1) General Zoological Data
Among the genus Tragelaphus (from Gr. tragos=he-goat, and elaphos=deer) with six species of the subgenus Tragelaphus, the bongo is the only member of the subgenus Boocerus. Occasionally, Boocerus eurycerus (eurus=broad, and keras=horn) is used as its species designation. This beautiful, large, striped brown East African antelope may weigh up to 220 kg. Males are significantly darker than females, and both sexes have slightly spiraled horns. It lives in dense forested regions (hence "Woodbucks") and is a browsing animal that makes up occasionally sizeable groups. The estrous cycle is described as being 21-22 days, with estrus lasting 3 days. The gestational length is between 282 and 287 days long, with single offspring weighing 18-22 kg born. First pregnancy is described as occurring at 27 months, and the longevity in captivity is 19+ years. Two subspecies are listed by Nowak (1999). Numerous animals are being bred well in several zoological gardens, including the San Diego Zoo. Although the animal is not endangered, it is not frequently seen. The relation between the Tragelaphinae was studied with an evaluation of the cytochrome b gene (Matthee & Robinson, 1999). These authors found no justification for the generic status of Boocerus. Ralls (1978), who published a detailed review of this species, stated that no direct antecedent to this species is known from the fossil record. She suggested that it represents a recent lineage of tragelaphines. Tragelaphinae may have derived from presumed common ancestors with the nilgai and may subsequently have immigrated to Africa from Asia. Their ultimate origin is still disputed, however. Speculations and recent findings are summarized by Thenius (1969). Petit et al. (1994) have constructed a putative phylogeny from their cytogenetic findings. As many other species of African antelopes, bongos have an unusual chromosomal structure. Tragelaphines possess a fusion between the Y-chromosome and a common (#13) autosome.
|Pair of bongos at San Diego Zoo.|
|Front view of female bongo.|
General Gestational Data
Characterization of the Placenta
|Delivered bongo placenta, maternal aspect. Note the four rows of cotyledons.|
|Another bongo placenta, more elongate and showing cotyledons with much different colors (stillbirth).|
|Higher magnification of the cotyledons with congestion and other without blood.|
|Amnionic surface of this stillborn's placenta with numerous finely granular, yellow, areas of squamous metaplasia.|
|Single cotyledon of delivered term bongo placenta with chorionic surface.|
|Cross-section of cotyledonary surface of term bongo placenta. Moderate branching of villi is evident.|
|Term bongo placental surface villous architecture.|
Details of fetal/maternal barrier
|Higher magnification of trophoblastic surface of the villi. The binucleate cells are labeled, as are the fetal capillaries.|
|Moderate magnification of term villous structure of bongo placenta.|
|Villous branching of term bongo placenta.|
|Portion of bongo umbilical cord with large allantoic vessel above, numerous small vessels and the allantoic duct.|
|Membranes with amnion and allantois.|
Trophoblast external to barrier
|This is the opened uterine horn of a neonatal Bongo that displays the abundance of endometrial "caruncles" as yellow-green elevations.|
|Histology of fetal uterus with caruncles at "C" and myometrium at "M".|
|This putative phylogeny is arranged according to cytogenetic information with chromosome numbers (2n=males/females) and the types of fusions as arranged according to bovid karyotype agreement.|
hybrids with the sitatunga (Tragelaphus spekei) have been described
from the Antwerp zoo (Gray, 1972). Their gestation lasted 309 days and Cesarean
section was necessary for delivery. One female hybrid produced a female
offspring when mated with a male sitatunga.
remarks - What additional Information is needed?
Bent, N. and Reason, R.: A preliminary study of sex ratios in captive=-born ruminants. Int. Zoo Yb. 36:223-228, 1998.
Bush, M., Montali, R.J., Gray, C.W. and Neeley, L.M.: Cesarean section in a Bongo antelope. J. Amer. Vet. Med. Assoc. 163:552-553, 1973.
Doi, S., Shifrin, S., Santisteban, P., Montali, R.J., Schiller, C., Bush, M. and Grollman, E.F.: Familial goiter in bongo antelope (Tragelaphus eurycerus). Endocrinology 127:857-864, 1990.
B.L.: Embryo transfer in exotic bovids. Intern. Zoo Yearbook 24-25:138-142,
Gray, A.P.: Mammalian Hybrids. A Check-list with Bibliography. 2nd edition. Commonwealth Agricultural Bureaux Farnham Royal, Slough, England, 1972.
Haigh, J.C.: The immobilization of bongo (Boocerus eurycerus) and other African antelopes in captivity. Vet. Rec. 98:237-239, 1976.
Heldstab, A. and Ruedi, D.: The occurrence of myodystrophy in zoo animals at the Basle Zoological Garden. Pp. 27-34, In, The Comparative Pathology of Zoo Animals, R.J. Montali and G. Migaki, eds., Smithsonian Institution Press, Washington, D.C., 1980.
Hradecky, P., Benirschke, K. and Stott, G.G.: Implications of the placental structure compatibility for interspecies embryo transfer. Theriogenology 28:737-746, 1987.
Hradecky, P., Mossman, H.W. and Stott, G.G.: Comparative histology of antelope placentomes. Theriogenology 29:693-714, 1988.
Hradecky, P., Mossman, H.W. and Stott, G.G.: Comparative development of ruminant placentomes. Theriogenology 29:715-729, 1988.
Kirkwood, J.K., Wells, G.A., Cunningham, A.A., Jackson, S.I., Scott, A.C., Dawson, M. and Wilesmith, J.W.: Scrapie-like encephalopathy in a greater kudu (Tragelaphus strepsiceros), which had not been fed ruminant-derived protein. Vet. Rec. 130:365-367, 1992.
Kirkwood, J.K., Cunningham, A.A., Austin, A.R., Wells, G.A. and Sainsbury, A.W.: Spongiform encephalopathy in a greater kudu (Tragelaphus strepsiceros) introduced into an affected group. Vet. Rec. 134:167-168, 1994.
Matthee, C.A. and Robinson, T.J.: Cytochrome b phylogeny of the family Bovidae: resolution within the alcelaphini, antilopini, neotragini, and tragelaphini. Mol. Evol. 12:31-46, 1999.
Nowak, R.M.: Walker's Mammals of the World. 6th ed. The Johns Hopkins Press, Baltimore, 1999.
Petit, P., Vermeesch, J.R., Marynen, P. and de Meurichy, W.: Comparative cytogenetic study in the subfamily Tragelaphinae. Proc. 11th Europ. Coll. Cytogenet. Domest. Anim. Pp. 109-113, 1994/5.
Pospisil, J., Kase, F., Vahala, J. and Mouchova, I.: Basic haematological values in antelopes - II. The hippotraginae and the tragelaphinae. Comp. Biochem. Physiol. A 78:799-807, 1984.
Ralls, K.: Tragelaphus eurycerus. In, Mammalian Species, No. 111, 1-4, 1978. Amer. Soc. Mammal.
Schiller, C.A., Montali, R.J., Doi, S. and Grollman, E.F.: Clinical and morphologic findings of familial goiter in bongo antelope (Tragelaphus eurycerus). Vet. Pathol. 32:242-249, 1995.
Thenius, E.: Stammesgeschichte der Säugetiere (einschliesslich der Hominiden). In Handbuch der Zoologie, J.G. Helmcke, D. Starck and H. Wermuth, eds. Vol. 8/2:369-722, 1969, Walter de Gruyter & Co., Berlin.
Wallace, C.: Chromosomal evolution in the antelope tribe Tragelaphini. Genetica 48:75-80, 1978.
Wurster, D.H.: Sex-chromosome translocations and karyotypes in bovid tribes. Cytogenetics 11:197-207, 1972.
Xanten, W.A. Jr.: Gestation period in the bongo (Boocerus eurycerus). J. Mammal. 53:232, 1972.
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