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Urinary specific gravity as an alternative for the normalisation of endocrine metabolite concentrations in giant panda (Ailuropoda melanoleuca) reproductive monitoring

Wauters, Jella; Wilson, Kirsten S.; Bouts, Tim; Valentine, Iain; Vanderschueren, Koen; Ververs, Cyrillus; Howie, A. Forbes; Rae, Mick T.; Van Soom, Ann; Li, Rengui; Li, Desheng; Zhang, Hemin; Vanhaecke, Lynn


Jella Wauters

Kirsten S. Wilson

Tim Bouts

Iain Valentine

Koen Vanderschueren

Cyrillus Ververs

A. Forbes Howie

Ann Van Soom

Rengui Li

Desheng Li

Hemin Zhang

Lynn Vanhaecke


Reproductive monitoring for captive breeding in giant pandas is based on behavioural observation and non-invasive hormone analysis. In urine, interpretation of results requires normalisation due to an animal’s changing hydration. Correction of urinary concentrations based on creatinine is the gold standard. In this study, a largely unexplored, easy-to-perform normalisation technique, based on urinary specific gravity (USpG), was examined and compared to creatinine. To this extent, six cycles from two female pandas (SB741(1) and SB569(5)) were monitored through urine analysis for oestrogen, progesterone, ceruloplasmin and 13,14-dihydro-15-keto-PGF2a (PGFM). The Pearson’s correlation between creatinine and USpG was high (r = 0.805–0.894; p < 0.01), indicative for a similar performance of both normalisation methods. However, generally lower values were observed during pro-oestrus and primary (progesterone) rise. This could be associated with huge shifts in appetite, monitored by faecal output (kg) with an averaged > 50% decrease during oestrus and >50% increase during primary progesterone rise. In parallel, respectively highest and lowest creatinine and USpG levels, were measured, with creatinine obviously more affected as a result of linkage with muscle tissue metabolism affected by reproductive hormones. As a consequence, metabolite levels were significantly different between both corrected datasets with significantly higher oestrogen peak levels during oestrus ranging from 2.13–86.93 and 31.61–306.45 ng/mL (USpG correction) versus 2.33–31.20 and 36.36–249.05 ng/mL Cr (creatinine correction) for SB569 and SB741 respectively, and significant lower progesterone levels during primary progesterone rise ranging from 0.35–3.21 and 0.85–6.80 ng/mL (USpG correction) versus 0.52–10.31 and 2.10–272.74 ng/mL Cr (creatinine correction) for SB569 and SB741 respectively. Consequently, USpG correction rendered unbiased profiles, less subject to variation and metabolic artefacts and therefore allowed a more straightforward identification of peak oestrogen and onset of secondary progesterone rise, being potentially advantageous for future studies unravelling key giant panda reproductive events, including (delayed) implantation. The alternative application of USpG as a normalisation factor was further supported by its easy application and environmental and technical robustness.

Journal Article Type Article
Acceptance Date Jul 13, 2018
Online Publication Date Jul 26, 2018
Publication Date Jul 26, 2018
Deposit Date Sep 19, 2018
Publicly Available Date Sep 19, 2018
Journal PLOS ONE
Print ISSN 1932-6203
Publisher Public Library of Science
Peer Reviewed Peer Reviewed
Volume 13
Issue 7
Article Number e0201420
Keywords Captive breeding, Giant Panda, reproductive monitoring, hormone analysis,
Public URL
Contract Date Sep 19, 2018


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Copyright Statement
© 2018 Wauters et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which
permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

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