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Age determination of the nyala tragelaphus angasi



Age determination of the nyala tragelaphus angasi



South African Journal of Wildlife Research 16(3): 82-90



The tooth eruption and replacement sequence of nyala was related to age with the aid of tooth impressions from known-age animals kept in captivity, and by comparison of horn development in known-age animals with that in skulls collected. In animals with complete permanent dentition, age was examined by using wear age and cementum annuli. This pattern of molar wear in nyala, although following a negative exponential curve similar to that in impala Aepyceros melampus, zebra Equus burchelii boehmi and Grant's gazelle Gazella granti does not enable the allocation of ages to be made as clearly as in these species. Cementum annuli were found in molariform teeth and their numbers were found to increase with increasing wear age. Agreement between ages determined from cementum annuli and those determined by wear age was 51% in the case of males and 46% in females. If a range of .+-. one year is considered acceptable, the agreement is 87% in males and 67% in females. It was necessary to refer to both wear and cementum annuli to establish the age of an animal as split opaque annuli made precise counting difficult. Horn growth and changes in pelage in the males are described for their value as age criteria in free-ranging animals.

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Accession: 004688170

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