Endocrine milieu of perioestrus in the giant panda (Ailuropoda melanoleuca), as determined by non-invasive hormone measures

Abstract

Abstract. The aim of the present study was to determine the efficacy of faecal hormonal measures for evaluating ovarian activity in a significant sized cohort of giant pandas during the perioestrual period. Faecal excretion of oestrogen and progestagen metabolites corresponded with urinary patterns and receptive behaviours. Longitudinal assessment of 10 females revealed that, on average, faecal oestrogen concentrations started to rise (P < 0.05) above baseline (baseline meanis.e.m.; 64.7±6.6ngg~') 5 days before the preovulatory oestrogen peak (484.6=L 126.8ngg~'), which was followed by a gradual descent over 4 days to nadir. Mean faecal progestagen metabolite concentrations increased approximately twofold above baseline (from 186.2 ± 37.7 to 347.2 ± 75.7 ng g _1 ; P < 0.05) during the 20-day interval after the preovulatory oestrogen surge. Variability within and among females precluded the use of a threshold of oestrogen or progestagen metabolites to predict reproductive status, yet faeces collected 2-3 days per week provided sufficient data to recognise that an individual was in the perioestrual period. Finally, in females that were examined for at least 3 consecutive years, there was an 18-53 day variation in the onset and an 8-13 day variation in the duration of perioestrual behaviour from year to year. In summary, these findings indicate that gonadal hormone profiles associated with the period immediately before, during and after oestrus are accurately revealed by analysis of the fibrous faeces of the giant panda. This approach has potential value for providing point-in-time information on the reproductive status of free-living individuals.

Unique biphasic progestagen profile in parturient and non-parturient giant pandas (Ailuropoda melanoleuca) as determined by faecal hormone monitoring

“…Female SB473 (3.5 year old at study onset) was maintained at the SNZP (398N, 778W) and monitored in 2002, 2003, 2004 and 2005, whereas SB452 (4.5 years) was evaluated in , 2003. Females were managed as previously described (Kersey et al 2010), and records were maintained on sexual behaviours (McGeehan et al 2002), dates of attempted or confirmed copulations and/or AIs and parturition.…”

“…Annual sampling began on 1 February and ended by 4 weeks after parturition or the non-parturient interval. Each sample was placed in a labelled, resealable plastic bag, and stored at K20 8C until shipped frozen by air transport to our laboratory for processing and extraction, as previously described (Kersey et al 2010). …”

“…Faecal E metabolites were quantified using a single antibody oestrone glucuronide enzyme immunoassay (EIA; Stabenfeldt et al 1991, Kersey et al 2010. Inter-assay coefficients of variation (CV) for two internal controls (nZ83 assays) were 14.5% (mean binding, 40.0%) and 14.9% (mean binding, 74.2%), and intra-assay CV was !10%.…”

“…We recently demonstrated the ability to detect changes in oestrogen and progestagen metabolites in bamboo-laden, fibrous faeces during this species' dynamic perioestrual interval (Kersey et al 2010). Most previous endocrine studies in giant pandas have focused on behavioural oestrus and ovulation, when there appears to be a modest postovulatory rise in urinary progestagen (usually termed the primary rise; Steinman et al 2006).…”

“…Given the success of studying the dynamics of perioestrus via faecal monitoring in this species (Kersey et al 2010), we used the same approach to examine the extended (and largely ignored) post-ovulatory interval. Because faecal assessments in mammalian species generally 'dampen' the hormonal fluctuations usually measured in blood (Monfort 2003, Schwartz & Monfort 2008, we hypothesized that monitoring progestagens in faeces would provide a more accurate representation of the magnitude and temporal patterns of the primary versus secondary progestagen rise.…”