Ungerfeld Rodolfo, Orihuela Agustín, Pérez-Clariget Raquel
Departamento de Fisiología, Facultad de Veterinaria, Lasplaces 1620, Montevideo, 11600, Uruguay.
Facultad de Ciencias Agropecuarias, Universidad Autónoma del Estado de Morelos, Av. Universidad 1001, Colonia Chamilpa, Cuernavaca, Morelos, 62210, Mexico.
Theriogenology. 2019 Apr 15;129:99-102. doi: 10.1016/j.theriogenology.2019.02.033. Epub 2019 Feb 25.
Sexual performance of rams does not improve after observing hetero-sexual behavior of other rams, as happens in bucks and bulls. This lack of effect might be masked by the positive and negative effects that sexual stimulation could have on dominant or subordinate rams, given that important differences have been found within both categories. Thus, the objective of the present experiment was to determine if rams' sexual behavior is modified differently in dominant (DOM) and subordinated (SUB) rams after observing the sexual behavior of each other. The dominance relationship of nine dyads of Corriedale rams was determined using a food competition test. Next, each ram was tested in two different situations; a control test (CT), and a test in which the other ram was joined with two estrous ewes in the contiguous pen (visual sexual stimulation test; VSST). Estrous ewes were placed in one pen, and each ram was located first 20 min in the contiguous pen. Then, the ram was moved into the pen with the estrous ewes, staying there for other 20 min. During the CT the ewes remained alone the first 20 min. During the VSST the other ram of the dyad was in the pen with the ewes, but it was taken out before introducing the tested ram. There were no differences in the frequency of any behavior during the 20 first min between DOM or SUB rams. The DOM rams did not modify any behavior according to the type of test. On the other hand, SUB rams increased the number of ejaculations and the ejaculation efficiency (P = 0.04 and 0.03, respectively) when tested after viewing the DOM rams, and tended (P = 0.058) to achieve their 1st ejaculation earlier in VSST test. It was concluded that while visual pre-stimulation of a SUB ram courting and mating estrous ewes had no effect on DOM rams' sexual behavior, the observation of a DOM ram, enhanced mating behavior of SUB rams. This expands the concept that DOM and SUB rams respond with different strategies to visual stimulation.
与雄鹿和公牛不同，公羊在观察到其他公羊的异性性行为后，其性行为表现并不会得到改善。鉴于在这两类公羊中都发现了重要差异，性刺激对公羊的正负效应可能会掩盖这种缺乏效果的情况。因此，本实验的目的是确定在观察彼此的性行为后，优势（DOM）公羊和从属（SUB）公羊的性行为是否会有不同的改变。使用食物竞争测试确定了9对科里代尔公羊的优势关系。接下来，每只公羊在两种不同的情况下进行测试：对照测试（CT），以及将另一只公羊与两只发情母羊放在相邻围栏中的测试（视觉性刺激测试；VSST）。发情母羊被放在一个围栏中，每只公羊首先在相邻围栏中放置20分钟。然后，公羊被转移到有发情母羊的围栏中，再在那里停留20分钟。在对照测试中，母羊在前20分钟单独待着。在视觉性刺激测试中，二元组中的另一只公羊与母羊在围栏中，但在引入受试公羊之前将其带出。在最初的20分钟内，优势公羊或从属公羊的任何行为频率都没有差异。优势公羊不会根据测试类型改变任何行为。另一方面，从属公羊在观看优势公羊后进行测试时，射精次数和射精效率增加（分别为P = 0.04和0.03），并且在视觉性刺激测试中倾向于（P = 0.058）更早地实现第一次射精。得出的结论是，虽然从属公羊求偶和与发情母羊交配的视觉预刺激对优势公羊的性行为没有影响，但观察优势公羊会增强从属公羊的交配行为。这扩展了优势公羊和从属公羊对视觉刺激以不同策略做出反应的概念。
