Annual Changes in Spermatozoan Production and Associated Organs of White-Tailed Deer

Abstract

The left testis and epididymis were collected from each of 60 wild adult (>12 months old) male white-tailed deer (Odocoileus virgin'anus) over approximately 1 year in southwest Virginia. Testes and epididymides were weighed separately and numbers of spermatozoa in each organ were determined. All gonadal parameters were at baseline values from February through June. Testis and epididymis weights and testicular spermatozoan numbers rose markedly from June to July. Epididymal spermatozoan numbers increased from July to August as storage of spermatozoa began. Testis and epididymis weights (g) and testicular and epididymal spermatozoan numbers (x 10) increased to maximum values (46.76 ? 8.16 S.E., 7.40 -11.11 S.E., 4.406 ?-t 0.577 S.E., and 6.602 ? 1.600 S.E., respectively) during November when does normally are bred in southwest Virginia. Male deer apparently have breeding capability and sexual libido from the latter part of September through January in the study area. However, the breeding capability of the male had begun to diminish in December as indicated by the regression of all gonadal measurements. J. WILDL. MANAGE. 41(1):92-99 Deer herds are being managed with everincreasing intensity. The primary management plan has been one directed at increasing productivity of white-tailed deer through habitat manipulation and harvest regulation. However, knowledge of the reproductive physiology of both sexes is necessary to produce optimum sustained deer yields. In particular, certain aspects of the male deer's reproductive physiology need to be known in more detail. Measurements of the testicular and epididymal spermatozoan reserves of wild deer can provide valuable data on the breeding potential of individual animals. Reliable physiological data of this type could contribute to maximization of the male deer harvest and hunter satisfaction. This research was undertaken to define more clearly the nature of reproductive changes during the annual reproductive cycle of the male white-tailed deer. We thank the personnel of the Radford Army Ammunition Plant for their cooperation during the study, and the Virginia Cooperative Wildlife Research Unit for the use of its vehicles throughout the study.