Center for Conservation Research, San Diego Zoo Wildlife Alliance, United States of America

  • LCR Meyer, University of Pretoria

    Department of Production Animal Studies, Faculty of Veterinary Science, University of Pretoria and Centre for Veterinary Wildlife Research, Faculty of Veterinary Science, University of Pretoria, South Africa

  • DE Holm, University of Pretoria

    Department of Production Animal Studies, Faculty of Veterinary Science, University of Pretoria and Centre for Veterinary Wildlife Research, Faculty of Veterinary Science, University of Pretoria, South Africa

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Published

2025-05-15

Issue

Vol. 96 No. 1 (2025)

Section

Original Research

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Copyright (c) 2025 Author/s

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This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License.