104 Teratospermia in tigers: Evidence for declining sperm quality over time

Ejaculate traits in male tigers (Panthera tigris) were studied in the 1980s, but little work has been done on male tigers since then and the reproductive status of the current zoo population is not known. In order to characterise ejaculate traits in male tigers, semen was collected by electroejaculation (90 to 100 stimulations, 3 to 7V), subjected to a standard semen analysis (volume and pH and sperm concentration, motility, and morphology), and cryopreserved. To date, semen has been collected from 24 males (n=16 Amur tigers, Panthera tigris altaica, 10.3±1.1 y; n=7 Sumatran tigers, Panthera tigris sumatrae, 9.4±1.3 y; n=1 Malayan tiger, Panthera tigris jacksoni, 6 y), maintained at 18 USA institutions. Ejaculates (4.7±0.6 mL; pH=8.4±0.1) contained 240.3±54.9×106 spermatozoa, which yielded 357 straws of cryopreserved spermatozoa that were used to establish a Tiger Genome Resource Bank. The majority of the spermatozoa were motile (69.2±4.6%), but the proportion of spermatozoa exhibiting normal morphology was very low (18.7±3.3%) and similar between both Amur (20.0±4.8%) and Sumatran (16.3±5.2%) males, with the majority of abnormalities affecting the midpiece (retained cytoplasmic droplets, bent midpieces, or both). Previous studies of male tigers that utilised comparable anaesthesia regimens and collection techniques recovered similar quantities of semen (5 to 10mL), but the proportions of normal spermatozoa in those studies (>65%) were very high (Wildt et al. 1988 Biol. Reprod. 38, 245; Byers et al. 1990 J. Reprod. Fert. 90, 119). Proportions of normal spermatozoa in the current study more closely resemble those reported for the teratospermic (<40% normal spermatozoa) clouded leopard (Neofelis nebulosa, 18.5% normal spermatozoa, Pukazhenthi et al. 2006 Theriogenology 66, 1790) and cheetah (Acinonyx jubatus, 18.4% normal spermatozoa, Crosier et al. 2007 Reprod. Fertil. Dev. 19, 370), as well as the South China tiger (Panthera tigris amoyensis, 27% normal spermatozoa). The number of spermatozoa per ejaculate was also decreased in Amur tigers (190.1±67.7×106) compared to Sumatran tigers in the current study (362.9±99.5×106) and earlier studies of other Amur tigers (>500×106). The reasons for this apparent decline in sperm quality are unclear, but reduced proportions of normal spermatozoa have been associated with reduced heterozygosity in small, isolated populations of felids (Florida panthers, South China tigers) or species that have been through a genetic bottleneck (cheetahs). Semen collections and evaluations will continue in order to determine if trends for compromised sperm quality are representative of the current SSP population(s) or an artifact of our reduced sample size. Additional studies investigating possible environmental, genetic, or nutritional influences on sperm morphology are also warranted. This work is supported by grants from Association of Zoo and Aquarium’s Conservation Grants Fund and Point Defiance Zoo and Aquarium’s Dr. Holly Reed Conservation Fund.

Validating faecal glucocorticoid metabolite analysis in the Virunga mountain gorilla using a natural biological stressor

The continued degradation of primate habitat worldwide is forcing many primate populations into small protected forest islands surrounded by high-density human populations. One well-studied example is the critically endangered mountain gorilla (Gorilla beringei beringei). Decades of monitoring and research on Rwanda's mountain gorillas offer a unique opportunity to use non-invasive endocrine analysis to address pressing questions about the conservation of this endangered population. The aims of our study were as follows: (i) to validate field and laboratory methods for assessing stress through faecal glucocorticoid metabolite (FGM) analysis using inter-social unit interactions as a natural stressor; (ii) to determine the excretion lag times between interactions and detectable stress response in faeces; and (iii) to determine whether there are circadian patterns of FGM excretion. We collected ~6000 faecal samples from 127 known gorillas in 10 habituated groups, monitored by the Dian Fossey Gorilla Fund's Karisoke Research Center over 21 months in 2011 and 2012. Extracted FGMs were measured using a cortisol enzyme immunoassay (R4866; C. J. Munro). Results revealed cause-effect relationships between inter-unit interactions and increased FGMs (relative to individual pre-event samples) between 20 and 140 h after interactions, with the peak most often occurring on day 3. There was no evidence of circadian patterns in FGM concentrations, as previously shown in many species with long gut passage times. However, baseline FGM concentrations were lower in adult males than in adult females, and variation was associated with the collection month, indicating possible seasonal variation. This study provides a biologically validated, field-friendly faecal hormone metabolite extraction and laboratory enzyme immunoassay analysis method for non-invasive monitoring of adrenocortical activity in Virunga mountain gorillas. The methods are useful for future evaluation of a variety of environmental and human-induced potential stressors in this critically endangered population.