Lowell Kira J, Delgado Mikel M, Mederos Sabrina L, Bain Melissa J
Department of Medicine and Epidemiology, School of Veterinary Medicine, University of California at Davis, CA, 95616 USA.
Appl Anim Behav Sci. 2020 Nov;232. doi: 10.1016/j.applanim.2020.105130. Epub 2020 Sep 28.
It is unknown how premature maternal separation affects the responses of kittens to potentially stressful events. In the United States, thousands of kittens are orphaned each year due to death of the queen, neglect, or accidental separation by humans. Neonatal mammals emit distress calls and increase locomotion when socially isolated, suggesting that being separated from the nest is a stressful event. Increased vocalization and activity of isolated neonates may aid maternal retrieval or relocation of the nest. In the current study, we assessed the effects of early maternal separation on later vocalizations and activity of 49 kittens (28 orphaned, 21 mother-reared; 23 female, 26 male) from 11 litters (5 mothered, 6 orphaned) during an open field test when the kittens were one and three weeks of age. We conducted a total of 79 trials. Each kitten was placed individually in a 1-meter diameter pen away from the rest of the litter and/or mother for two minutes. The number of calls emitted and total activity (in seconds) were recorded for each kitten on every trial. We assessed the effects of age, sex, orphan status, and interactions between orphan status with sex and age on activity and vocalizations. Orphaned kittens were more active than mother-reared kittens at both times ((46) = 4.62, < 0.001), with an interaction between age and orphan status ((28) = -2.84, = 0.008). Orphaned kittens emitted more vocalizations at both times ( = 2.38, = 0.018), with an interaction between age and orphan status ( = -3.18, = 0.001). Orphaned kittens showed increased activity and vocalizations in response to a brief nest separation compared to mother-reared kittens. This effect was still present after over two weeks of maternal separation, suggesting that maternal separation may lead to long-term changes in stress responses. Future research should explore if such effects of maternal separation are present in older kittens or adult cats.
尚不清楚过早的母婴分离如何影响小猫对潜在应激事件的反应。在美国，每年有成千上万只小猫因母猫死亡、被忽视或人类意外分离而成为孤儿。新生哺乳动物在社交隔离时会发出求救叫声并增加活动量，这表明与巢穴分离是一个应激事件。孤立的新生儿增加发声和活动可能有助于母亲找回或重新安置巢穴。在本研究中，我们评估了早期母婴分离对49只小猫（28只孤儿猫、21只由母亲抚养；23只雌性、26只雄性）在旷场试验中的后期发声和活动的影响，这些小猫来自11窝（5窝由母亲抚养、6窝孤儿猫），年龄分别为1周和3周。我们总共进行了79次试验。每只小猫被单独放置在一个直径1米的围栏中，与其他同窝小猫和/或母亲分开两分钟。每次试验记录每只小猫发出的叫声数量和总活动量（以秒为单位）。我们评估了年龄、性别、孤儿状态以及孤儿状态与性别和年龄之间的相互作用对活动和发声的影响。在两个时间点，孤儿猫都比由母亲抚养的小猫更活跃（(46) = 4.62，< 0.001），年龄与孤儿状态之间存在相互作用（(28) = -2.84， = 0.008）。在两个时间点，孤儿猫发出的叫声都更多（ = 2.38， = 0.018），年龄与孤儿状态之间存在相互作用（ = -3.18， = 0.001）。与由母亲抚养的小猫相比，孤儿猫在短暂的巢穴分离后表现出活动和发声增加。在母婴分离超过两周后，这种效应仍然存在，这表明母婴分离可能导致应激反应的长期变化。未来的研究应该探索这种母婴分离的影响是否也存在于年龄较大的小猫或成年猫中。
