Fecal Steroid Assays for Assessing Reproductive-Endocrine Function in the Genus Tragelaphus
The genus Tragelaphus has been minimally investigated in terms of its reproductive endocrinology. Studies on this genus to date have focused on serum, which carries more risk in animal handling than noninvasive endocrine methods.3,4 Additionally, no studies have been performed to establish normative annual reproductive parameters in these species. This study investigated fecal hormone parameters in multiple species in the genus: greater kudu (Tragelaphus strepsiceros), bongo (T. eurycerus), sitatunga (T. spekii), lesser kudu (T. imberbis), and nyala (T. angasii). Fecal samples were collected serially from both males and females for 1–12 months from each animal. Samples were collected a minimum of three times per week for females and once per week for males. Fecal extracts were assayed using enzyme immunoassay (EIA) and selected samples were further assayed using radioimmunoassay (RIA). Hormones validated and tested using EIA were progestins, estradiol, and testosterone. Progesterone was validated and tested using RIA.
Despite methodic validation (parallelism to standard curve, linear recovery, and high-pressure liquid chromatography), fecal progestins measured using EIA did not yield clear estrous cyclicity. Early pregnancy (confirmed by later birth) was also not clearly demonstrated. By contrast, RIA was able to detect seasonal estrous cycle changes. While non-specific fecal progestins have been successfully employed to monitor annual reproductive parameters in other members of the family Bovidae, specifically the subfamilies Hippotraginae and Antilopinae, they do not appear to be effective for the genus Tragelaphus.1,2,5,6 Instead, more specific progesterone assays seem to be of greater benefit.
The authors wish to thank Niki Presley and the laboratory staff of the Conservation and Research Center, the laboratory staff at the St. Louis Zoo, the animal care staff and keepers at Como Zoological Garden and the St. Louis Zoo, and the staffs of all the participating institutions.
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