Hormonal and behavioral correlates of estrus in captive giant pandas

Abstract

Variability in female estrus expression has been identified as a barrier to captive panda reproduction [Lindburg and Millard, 1995]. In China, researchers have reported that 80% of female giant pandas in captivity exhibit ''weak estrus,'' or ''the absence of overt estrous behavior'' [Shuling et al., 1997]. Previous research on the reproductive endocrinology and behavior of female giant pandas has been limited to one to three animals, limiting understanding of the causal factors related to variable estrous expression in captive animals. In 1997 a study was initiated to evaluate the reproductive biology and behavior of one of the largest captive populations of female giant pandas in China. A checksheet was developed to track the presence or absence of 13 behavioral and physiological indices of estrus in six captive females. Daily urine samples were analyzed for estrogens and progestins by enzyme-immunoassay to determine whether ovulation took place. The behavioral and physiological indicators were aligned to the estrogen peak to examine the relationship between behavior of and ovarian hormones. Analyses of urinary ovarian hormones indicated that all females ovulated during the study. The data revealed that behavioral and physiological indices differed in their temporal relationship to ovarian hormones. Scent-marking was present 6 days before the estrogen peak, but not afterwards. Bleat and chirp vocalizations were closely associated with the estrogen peak; however, receptive behaviors, such as lordosis and ''tail up when touched,'' were most closely associated with falling estrogens. Although all females displayed some type of estrous behavior during the study, individual females varied in the presence or absence of attractive, proceptive, and receptive behaviors. Despite the variation in the behavior of individual females, the hormonal data suggest that the variability in estrous expression in this

Development and Evaluation of a Rapid Enzyme-immunoassay System for Measurement of the Urinary Concentration of Estrone-3-glucuronide in a Female Giant Panda (Ailuropoda melanoleuca)

“…Since the peak concentrations of urinary E1G were not associated with the frequency and duration of presenting behavior during the 6 consecutive estrous seasons, the estrous behavior in the female giant panda appeared to be influenced not only by the estrogen concentrations but also by environmental circumstances, including the presence of a sexually mature male. This result may be somehow comparable to the ram effect reported by Rosa et al [25]; basically, the presence of a sexually mature ram is the key to inducing estrus and ovulation in anestrous ewes.In giant pandas, "tail up" behavior, defined as presenting behavior in our study, was observed from Day -1 until Day 5 (Day 0=day on which the urinary concentration of E1G reached a peak) [21]. Murata et al [26] demonstrated that the female presents estrous behavior in the presence of a male 1 day after the urinary estrogen concentration reaches a peak.…”

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

“…This interval was then followed by a distinctive 3-to 20-fold elevation that lasted another 28-63 days before declining to signal birth or the end of a non-parturient phase. A general biphasic progestagen pattern has been reported from earlier urinary monitoring studies of this species, but only in a few individuals (Hodges et al 1984, Chaudhuri et al 1988, Masui et al 1989, Monfort et al 1989, Mainka et al 1990, McGeehan et al 2002, Narushima et al 2003. The present study was important because of the increased confidence generated from simultaneously examining a large cohort of giant pandas, some of which were observed year to year.…”

“…For years, a compliment of non-invasive tools has been used to approximate the reproductive status of female giant pandas in ex situ collection, including through behavioural observations (Czekala et al 1998, McGeehan et al 2002, urinary hormone quantification (Steinman et al 2006), visual changes of the vulva (McGeehan et al 2002), vaginal cytology and/or ultrasonography in cooperative individuals (Sutherland-Smith et al 2004, Zhang et al 2009). Urinary progestagen monitoring has been especially useful for tracking pregnancy (or pseudopregnancy) of captive mated and/or artificially inseminated females.…”

“…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.…”

“…There has been little attention directed at understanding the prolonged luteal phase in pregnant versus non-pregnant individuals. Of ten reports on this topic, only three giant pandas in total have been monitored for urinary progestagen profiles from ovulation to parturition or through a non-parturient phase (sometimes referred to as 'pseudopregnancy'; Bonney et al 1982, Hodges et al 1984, Chaudhuri et al 1988, Masui et al 1989, Monfort et al 1989, McGeehan et al 2002, Narushima et al 2003, Dehnhard et al 2006, Steinman et al 2006, Spady et al 2007. In these cases, a secondary urinary progestagen rise has occurred 74-122 days after the end of oestrus (Steinman et al 2006) that has suggested a shift in hormonal source, perhaps related to nidation.…”