The Validity of the Wear-Age Technique for Alberta Pronghorns

Abstract

The incisor (Pil) teeth of 190 mature pronghorn antelopes (Antilocapra americana) collected betsZeen 1961 and 1964 in Alberta were histologically prepared and examined for the presence and number of cementum annulations. The ages of animals determined by this method were compared with those assigned previously on the basis of a wear-age technique. The percentage of agreement between these two methods ranged from 69.2 percent in the 3.S-year class, to 50.0 percent in the 7.5-year class. The overall agreement for all age-classes (2.S8.5 years) was 60.9 percent. 0f the animals misclassified using the wear-age technique, 68.1 percent were underaged. Examination of the cementum annuli of histologically prepared teeth provided a more reliable inteIpretation of age than the examination of teeth prepared by standard cutting and grinding techniques. For pronghorns in Alberta the sZear-age technique is not a valid management tool. WEAR_AGE TECHNIQUE FOR PRONGHORNS * Kerwin and Mitchell 743 PURSER, D. B., AND R. J. MOIR. 1966. Dietary effects upon concentrations of protozoa in the rumen. J. Animal Sci. 25(3):6674. , T. J. KLOPFENSTEIN, AND J. H. CLINE. 1966. Dietary and defaunation effects upon plasma amino acid concentrations in sheep. J. Nutrition 89 ( 2 ): 22S234. ULLREY, D. E., W. G. YOUATT, H. E. JOHNSON, P. K. KU, AND L. D. FAY. 1964. Digestibility of cedar and aspen browse for the white-tailed deer. J. Wildl. Mgmt. 28(4):791-797. , , , L. D. FAY, B. L. SCHOEPKE, AND W. T. MAGEE. 1970. Digestible and metabolizable energy requirements for winter maintenance of Michigan white-tailed does. J. Wildl. Mgmt. 34 ( 4 ): 86S86g, H. E. JOHNSON, W. G. YOUATT, L.D. FAY, B. L. SCHOEPKE, AND W. T. MAGEE. 1971. A basal diet for deer nutrition research. J. Wildl. Mgmt. 35( 1 ): 57-62. VAN HORN, H. H., C. F. FOREMAN, AND J. E. ROD_ RIGUEZ. l9B7. Effect of high-urea supplementation on feed intake and milk production of dairy cows. J. Dairy Sci. 50(S):709-714. VAN SOEST, P. J. 1963. USe 0 detergents in the analysis of fibrous feeds. II. A rapid method for the determination of fiber and lignin. J. Assoc. Official Agr. Chemists 46(S):829-835. , AND R. H. WINE. 1967. Use of detergerlts in the analysis of fibrous feeds. IV. Determination of plant cell-wall constituents. J. Assoc. Official Anal. Chemists 50 ( 1 ): 50-55. Received for publication January 29, 1971. The ability to determine the age structure of a population accurately, either by direct examination of living animals or from animals killed by hunters, is a necessary prerequisite for any study of the dynamics of that population. To meet this requirement, three age-classification techniques have been applied to pronghorns: (1) the sequence of tooth eruption and wear ( Dow and Wright 1962 ); ( 2 ) the weight of the eye lens ( Kolenosky and Miller 1962 ); and ( 3 ) the number of cementum annulations of incisor teeth ( McCutchen 1966, 1969). These techniques have also beerl applied to other ungulates, but until recently there have been few repcxrts comparing the accuracies of these methods. Our study evaluates the accuracy of the wear-age method used for Alberta pronghorns. In addition, the use of a histological technique in the preplaration of the incisors is compared with the cutting and grinding method used previously for antelopes ( McCutchen 1966, 1969 ) . We acknowledge the advice and assistance of R. Y. Zacharuk and H. E. Mann, This content downloaded from 157.55.39.210 on Sat, 30 Jul 2016 06:10:57 UTC All use subject to http://about.jstor.org/terms