Pedersen L J, Heiskanen T, Damm B I
Department of Animal Health and Welfare, Research Centre Foulum, Danish Institute of Agricultural Science, PO Box 50, Tjele DK-8830 Tjele, Denmark.
Anim Reprod Sci. 2003 Jan 15;75(1-2):39-53. doi: 10.1016/s0378-4320(02)00208-7.
The influence of social subordination on sexual motivation during oestrus was studied using 36 sows of which 24 treatment sows were housed in pairs and 12 control sows were housed individually in 12 and 6 m(2) pens, respectively. Video recordings were made from 07:00 h to 19:00 h during the first 2 days after grouping, which took place 3 days after weaning of the piglets. Based on the aggressive interactions between the pair-housed sows, their rank was determined. From day 4 after weaning, a test for sexual proceptive behaviour was carried out twice daily and back-pressure test was carried out four times daily in order to detect standing oestrus. When standing oestrus had occurred, transrectal ultrasonographical scans were also carried out in order to determine if ovulation took place. The proceptivity test took place in a T-maze with a 2 m x 10 m runway ending in two 1.5 m x 1.5 m goal boxes each adjacent to a stimulus compartment. One compartment contained an adult sexually experienced boar and the other was empty. Latency to and duration of time spent close to the boar and time spent presenting were recorded during the 10-min test period. On the first day that standing oestrus had been detected, a test for sexual receptivity was also carried out by introducing the sow to a mature boar in his home pen (9 m(2)). Sexual- and fear-related behaviour of sow and boar were recorded until mating was terminated or the sow had spent 5 min in the pen without mating being initiated. During oestrus the proceptivity test showed a significant increase (P < 0.05) in the time spent standing close to the boar and in presenting for single-housed sows and for pair-housed dominant sows, but not for subordinate sows. During oestrus subordinate sows spent significantly less time standing close to the boar than the dominant sows (P = 0.01) and the same tended to be the case for presenting (P = 0.07). In the receptivity test more subordinate sows than dominant sows fled (40% versus 0%, P = 0.001) and more subordinate sows than dominant sows squealed (58% versus 15%, P = 0.02) as a response to boar stimulation. In both tests, the single-housed sows differed neither from the dominant nor the subordinate sows. There was however no difference between the groups in the weaning to oestrous interval, duration of oestrus and number of piglet born. In addition, all the sows ovulated. The results indicate that social subordination can have significant consequences for sexual motivation in sows. Subordinate sows showed fear-related behaviour in response to boar stimulation even when they were in standing oestrus. Thus, both heat detection and mating may be impaired in subordinate sows. The results emphasise the importance to alleviate the social stress experienced by subordinates as well as the need for stock people to pay special attention to these animals when they are to be mated or inseminated.
利用36头母猪研究了社会从属地位对发情期性动机的影响，其中24头处理母猪成对饲养，12头对照母猪分别单独饲养在12平方米和6平方米的猪栏中。在仔猪断奶3天后分组，分组后的头2天，从07:00至19:00进行视频记录。根据成对饲养母猪之间的攻击互动确定其等级。从断奶后第4天起，每天进行两次性接受行为测试，每天进行四次背压测试以检测静立发情。出现静立发情时，还进行经直肠超声扫描以确定是否排卵。接受性测试在一个T型迷宫中进行，跑道长2米×10米，末端是两个1.5米×1.5米的目标箱，每个目标箱与一个刺激隔室相邻。一个隔室中有一头成年有性经验的公猪，另一个隔室为空。在10分钟的测试期内记录靠近公猪的潜伏期和时间、呈现的时间。在检测到静立发情的第一天，还通过将母猪引入其家栏（9平方米）中的成年公猪来进行性接受测试。记录母猪和公猪的性相关和恐惧相关行为，直到交配结束或母猪在栏中停留5分钟而未开始交配。发情期内，接受性测试显示，单栏饲养的母猪和成对饲养的优势母猪靠近公猪站立和呈现的时间显著增加（P < 0.05），但从属母猪没有。发情期内，从属母猪靠近公猪站立的时间显著少于优势母猪（P = 0.01），呈现方面也有类似趋势（P = 0.07）。在接受性测试中，作为对公猪刺激的反应，从属母猪比优势母猪更多地逃跑（40%对0%，P = 0.001），从属母猪比优势母猪更多地发出尖叫（58%对15%，P = 0.02）。在两项测试中，单栏饲养的母猪与优势母猪和从属母猪均无差异。然而，各组在断奶至发情间隔、发情持续时间和产仔数方面没有差异。此外，所有母猪均排卵。结果表明，社会从属地位可能对母猪的性动机产生重大影响。从属母猪即使在静立发情时对公猪刺激也表现出恐惧相关行为。因此，从属母猪的发情检测和交配可能都会受到损害。结果强调了减轻从属母猪所经历的社会压力以及饲养人员在对这些动物进行交配或授精时需要特别关注它们的重要性。
