Rosenberger Katrina, Simmler Michael, Langbein Jan, Nawroth Christian, Keil Nina
Graduate School for Cellular and Biomedical Sciences, University of Bern, Bern, Switzerland.
Centre for Proper Housing of Ruminants and Pigs, Swiss Federal Food Safety and Veterinary Office, Agroscope, Ettenhausen, Switzerland.
PeerJ. 2022 Mar 29;10:e12893. doi: 10.7717/peerj.12893. eCollection 2022.
Current evidence suggests that frequent exposure to situations in which captive animals can solve cognitive tasks may have positive effects on stress responsiveness and thus on welfare. However, confounding factors often hamper the interpretation of study results. In this study, we used human-presented object-choice tests (in form of visual discrimination and reversal learning tests and a cognitive test battery), to assess the effect of long-term cognitive stimulation (44 sessions over 4-5 months) on behavioural and cardiac responses of female domestic goats in subsequent stress tests. To disentangle whether cognitive stimulation or the reward associated with the human-animal interaction required for testing was affecting the stress responsiveness, we conditioned three treatment groups: goats that were isolated for participation in human-presented cognitive tests and rewarded with food ('Cognitive', COG treatment), goats that were isolated as for the test exposure and rewarded with food by the experimenter without being administered the object-choice tests ('Positive', POS treatment), and goats that were isolated in the same test room but neither received a reward nor were administered the tests ('Isolation', ISO treatment). All treatment groups were subsequently tested in four stress tests: a novel arena test, a novel object test, a novel human test, and a weighing test in which goats had to enter and exit a scale cage. All treatment groups weretested at the same two research sites, each using two selection lines, namely dwarf goats, not selected for production traits, and dairy goats, selected for high productivity. Analysing the data with principal component analysis and linear mixed-effects models, we did not find evidence that cognitive testing (COG-POS contrast) reduces stress responsiveness of goats in subsequent stress tests. However, for dwarf goats but not for dairy goats, we found support for an effect of reward-associated human-animal interactions (POS-ISO contrast) at least for some stress test measures. Our results highlight the need to consider ontogenetic and genetic variation when assessing stress responsiveness and when interacting with goats.
目前的证据表明，让圈养动物频繁接触能够解决认知任务的情境，可能会对压力反应能力产生积极影响，进而对福利产生积极影响。然而，混杂因素常常妨碍对研究结果的解读。在本研究中，我们采用由人类呈现的物体选择测试（以视觉辨别和逆向学习测试以及一套认知测试组合的形式），来评估长期认知刺激（在4至5个月内进行44次测试）对雌性家养山羊在后续压力测试中的行为和心脏反应的影响。为了弄清楚是认知刺激还是测试所需的人与动物互动所带来的奖励影响了压力反应能力，我们设置了三个处理组：为参与由人类呈现的认知测试而被隔离并给予食物奖励的山羊（“认知组”，COG处理）、与测试暴露组一样被隔离但由实验者给予食物奖励而未进行物体选择测试的山羊（“积极组”，POS处理），以及被隔离在同一测试房间但既未获得奖励也未进行测试的山羊（“隔离组”，ISO处理）。随后，所有处理组都接受了四项压力测试：一个新环境测试、一个新物体测试、一个陌生人测试，以及一项称重测试，即山羊必须进出秤笼。所有处理组都在相同的两个研究地点进行测试，每个地点使用两个选育品系，即未选择生产性状的矮山羊和选择了高生产力的奶山羊。通过主成分分析和线性混合效应模型对数据进行分析，我们没有发现证据表明认知测试（COG - POS对比）会降低山羊在后续压力测试中的压力反应能力。然而，对于矮山羊而非奶山羊，我们发现至少对于某些压力测试指标，奖励相关的人与动物互动（POS - ISO对比）存在影响。我们的研究结果凸显了在评估压力反应能力以及与山羊互动时考虑个体发育和遗传变异的必要性。
