Seasonality affects semen cryopreservation of white-tailed deer bucks (Odocoileus virginianus)

Abstract

White-tailed deer farming is a growing industry in the United States, with breeding operations contributing significantly to the industry’s economic impact. Artificial insemination with frozen semen allows for selection and dissemination of valuable genetics, yet surprisingly little information is available regarding the best time throughout rut to perform semen cryopreservation. The objective of this study was to compare the efficacy of semen cryopreservation of white-tailed deer bucks collected early in the breeding season (September), at peak rut (December), and late season (March). We hypothesized that semen freezing ability would be enhanced at peak rut. Mature bucks (n = 7-11) were anesthetized with tiletamine-zolazepam (0.88 mg/kg) and xylazine (2.2 mg/kg) administered intramuscularly via projector. The penis was manually exteriorized, and semen was collected by electroejaculation (Pulsator IV, Lane Manufacturing, Inc). An aliquot of the ejaculate was diluted 1:60 in warm (37°C) Optixcell extender (IMV Technologies) and placed into a pre-warmed 20 µM chamber slides (Vitrolife, Microcell Counting Chambers) for assessment of motility via computer-automated sperm analysis (Spermvision II, MiniTube of America).