Spermatozoan numbers and testicular characteristics of male white-tailed deer fawns during the mating season

Abstract

. 2000. Spermatozoan numbers and testicular characteristics of male white-tailed deer fawns during the mating season. Acta Theriologica 45: 95-102.Testicular spermatozoan numbers, testes weight, testes length, body weight, and kidney fat index (KFI) were obtained for male white-tailed deer Odocoileus virginianus (Zimmerman, 1780) fawns during the mating season at the Savannah River Site (SRS) in South Carolina. Mean values for testicular spermatozoa, testes weight, and testes length increased significantly over the study period (late October -late December) whereas body weight and KFI did not change with time. Testicular spermatozoa were found in 28% of all fawns examined and the proportion of sexually mature fawns increased greatly over the course of the study and was highest during December. These findings suggest that male fawns breed later than adults at a time that coincides with the mean conception date in doe fawns. Testes weight, testes length, body weight, and KFI were significantly greater in fawns with testicular spermatozoa compared to those without testicular spermatozoa. We suggest that testes weight is closely associated with the presence of testicular spermatozoa in fawns from SRS.

Factors influencing reproductive success in male white‐tailed deer

“…Previous research of a free ranging white‐tailed deer population in South Carolina reported that 28% of male fawns were sexually mature (Peles et al ), and a minimum of 12.5% of captive male fawns successfully bred in a study conducted in Louisiana (Schultz and Johnson ); however, breeding by young‐of‐the‐year males in our study represents, to our knowledge, the first documented occurrence of male white‐tailed deer fawns breeding in a semi‐natural environment. Although breeding by male fawns is a known possibility, the implications of our findings prompted us to more critically investigate the events.…”

“…Management for demographic conditions where prime-aged males are relatively abundant and sex ratios are balanced may contribute to the promotion of desirable sexually selected traits through increased male contest competitions; however, these effects are likely moderated in species such as white-tailed deer where annual reproduction is distributed among a relatively large proportion of males across a range of demographic conditions. Previous research of a free ranging white-tailed deer population in South Carolina reported that 28% of male fawns were sexually mature (Peles et al 2000), and a minimum of 12.5% of captive male fawns successfully bred in a study conducted in Louisiana (Schultz and Johnson 1992); however, breeding by young-of-the-year males in our study represents, to our knowledge, the first documented occurrence of male white-tailed deer fawns breeding in a seminatural environment. Although breeding by male fawns is a known possibility, the implications of our findings prompted us to more critically investigate the events.…”

“…Peles et al () reported that body mass and kidney fat index were positively associated with presence of testicular spermatozoa in fawns, which indicates that overall condition may be important in timing of puberty in male fawns. Body condition influences reproductive rates in female fawns (Sauer ), and a study conducted under relatively similar conditions reported that young male white‐tailed deer mated almost exclusively with young females (Sorin ).…”

Spermatozoan numbers and characteristics of associated organs in male white-tailed deer during the breeding season

“…1a) are decreasing during this time. In contrast, Peles et al (2000) demonstrated that testicular spermatozoan numbers of male fawns (0.29 ´ 10 9 ) are highest during December. It is important to note that spermatozoan numbers of adults and yearlings are still more than four times greater compared to fawns at this time.…”

“…Peles et al (2000) examined spermatozoan and testicular characteristics of male white-tailed deer fawns during a 9-week period in late October through December. Miller et al (1987) described changes in testosterone levels, scrotal circumference, and testes length of adults during a similar time period but did not examine spermatozoan production.…”