Characterizing the reproductive biology of the female pygmy hippopotamus (Choeropsis liberiensis) through non-invasive endocrine monitoring

Gabriella L Flacke; Franz Schwarzenberger; Linda M Penfold; Susan L Walker; Graeme B Martin; Robert Peter Millar; Monique C J Paris

doi:10.1016/j.theriogenology.2017.07.017

Characterizing the reproductive biology of the female pygmy hippopotamus (Choeropsis liberiensis) through non-invasive endocrine monitoring

Theriogenology. 2017 Oct 15:102:126-138. doi: 10.1016/j.theriogenology.2017.07.017. Epub 2017 Jul 19.

Authors

Gabriella L Flacke¹, Franz Schwarzenberger², Linda M Penfold³, Susan L Walker⁴, Graeme B Martin⁵, Robert Peter Millar⁶, Monique C J Paris⁷

Affiliations

¹ School of Animal Biology, University of Western Australia, 35 Stirling Highway, Crawley 6009, Australia; Institute for Breeding Rare and Endangered African Mammals (IBREAM), Edinburgh EH3 6AT, United Kingdom. Electronic address: Gabriella.Flacke@miamidade.gov.
² Department of Biomedical Sciences, Unit of Physiology, Pathophysiology and Experimental Endocrinology, University of Veterinary Medicine (Vetmeduni Vienna), Veterinärplatz 1, 1210 Vienna, Austria.
³ South East Zoo Alliance for Reproduction & Conservation (SEZARC), 581705 White Oak Road, Yulee, FL 32097, USA.
⁴ Chester Zoo, Upton-by-Chester CH2 1LH, United Kingdom.
⁵ School of Animal Biology, University of Western Australia, 35 Stirling Highway, Crawley 6009, Australia.
⁶ Institute for Breeding Rare and Endangered African Mammals (IBREAM), Edinburgh EH3 6AT, United Kingdom; Mammal Research Institute and Centre for Neuroendocrinology, University of Pretoria, Department of Zoology and Entomology, Pretoria 0084, South Africa; Institute for Infectious Diseases and Molecular Medicine, University of Cape Town, Cape Town 7925, South Africa.
⁷ School of Animal Biology, University of Western Australia, 35 Stirling Highway, Crawley 6009, Australia; Institute for Breeding Rare and Endangered African Mammals (IBREAM), Edinburgh EH3 6AT, United Kingdom; Mammal Research Institute and Centre for Neuroendocrinology, University of Pretoria, Department of Zoology and Entomology, Pretoria 0084, South Africa; College of Public Health, Veterinary and Medical Sciences, James Cook University, Townsville 4811, Australia.

PMID: 28759835
DOI: 10.1016/j.theriogenology.2017.07.017

Abstract

The pygmy hippopotamus (Choeropsis liberiensis) is endangered in the wild and very little is known about its reproductive biology. In zoological facilities, this species experiences a number of reproductive issues that complicate breeding management, including a high rate of stillbirths and failure of many pairs to reproduce. We conducted a comprehensive study to evaluate reproductive cycles and pregnancy in this species using enzyme immunoassays (EIAs) for fecal hormone metabolite analysis. Fresh fecal samples were collected twice weekly for a one to three year period from 36 female pygmy hippos housed at 24 zoological institutions. Samples were analyzed in three separate laboratories. Three progestogen metabolite EIAs (Pg-diol: 5β-pregnane-3α,20α-diol 3HS:BSA; PdG: pregnanediol-3-glucuronide R13904; mono-P4: Quidel clone 425) and three estrogen metabolite EIAs (E2a: estradiol-17β-OH 17-HS:BSA; E2b: estradiol 17β R0008; E2c: estradiol 17β R4972) accurately reflected reproductive events. Average estrous cycle length was 31.8 ± 7.4 days based on estrogen metabolite peaks and 30.9 ± 7.3 days based on nadir to nadir progestogen metabolite concentrations. Cyclical patterns in both estrogen and progestogen metabolites were detected throughout the year, indicating a lack of seasonality. Estrogen metabolite peaks were also observed during pregnancy and lactation, suggesting that follicular development occurs during both reproductive states. Pregnancy was most reliably demonstrated by elevation in progestogen metabolites (Pg-diol or PdG) in the second half of gestation. Average gestation length based on breeding to calving date was 203 ± 4 days for 15 pregnancies. This comprehensive overview of the reproductive biology of the female pygmy hippo provides valuable data for guiding long-term breeding management for this endangered species and serves as a baseline for future studies addressing the potential influence of social structure, diet, body condition, and other husbandry factors on estrous cycling and reproduction.

Keywords: Enzyme-linked immunoassay (EIA); Estrogen; Estrous cycle; Gestation; Progestogens; Pygmy hippo.

MeSH terms

Animals
Animals, Zoo
Artiodactyla / physiology*
Feces / chemistry*
Female
Immunoenzyme Techniques
Pregnancy
Pregnancy, Animal* / physiology
Reproduction / physiology*