Behavioral and endocrine correlates of dominance in captive female Jackson's hartebeest (Alcelaphus buselaphus).

For species that form dominance hierarchies, such as group-living ungulates, aggressive interactions can pose a challenge to successful captive management. For example, Jackson's hartebeest (Alcelaphus buselaphus), a rare antelope of east Africa, can be difficult to maintain in captivity because aggression within female dominance hierarchies can lead to injury and death. We quantified behavioral and endocrine correlates of dominance in a captive herd of ten female hartebeest with the goal of understanding how to minimize dangerous interactions. We observed hartebeest for 18 months in a 4-ha enclosure on St. Catherines Island, Georgia. We quantified type of agonistic behavior, initiator and recipient of the behavior, who displaced whom, and age and relative size of participants. We also used fecal steroid analysis to take weekly measurements of corticoids, a hormonal correlate of stress. Hartebeest maintained a stable, linear dominance hierarchy. Only 5.9% of interactions were reversals of established rank. Most dominance interactions were low intensity, but 17.3% of interactions carried a high risk of injury (chase, horn butt, horn clash, horn clash on knees, and head push). High-ranking individuals usually initiated interactions. Most interactions were between animals of similar rank, and animals of intermediate rank participated in the highest number of interactions. The frequency of high-intensity interactions was unrelated to rank. Rank was correlated with age, but not size. There was no relationship between rank and fecal corticoid levels. Dominance interactions in hartebeest are not a function of social instability, and the frequency of dangerous interactions is not a function of rank.

Fecal steroid analysis for evaluating ovarian function in the greater kudu (Tragelaphus strepsiceros) and lesser kudu (Tragelaphus imberbis).

Seasonal reproductive-endocrine norms have not been described for the genus Tragelaphus, which consists of seven species of African antelope. Longitudinal patterns of progesterone metabolite excretion were assessed by radioimmunoassays in fecal samples collected noninvasively (three to seven samples per week) from greater kudu (Tragelaphus strepsiceros, n = 4) and lesser kudu (Tragelaphus imberbis, n = 4). Progesterone metabolite excretion patterns revealed seasonal estrous cycles in both species, and discrimination of pregnant versus nonpregnant females was achieved in lesser kudu. These data reveal the value of fecal progesterone metabolites for establishing reproductive-endocrine norms in both zoo-maintained and free-living antelopes of the genus Tragelaphus.

A simplified method for extracting androgens from avian egg yolks.

Female birds deposit significant amounts of steroid hormones into the yolks of their eggs. Studies have demonstrated that these hormones, particularly androgens, affect nestling growth and development. In order to measure androgen concentrations in avian egg yolks, most authors follow the extraction methods outlined by Schwabl (1993. Proc. Nat. Acad. Sci. USA 90:11446-11450). We describe a simplified method for extracting androgens from avian egg yolks. Our method, which has been validated through recovery and linearity experiments, consists of a single ethanol precipitation that produces substantially higher recoveries than those reported by Schwabl (1993. Proc. Nat. Acad. Sci. USA 90:11446-11450). Zoo Biol 28:137-143, 2009.

Pregnancy diagnosis in wild canids using a commercially available relaxin assay.

Accurate detection of pregnancy is a useful tool in zoo management and husbandry, conservation breeding programs and research settings. Our study evaluated the ability of a commercial relaxin hormone assay used in domestic dogs (ReproCHEK(TM)) to accurately detect pregnancy through plasma analysis in two wolf and two fox species. The relaxin assay detected all of the pregnancies greater than 25 days gestation for island foxes, fennec foxes, gray wolves, and Mexican gray wolves. For island foxes, three negative relaxin results were attributed to using the test earlier postconception than manufacturer recommendation (before day 20). Five other negative results were found for females estimated at 15-25 days gestation, spanning the early and intermediate period (21-30 days gestation) when relaxin may be detected but less reliably. There were no false-positive results in nonmated negative control animals. Relaxin assay results were highly correlated with ultrasound results and the intra-assay replicate agreement was 100%. Our results show that the ReproCHEK(TM) commercial relaxin assay is a minimally invasive and reliable method for pregnancy detection in these wild species when used after 25 days gestation and might be applied to other canids as well. Furthermore, this assay is easy to run and requires no specialized equipment, making it extremely useful for zoo and field research applications. Zoo Biol 27:406-413, 2008. (c) 2008 Wiley-Liss, Inc.

Melengestrol acetate implant contraception in addax (Addax Nasomaculatus) and Arabian oryx (Oryx Leucoryx).

Melengestrol acetate (MGA) implants were used for contraception in three addax and three Arabian oryx females housed at the Saint Louis Zoo. Serum estradiol and progesterone or fecal estrogen and progestin analysis and ultrasonography of reproductive tracts were used for monitoring changes before, during, and after MGA treatment. Follicular development and irregular uterine fluid accumulation were detected in all females during MGA treatment. Although housed with an intact male for all or most of the contraceptive period, no pregnancies occurred.One female addax may have ovulated, based on sustained elevated progesterone levels, and another showed continued follicle development, as seen by fluctuating estradiol concentrations. Reversibility was documented in two of the three addax that resumed reproductive cycles post-MGA-implant removal, whereas the third, a peripubertal female, did not cycle before, during, or after treatment. Addax females were lost to further follow-up after transfer to another institution, so the possibility of subsequent pregnancies is not known.All three Arabian oryx ovulated during the initial MGA treatment, but two of the three females had implants past the typical 2-year efficacy period. They had regular ovulatory cycles after implant removal, with mean cycle length of 27.5+/-1.5 days and mean luteal phase duration of 15.2+/-0.7 days. Reversibility was further shown in all three oryx by pregnancies after placement with a male approximately 2 years after MGA implant removal. Two produced healthy calves, but the third died owing to an unrelated terminal illness in the mother. Zoo Biol 26:299-310, 2007. (c) 2007 Wiley-Liss, Inc.

GnRH-agonist induction of fertile estrus with either natural mating or artificial insemination, followed by birth of pups in gray wolves (Canis lupus).

Although captive populations of endangered species such as the Mexican gray wolf (Canis lupus baileyi) can benefit from artificial insemination to accomplish genetic exchange, reliable techniques for timing insemination are lacking. We used the generic gray wolf (C. lupus) to test the efficacy of a short-acting GnRH-agonist implant, deslorelin, for inducing estrus. Of five females receiving implants on 17 or 18 January 2003, two mated naturally 10-17 days later, and the others were artificially inseminated using fresh semen, one on day 7 and all three on day 11. Relaxin tests revealed that one artificially inseminated female and both naturally mated females were pregnant on 1 March, and all three gave birth to healthy puppies on 4-6 April. Of the artificially inseminated females, only the one who subsequently conceived and gave birth was judged to be in cytologic estrus at the time of insemination. Two females were treated again with deslorelin on 12 January 2004, followed by collection of fecal samples for hormone analysis. One female, who was housed with a male, copulated on day 17 but did not conceive; the other was not with an adult male. Fecal progestin and estrogen profiles suggested that estrus, but not ovulation, was induced. These results indicated that deslorelin could induce fertile estrus in the gray wolf, although individual response varied. Further investigation is needed to better define and control the interval between implant insertion and ovulation for optimal timing of insemination.

Evaluation of progesterone levels in feces of captive reticulated giraffe (Giraffa camelopardalis reticulata).

Fresh fecal samples were collected from seven adult female reticulated giraffe (Giraffa camelopardalis reticulata). Samples were collected for several weeks before, during, and for a few weeks after gestation. Fecal samples were analyzed for progesterone levels by radioimmunoassay. There were significant differences in progesterone levels between pregestational and gestational samples and between gestational and postgestational samples. These results demonstrate that fecal progesterone levels are useful in determining pregnant versus nonpregnant reticulated giraffe.

XY male pseudohermaphroditism in a captive Arabian oryx (Oryx leucoryx).

A 2-yr-old Arabian oryx (Oryx leucoryx) was presented for evaluation of abnormal genitalia and infantile behavior. The oryx had a penis and a scrotum, but testes were not palpable within the scrotum or inguinal canal. The total serum testosterone for the individual was lower than in age-matched males of the same species. Surgical exploration showed markedly hypoplastic intra-abdominal gonads, which demonstrated both testicular and uterine tissue on histologic examination. After karyotype analysis, the individual was classified as an XY male pseudohermaphrodite. This condition resembles two human intersex syndromes: embryonic testicular regression syndrome and partial gonadal dysgenesis syndrome, which occur in familial lines.