Characterization of Longitudinal Fecal Steroid Hormone Profiles in Captive Chinese Goral (Naemorhedus griseus)

Abstract

To date, there is no information on reproductive or stress hormone activity of Chinese goral (Naemorhedus griseus), a threatened species that is part of captive breeding management for reintroduction in Thailand. The purposes of the present study were to: 1) determine the influence of season on testicular, ovarian, and adrenal steriodogenic activity; 2) examine the relationship between gonadal hormone excretion and sexual behaviors throughout the year; and 3) determine the impact of gender, season, and management on goral adrenal activity. Fecal samples were collected 3 - 7 days/week for 15 months from eight adult males and females housed at Omkoi Wildlife Sanctuary (Omkoi) in Thailand, and observations of sexual behaviors and breeding were conducted each morning for 30 minutes/session in each gender. Additionally, fecal samples were collected 3 days/ week for 1 year from 63 individuals (n = 32 males, 31 females) at two facilities: Omkoi, an off-exhibit breeding center that housed goral in individual pens (16 pens; n = 8 males, 8 females) and in small family groups (8 pens; n = 8 males, 8 females); and the Chiang Mai Night Safari (NS), a zoo that maintained 31 goral (n = 17 males, 14 females) in one large pen. All samples were analyzed for steroid metabolites using validated enzyme immunoassays. Mean androgen metabolite concentrations were greater (P < 0.05) during the rainy season and winter compared to the summer, which were related to male sexual behaviors including flehmen, tongue flick, approach and breeding activity. Based on concentration of fecal estrogen and progestagen metabolites, the overall estrous cycle length was about 23 days, with a 2- to 3-day follicular phase and an 17- to 25-day luteal phase. Female sexual behaviors, most remarkably tail-up, increased for 2 - 3 days during the estrous period, when the estrogens were elevated. Fecal progestagens were elevated during luteal phases, and increased during gestation, which averaged approximately 7 months. The lactation period was about 5 months, and females were anestrus for 2 - 5 of those months, with the exception of one that cycled continuously throughout the study period. Two females were conceived approximately 2 months postpartum, and so were pregnant during lactation. Birth records over the past 21 years indicated that calves were born throughout the year. This combined with the hormonal patterns suggested that female goral are not strongly seasonal, at least in captivity, although there was considerable variation in estrogen and progestagen patterns among individuals. Glucocorticoid metabolite levels were greater in male than female goral at Omkoi throughout the year, and there was a seasonal effect on adrenal activity (P < 0.05). Goral at Omkoi and NS were used to assess the effect of animal density on fecal glucocorticoid concentrations, and overall, the greatest levels were found at NS (n = 31 adults/pen; 27 m2 per animal) compared to Omkoi (n = 2 adults/pen; 400 m2 per animal) (P < 0.05). In summary, this is the first study to evaluate endocrine function in goral, and results showed seasonal variation in testicular, ovarian and adrenal steroidogenic function, with greater activity in the rainy season and winter. Given that resource availability for captive male and female goral are consistent throughout the year, reproduction may be regulated primarily by photoperiod. Additionally, gender, season and animal density also had significant effect on adrenal steroidogenic activity. Potential stressors relating to the welfare were identified, which will guide future efforts to develop management. In conclusion, fecal steroid metabolite monitoring is an effective means of evaluating gonadal and adrenal function in goral and will be a useful tool for improving breeding management, planning development of assisted reproductive techniques, developing healthy populations, and creating self-sustaining.