Alexander B M, Stellflug J N, Rose J D, Fitzgerald J A, Moss G E
Reproductive Biology Program, University of Wyoming, Laramie 82071, USA.
J Anim Sci. 1999 Jul;77(7):1869-74. doi: 10.2527/1999.7771869x.
High-performing, low-performing, and male-oriented rams were used to investigate behavior and neuroendocrine correlates of sexual interest and discrimination. Treatment consisted of visual and olfactory contact with stimulus animals through a woven wire fence, which inhibited copulation (either ewes in estrus or other rams), for 4 h on each of three consecutive days. Before exposure to stimulus animals on d 1 and during the final 1 h of exposure on d 2, blood samples were collected every 15 min for 1 h to determine concentrations of LH and testosterone. During exposure to stimulus animals, rams were continuously observed and investigatory behaviors were recorded. There was no day effect for any behavior. Groups of rams differed (P < .05) in amounts of behaviors exhibited, but behaviors were not influenced by sex of stimulus animals. High-performing rams exhibited more (P < .05) investigatory behaviors toward stimulus animals than low-performing or male-oriented rams. Plasma concentrations of LH increased (P < .05) in high-performing rams following exposure to estrous ewes, but not following exposure to rams. In low-performing and male-orientated rams, concentrations of LH were unchanged regardless of sex of the stimulus animal. Change in plasma concentrations of testosterone from pre- to posttreatment did not differ between high-performing, low-performing, and male-oriented rams. However, low-performing rams exhibited an increase (P < .05) in plasma concentrations of testosterone following exposure to rams. In conclusion, high-performing rams exhibit a high degree of investigatory behaviors toward estrous ewes and other rams. High-performing rams seem to discriminate sex of stimulus animals and exhibit a neuroendocrine response (i.e., increased plasma LH) only when exposed to ewes in estrus. The sensory signals provided by estrous females are either not detected by low-performing or male-oriented rams or are not sufficiently provocative to elicit further investigation by these rams.
使用表现优秀、表现不佳和雄性偏好的公羊来研究性兴趣和辨别能力的行为及神经内分泌相关性。处理方式为通过编织铁丝网围栏与刺激动物进行视觉和嗅觉接触，这种方式会抑制交配（发情母羊或其他公羊），连续三天每天接触4小时。在第1天接触刺激动物之前以及第2天接触的最后1小时内，每隔15分钟采集一次血样，共采集1小时，以测定促黄体生成素（LH）和睾酮的浓度。在接触刺激动物期间，持续观察公羊并记录探究行为。任何行为均无日效应。不同组的公羊在表现出的行为数量上存在差异（P <.05），但行为不受刺激动物性别的影响。表现优秀的公羊对刺激动物表现出的探究行为比表现不佳或雄性偏好的公羊更多（P <.05）。接触发情母羊后，表现优秀的公羊血浆中LH浓度升高（P <.05），但接触公羊后未升高。在表现不佳和雄性偏好的公羊中，无论刺激动物的性别如何，LH浓度均无变化。表现优秀、表现不佳和雄性偏好的公羊在处理前后血浆睾酮浓度的变化没有差异。然而，表现不佳的公羊在接触公羊后血浆睾酮浓度升高（P <.05）。总之，表现优秀的公羊对发情母羊和其他公羊表现出高度探究行为。表现优秀的公羊似乎能够辨别刺激动物的性别，并且仅在接触发情母羊时才表现出神经内分泌反应（即血浆LH升高）。表现不佳或雄性偏好的公羊要么未检测到发情母羊提供的感觉信号，要么这些信号不足以激发它们进行进一步探究。
