Puy Sara, Giral Marta, García-Olmo Dolores C
Centre de Recerca Experimental Biomèdica Aplicada (CREBA), IRBLleida, 25138 Lleida, Spain.
Animal Research Facilities, Almirall SA, 08980 Barcelona, Spain.
Animals (Basel). 2024 Sep 24;14(19):2760. doi: 10.3390/ani14192760.
The goal of the present study was to evaluate the potential stress developed in farm hybrid pigs and miniature laboratory pigs briefly restrained in a sling, by measuring salivary cortisol levels. The study was performed in 20 healthy pigs grouped into three groups: group HYB-F: hybrid female pigs (n = 12), housed at the CREBA facility (Lleida, Spain); group MIN-F: Specipig miniature female pigs (n = 4), housed at the CREBA facility; group MIN-M: Specipig miniature male pigs (n = 4), housed at the Almirall facility (Barcelona, Spain). Upon arrival, the animals were enrolled in a social habituation and training program, which included habituation to a restraint sling. The sling was a stainless steel structure with a canvas hammock which had four openings for placing the animal's feet. The assessment of stress levels in the sling was carried out by measuring cortisol levels in saliva samples. Five saliva samples were collected from each animal over 4 days: Sample 1 (basal sample): taken after animals perceived the presence of the technicians in the pen; Sample 2: taken after animals saw the sling in the pen; Sample 3: taken when animals were in the sling; Sample 4: taken 1 min after the previous one; Sample 5: taken after animals were released back on the floor. In group HYB-F, five animals (5/12) showed strong resistance and could not be restrained in the sling on at least one day. All animals in the groups of miniature pigs could be restrained on all the days. Within each group, the manipulation phase did not affect salivary cortisol levels. Likewise, salivary cortisol levels did not change significantly across days in either group. In conclusion, salivary cortisol levels did not increase when pigs were lifted and briefly restrained in the sling, even though some of them (in particular, the hybrid pigs) showed apparent signs of stress. The lack of correlation between such apparent stress and salivary cortisol levels might be because the vocalizations and movements were not really signs of stress, but simply a way of releasing discomfort, learned in the process of socialization and habituation. In light of this unexpected conclusion, further studies are needed to collect other physiological and behavioral data to clarify what actually happens when pigs are restrained in a sling.
本研究的目的是通过测量唾液皮质醇水平，评估在吊床中短暂受限的农场杂交猪和小型实验猪所产生的潜在应激。该研究在20头健康猪中进行，这些猪被分为三组：HYB - F组：杂交母猪（n = 12），饲养在CREBA设施（西班牙莱里达）；MIN - F组：Specipig小型母猪（n = 4），饲养在CREBA设施；MIN - M组：Specipig小型公猪（n = 4），饲养在Almirall设施（西班牙巴塞罗那）。到达后，动物们参加了一个社交适应和训练项目，其中包括适应约束吊床。吊床是一个带有帆布吊床的不锈钢结构，有四个用于放置动物脚的开口。通过测量唾液样本中的皮质醇水平来评估吊床中的应激水平。在4天内从每只动物身上收集5份唾液样本：样本1（基础样本）：在动物感知到围栏中有技术人员后采集；样本2：在动物看到围栏中的吊床后采集；样本3：在动物处于吊床中时采集；样本4：在前一个样本采集1分钟后采集；样本5：在动物被放回地面后采集。在HYB - F组中，5只动物（5/12）表现出强烈抵抗，至少有一天无法被限制在吊床中。小型猪组中的所有动物在所有日子都能被限制住。在每组中，操作阶段不影响唾液皮质醇水平。同样，两组中唾液皮质醇水平在不同日子里均无显著变化。总之，当猪被吊起并在吊床中短暂限制时，唾液皮质醇水平并未升高，尽管其中一些猪（特别是杂交猪）表现出明显的应激迹象。这种明显的应激与唾液皮质醇水平之间缺乏相关性可能是因为发声和动作并非真正的应激迹象，而仅仅是在社交化和适应过程中学会的一种释放不适的方式。鉴于这一意外结论，需要进一步研究以收集其他生理和行为数据，以阐明当猪被限制在吊床中时实际发生了什么。
