Campbell Dana L M, Taylor Peta S, Hernandez Carlos E, Stewart Mairi, Belson Sue, Lee Caroline
Agriculture and Food, Commonwealth Scientific and Industrial Research Organisation (CSIRO), Armidale, NSW, Australia.
School of Environmental and Rural Science, University of New England, Armidale, NSW, Australia.
PeerJ. 2019 Jul 10;7:e7303. doi: 10.7717/peerj.7303. eCollection 2019.
Fear is a response to a known threat, anxiety is a response to a perceived threat. Both of these affective states can be detrimental to animal welfare in modern housing environments. In comparison to the well-validated tests for assessing fear in laying hens, tests for measuring anxiety are less developed. Perception of a threat can result in an attention bias that may indicate anxious affective states in individual hens following playback of an alarm call. In Experiment 1, an attention bias test was applied to hens that differed in their range access to show that hens that never ranged were more vigilant (stretching of the neck and looking around: < 0.001) and slower to feed following the second alarm call playback ( = 0.01) compared with hens that ranged daily. All hens showed a reduction in comb temperature following the first alarm call ( < 0.001). In Experiment 2, an open field test was used to determine an effective dose of 2 mg/kg for the anxiogenic drug -Chlorophenylpiperazine (-CPP) in adult laying hens. Hens dosed with 2 mg/kg showed reduced locomotion compared with a saline solution ( < 0.05). In Experiment 3, 2 mg/kg -CPP or saline was administered to adult hens previously habituated to the open field arena to pharmacologically validate an attention bias test as a measure of anxiety. Hens dosed with -CPP were slower to feed ( = 0.02) and faster to vocalize following a second alarm call playback ( = 0.03) but these hens did not exhibit the same vigilance behavior as documented in Experiment 1. The -CPP hens also spent more time stepping and vocalizing (both < 0.001) than the saline hens. An attention bias test could be used to assess anxiety. However, behavioral responses of hens may vary depending on their age or test environment familiarity, thus further refinement of the test is required. In these tests, 2 mg/kg of -CPP resulted in motionless behavior when the environment was novel, but more movement and vocalizing when the environment was familiar. The extreme behavioral phenotypes exhibited by individually-tested birds may both be indicators of negative states.
恐惧是对已知威胁的反应，焦虑是对感知到的威胁的反应。在现代饲养环境中，这两种情感状态都可能对动物福利有害。与评估蛋鸡恐惧的经过充分验证的测试相比，测量焦虑的测试发展得较少。对威胁的感知会导致注意力偏差，这可能表明在播放警报声后个体母鸡处于焦虑的情感状态。在实验1中，对活动范围不同的母鸡进行了注意力偏差测试，结果表明，与每天都有活动范围的母鸡相比，从未有过活动范围的母鸡更加警觉（伸脖子和环顾四周：<0.001），在第二次播放警报声后进食速度更慢（=0.01）。所有母鸡在第一次播放警报声后鸡冠温度都有所下降（<0.001）。在实验2中，使用旷场试验来确定成年蛋鸡中致焦虑药物——氯苯哌嗪（-CPP）的有效剂量为2mg/kg。与注射生理盐水的母鸡相比，注射2mg/kg -CPP的母鸡活动减少（<0.05）。在实验3中，对先前已适应旷场试验场地的成年母鸡注射2mg/kg -CPP或生理盐水，以从药理学角度验证注意力偏差测试作为焦虑测量方法的有效性。注射-CPP的母鸡在第二次播放警报声后进食速度更慢（=0.02），发声更快（=0.03），但这些母鸡没有表现出与实验1中记录的相同的警觉行为。注射-CPP的母鸡比注射生理盐水的母鸡花费更多时间走动和发声（两者均<0.001）。注意力偏差测试可用于评估焦虑。然而，母鸡的行为反应可能因其年龄或对测试环境的熟悉程度而异，因此需要进一步完善该测试。在这些测试中，2mg/kg的-CPP在环境新颖时会导致静止行为，但在环境熟悉时会导致更多的活动和发声。单独测试的鸟类表现出的极端行为表型都可能是负面状态的指标。
