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Dubbo, Australia

Burgess E.A.,University of Queensland | Lanyon J.M.,University of Queensland | Keeley T.,Taronga Western Plains Zoo
Reproduction | Year: 2012

Knowledge of male reproductive status and activity in free-ranging animals is vital to understanding reproductive patterns and population dynamics. Until now, almost all information regarding reproductive behavior of the dugong, a cryptic marine mammal, has relied on post-mortem examination. We examined the relationships between body length, tusk eruption (secondary sexual characteristic), seasonality, and group association on fecal testosterone metabolite concentrations in 322 free-ranging dugongs (159 males, 163 females) in subtropical Moreton Bay, Australia. Fecal testosterone concentrations demonstrated biologically meaningful differences in testicular activity between sexes and across reproductive/age classes, and were correlated with circulating concentrations in serum. Male dugongs have a pre-reproductive period that persists until a body length of 240 cm is achieved. Puberty apparently occurs between 240 and 260 cm body length when fecal testosterone levels increase fourfold (O500 ng/g) over juvenile levels, and is associated with tusk eruption. However, social maturity may be delayed until male dugongs are larger than 260 cm with well-developed tusks. In mature males, the lowest (!500 ng/g) fecal testosterone concentrations occur in the austral autumn months with maximal concentrations in September-October, coincident with the onset of a spring mating season. During spring, solitary mature males had fecal testosterone concentrations double those of mature males sampled within groups, potentially suggesting a mating strategy involving roving of reproductively active males. This study demonstrates that single-point physiological data from individuals across a population have value as indicators of reproductive processes. Our approach provides an efficacious non-lethal method for the census of reproductive status and seasonality in live male dugongs. © 2012 Society for Reproduction and Fertility.

Burgess E.A.,University of Queensland | Blanshard W.H.,Sea World | Barnes A.D.,Sea For Life | Gilchrist S.,Sea For Life | And 3 more authors.
Animal Reproduction Science | Year: 2013

Determining the reproductive status of long-term captive animals is essential because the onset of sexual maturity and reproductive activity may necessitate changes in husbandry requirements. This study reports on the first multi-year reproductive hormone monitoring program for captive dugongs of both sexes using feces. Fecal samples were collected from one male ( Pig) over 9 years (4-13.2. y of age; n=288 samples, 0.8. ±. 0.1 samples per week from July 2007 to February 2012) and one female ( Wuru) over 7 years (from neonate to 6.9 y; n=171 samples, 0.5. ±. 0.1 samples per week from July 2007 to February 2012), and from one solitary female dugong ( Gracie) over 10 months (10.5-11.3. y of age; n=54 samples, 1.1. ±. 0.2 sample per week from September 2008 to June 2009). Using enzyme-immunoassay, fecal progesterone (fP) and estradiol-17β (fE) concentrations were assayed in the two captive females, and testosterone (fT) concentration in the captive male, and compared these to concentrations in wild dugongs. Female Wuru exhibited increasing fP concentrations at 5+ y, indicating early onset of ovarian cycling typical of non-pregnant adult females. Female Gracie maintained basal fP concentrations consistent with wild immature dugongs, indicating that she had not reached puberty by 11. y. Nutritional plane may account for differences in age at sexual maturity in these female dugongs. At age 3-4. y, Wuru had fE concentrations 1.4 times greater than maximum concentrations recorded in all wild females, and these concentrations were coincident with a period of rapid weight gain. For the male Pig, increasing fT concentrations at 9. y provided early indications of puberty. Pig's tusks erupted by 11. y, and sexual maturity (indicated by spermatic semen) was confirmed by 12.8. y. Identification of sexual maturation prompted two trials of a male contraceptive treatment using the GnRH agonist, deslorelin (9.4. mg administered in 2010 and 15.6. mg in 2011). Testosterone production was not significantly suppressed by these dosages, and treatment did not terminate sperm production at week 10-11 post-implantation, even at the larger dose tested. Routine analysis of fecal hormones was helpful for making reproductive management decisions regarding individual captives and in guiding the long-term captive management of this cryptic species. © 2013 Elsevier B.V.

Burgess E.A.,University of Queensland | Lanyon J.M.,University of Queensland | Brown J.L.,Smithsonian Conservation Biology Institute | Blyde D.,Sea World Australia | Keeley T.,Taronga Western Plains Zoo
General and Comparative Endocrinology | Year: 2012

Assessing reproductive status and monitoring reproductive rates is important in the effective management of vulnerable marine mammal species such as the dugong (Dugong dugon). Knowledge of the reproductive physiology of this species is limited, and determining reproductive parameters (e.g., sexual maturation, pregnancy, and reproductive senescence) has been restricted by a lack of non-lethal methods for assessing reproductive status in free-ranging individuals. The aim of this study was to develop a method to identify pregnant individuals in a wild dugong population. Using an enzymeimmunoassay, we quantified concentrations of fecal progesterone metabolites (fP) in 322 dugongs, including confirmed pregnant females (n= 10), presumed non-pregnant adult females (n= 25), juvenile females (n= 24), subadult females (n= 41), adult females of unknown pregnancy state (n= 63), and males of all sizes (n= 159). External body morphometrics of each dugong were measured, and confirmation of pregnancy in adult female dugongs was determined by ultrasonography or observation of subsequent neonates. Concentrations of fP were different between sexes and reproductive size classes (P< 0.001), and ∼30-fold higher in confirmed pregnant dugongs (2017-7760. ng/g) compared to presumed non-pregnant females (30-221. ng/g), juvenile females (29-195. ng/g), and males (24-261. ng/g) (P< 0.001). Body measures of maximum and anal girths, and teat length were all greater in confirmed pregnant females than presumed non-pregnant females (all P< 0.05). We evaluated a Discriminant Function Analysis (DFA) to provide a model for predicting pregnant and non-pregnant dugongs. Cross-validated results showed that the DFA correctly classified 100% of pregnant and non-pregnant females using fP concentrations, body length, fineness ratio (an index of body shape), and teat length (a female reproductive trait). Using the DFA model, we classified the pregnancy status of all female dugongs and identified a total of 30 females as pregnant and 133 females as non-pregnant from the sampled population over the sample period. Pregnant dugongs in the Moreton Bay population are characterized by fecal progesterone metabolite concentrations > 1000. ng/g, body length ≥ 260. cm, maximum girth ≥ 215. cm, anal girth ≥ 126 cm, and teat length ≥ 5 cm long. In summary, analysis of fP concentrations in combination with body morphometrics may be used to diagnose pregnancy in free-ranging dugongs, and provides a new tool to monitor breeding rates of wild sirenian populations. © 2012 Elsevier Inc.

Portas T.,Taronga Western Plains Zoo | Portas T.,University of New South Wales | Evans G.,University of New South Wales | de Graaf S.,University of New South Wales
Animal Reproduction Science | Year: 2012

The seminiferous cycle of the rhinoceros was investigated for the first time using testicular tissue from captive white (Ceratotherium simum, n= 2) and black (Diceros bicornis, n= 1) rhinoceroses. Stages of the seminiferous epithelial cycle were characterised using the tubular morphology method and relative frequencies of each stage determined. This method allowed for the identification of eight stages of cellular associations characteristic of the seminiferous cycle in white and black rhinoceroses. The eight stages of the seminiferous cycle observed closely approximated the stages previously described for the domestic horse (Equus caballus). Premeiotic (stages I-III), meiotic (stage IV) and postmeiotic (stages V-VIII) represented 44.8%, 5.3% and 49.9% of the seminiferous cycle respectively. © 2012 Elsevier B.V.

Hogan L.A.,University of Queensland | Johnston S.D.,University of Queensland | Lisle A.T.,University of Queensland | Keeley T.,Taronga Western Plains Zoo | And 4 more authors.
Applied Animal Behaviour Science | Year: 2011

The response of animals to handling by humans has been extensively evaluated in domesticated livestock, but rarely examined in wildlife species. Twelve captive wombats (Lasiorhinus latifrons) were subjected to two treatments in a replicated design: (1) daily handling, involving 15 min of tactile contact 5 d/wk for 12 wk and (2) no-handling, involving no contact apart from that received during routine husbandry. The effect of handling was assessed via overt responses to human approach and touch, a stressor, and a novel stimulus. Daily handling reduced the wombat's flight distance in response to human approach; more in the first handling replicate (-0.16 ± 0.02 m/wk) than in the second (-0.06 ± 0.02 m/wk). A behavioural reactivity score also declined faster in the first than second handling replicate. Synthetic ACTH was used to validate the measurement of faecal cortisol metabolites in L. latifrons by EIA. Faecal cortisol metabolite secretion consistently increased in reaction to a handling procedure involving forced human contact (indicating a lack of habituation) but the magnitude of this response was not reduced by regular handling. Regular handling therefore changed the human-wombat relationship by lowering reactivity to and avoidance of the human handler, but did reduce the stress response, suggesting that the wombats entered into a state of learned helplessness. © 2011 Elsevier B.V.

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