Ungerfeld R, Ramos M A, Bielli A
Departamento de Fisiología, Facultad de Veterinaria, Lasplaces 1550, Montevideo 11600, Uruguay.
Anim Reprod Sci. 2007 Aug;100(3-4):385-90. doi: 10.1016/j.anireprosci.2006.09.022. Epub 2006 Sep 20.
To characterize male-male sexual behavior during lamb development, to relate it with lamb body and testicular growth, and with sexual behavior toward estrual ewes, 40 Milchschaf male lambs, weaned at 45 days of age, were kept with ewes that were nursing younger lambs. Experimental lambs were weighed and scrotal circumference was measured every 2 weeks. Male-male sexual behavior was observed during 1-2 h every 2 weeks after birth until 7 months of age. Observations were recorded more intensively (3-4 h on five different days) for 2 weeks (5-6 months of age) as male-male sexual behavior increased during that period. Both mounting and mounted lambs were identified. An individual mounting index (MI) was calculated. To study male-female sexual behavior, lambs were individually located with two estrual ewes, and during 5 min the number of ano-genital sniffing, lateral approaches, mounts, and mounts with ejaculation were recorded. From those data, a libido index was also calculated. Male-male mounts (n=308) were observed. Courtship behavior was displayed in 25% of interactions; mounts were accepted in 72.1% of attempted mounts. Mounts without previous courtship were accepted more frequently than mounts with previous courtship (P=0.002). Lamb weight and scrotal circumference were not different according to MI groups. Lambs that mounted more times estrual ewes (first tertile) had greater (P=0.04) MI (0.61+/-0.10) than lambs with medium (0.27+/-0.09) and less (0.30+/-0.10) MI. The regression between MI and heterosexual libido index was r=0.33 (P<0.05). In summary, intensive male-male sexual activity during a short period of male lamb development was observed. There was a positive relationship between sexual behavior of male lambs towards other male lambs and towards estrual ewes.
为了描述雄性羔羊发育过程中的雄性间性行为，将其与羔羊身体和睾丸生长以及对发情母羊的性行为相关联，选取了40只45日龄断奶的米尔施夏夫雄性羔羊，与正在哺育较年幼羔羊的母羊饲养在一起。每2周对实验羔羊称重并测量阴囊周长。从出生到7月龄，每2周观察1 - 2小时的雄性间性行为。在5 - 6月龄期间，由于该阶段雄性间性行为增加，观察更为密集（在五个不同日期进行3 - 4小时观察），持续2周。确定了爬跨和被爬跨的羔羊，并计算了个体爬跨指数（MI）。为了研究雄性与雌性间的性行为，将羔羊分别与两只发情母羊放在一起，记录5分钟内肛门 - 生殖器嗅闻、侧向靠近、爬跨以及射精爬跨的次数。根据这些数据，还计算了性欲指数。观察到雄性间爬跨行为（n = 308次）。25%的互动中表现出求偶行为；72.1%的尝试爬跨被接受。无前戏的爬跨比有前戏的爬跨更常被接受（P = 0.002）。根据MI分组，羔羊体重和阴囊周长无差异。爬跨发情母羊次数较多（第一三分位数）的羔羊，其MI（0.61±0.10）显著高于MI中等（0.27±0.09）和较低（0.30±0.10）的羔羊（P = 0.04）。MI与异性性欲指数之间的回归系数r = 0.33（P < 0.05）。总之，观察到在雄性羔羊发育的短时期内有强烈的雄性间性活动。雄性羔羊对其他雄性羔羊的性行为与对发情母羊的性行为之间存在正相关。
