Department of Veterinary Clinical Medicine, College of Veterinary Medicine, University of Illinois Urbana-Champaign, Urbana, IL, 61802, United States.
Department of Veterinary Clinical Medicine, College of Veterinary Medicine, University of Illinois Urbana-Champaign, Urbana, IL, 61802, United States.
Theriogenology. 2018 Jul 1;114:308-316. doi: 10.1016/j.theriogenology.2018.04.015. Epub 2018 Apr 12.
White-tailed deer farming is a growing industry in the United States, yet there is still a need to improve breeding practices in captive cervids. The objective of this study was to compare reproductive and somatic characteristics of white-tailed bucks early in the breeding season (September), at peak rut (December), and late breeding season (March). We hypothesized that reproductive parameters would improve at the peak of the breeding season. Young, mature bucks (n = 7-11, ages 2-3 yr) were anesthetized via projector with tiletamine-zolazepam and xylazine. Semen was collected by electroejaculation and evaluated for sperm output, motility, and morphology. The bulbourethral, vesicular, and prostate glands were measured by transrectal ultrasound. Body condition score, thoracic circumference, rump fat thickness, scrotal circumference, and testicular measurements were also recorded. Serum testosterone, estradiol, and IGF-I concentrations were measured. Body condition score and rump fat thickness were highest in September, intermediate in December, and lowest in March (p < 0.01), whereas thoracic circumference was lowest in September (p = 0.02). In September, serum IGF-I was highest (p < 0.01) and estradiol was lowest (p ≤ 0.02). Serum testosterone levels were lowest in March and highest in December (p < 0.01). Testicular volume and scrotal circumference were highest in September, intermediate in December, and lowest in March (p < 0.01). Bulbourethral gland length was greatest in March (p ≤ 0.05), whereas prostate length was greatest in September (p ≤ 0.02). Vesicular gland length and width were highest in December, intermediate in September, and lowest in March (p ≤ 0.02). Both overall and progressive sperm motilities were lowest in March (p < 0.01), but did not differ between September and December (p ≥ 0.12). In December, bucks had the highest percentage of normal sperm and lowest percentage of primary sperm defects (p ≤ 0.01). Collectively, our results demonstrated variation in reproductive and metabolic characteristics of white-tailed deer bucks throughout the breeding season at 40°N. The physiological variations described here will be useful for veterinarians and researchers performing reproductive evaluations in white-tailed deer bucks.
白尾鹿养殖是美国一个不断发展的产业，但在圈养有蹄类动物的繁殖实践中仍需要改进。本研究的目的是比较白尾鹿公鹿在繁殖季节早期（9 月）、高峰期（12 月）和繁殖后期（3 月）的繁殖和体况特征。我们假设繁殖参数在繁殖高峰期会有所改善。年轻的、成熟的雄鹿（n=7-11，年龄 2-3 岁）通过肌松剂混合物替来唑仑和二甲苯胺进行麻醉。通过电刺激采集精液并评估精子产量、活力和形态。通过直肠超声测量尿道球腺、精囊和前列腺的大小。还记录了体况评分、胸围、臀部脂肪厚度、阴囊周长和睾丸测量值。测量血清睾酮、雌二醇和 IGF-I 浓度。9 月体况评分和臀部脂肪厚度最高，12 月次之，3 月最低（p<0.01），而 9 月胸围最小（p=0.02）。9 月 IGF-I 最高（p<0.01），雌二醇最低（p≤0.02）。3 月血清睾酮水平最低，12 月最高（p<0.01）。睾丸体积和阴囊周长在 9 月最高，12 月次之，3 月最低（p<0.01）。尿道球腺长度在 3 月最大（p≤0.05），而前列腺长度在 9 月最大（p≤0.02）。精囊长度和宽度在 12 月最高，9 月次之，3 月最低（p≤0.02）。无论是总活力还是前向运动活力，3 月都最低（p<0.01），但 9 月和 12 月之间没有差异（p≥0.12）。12 月，雄鹿的正常精子比例最高，初级精子缺陷比例最低（p≤0.01）。总的来说，我们的研究结果表明，在北纬 40°的繁殖季节，白尾鹿雄鹿的繁殖和代谢特征存在变化。这里描述的生理变化将对从事白尾鹿雄鹿繁殖评估的兽医和研究人员有用。
