Jackson Alexandra, Quino Marcela, Gautam Anusha, Gilpin Melissa, Still Katie, Landers Denise, Baker-Cook Bethany
Department of Poultry Science, Auburn University, Office 302E, 260 Lem Morrison Dr., Auburn, Auburn, AL 36849, USA.
Department of Poultry Science, Auburn University, Office 302E, 260 Lem Morrison Dr., Auburn, Auburn, AL 36849, USA.
Poult Sci. 2025 Jan;104(1):104594. doi: 10.1016/j.psj.2024.104594. Epub 2024 Nov 26.
Fear tests are a common research method to assess the affective state of an animal. This study aimed to assess: 1) the impact of repeated exposure to fear tests on fear response and, 2) how the addition of movement to fear stimuli during a novel object test impacts bird fear response. Over two trials, a total of 3,600 Ross 308 birds (1800 birds/trial) were raised until 42 days of age. At 23d, 30d, and 37d, three fear tests were performed, novel object, human approach, and response to observer tests. The novel object test was split into three movement treatments, stationary, intermittent, and continuous. The response to observer test was performed before and after the other tests. Data from the human approach test was analyzed for age effect by ANOVA. Novel object data was analyzed as repeated measures ANOVA for the effect of movement. Differences in response to observer were analyzed using a paired T-test. Repeated exposure to fear test within the same day decreased the fear response, with response to observer results before fear testing (66%) differing from after (42%, P<0.01). The fear response also decreased with multiple consecutive exposures. Both latency to human approach and latency to novel object interaction were longest on 23d, then 30d, and shortest on 37d (P<0.01). For both the human approach and the novel object test, at all-time points, the number of birds interested in the human or object was higher on 37d than 23d (P<0.01). The addition of movement to the novel object test increased the fear response at 23 days but decreased the fear response at 37 days. Overall, the repeated exposure of birds to fear tests reduced the bird's fear response, both for the repeated exposure to different fear tests on a single day and the repeated exposure to one type of fear test over the length of a flock. This impact of repeated exposure is important to recognize when designing experiments that utilize fear tests.
恐惧测试是评估动物情感状态的一种常见研究方法。本研究旨在评估：1）重复进行恐惧测试对恐惧反应的影响，以及2）在新颖物体测试期间，向恐惧刺激中添加运动如何影响禽类的恐惧反应。在两项试验中，总共饲养了3600只罗斯308肉鸡（每次试验1800只）直至42日龄。在第23天、30天和37天，进行了三项恐惧测试，即新颖物体测试、人类接近测试和对观察者反应测试。新颖物体测试分为三种运动处理方式：静止、间歇和连续。对观察者反应测试在其他测试之前和之后进行。采用方差分析（ANOVA）分析人类接近测试数据的年龄效应。新颖物体测试数据作为重复测量方差分析，以分析运动的影响。使用配对t检验分析对观察者反应的差异。在同一天内重复进行恐惧测试会降低恐惧反应，恐惧测试前对观察者反应的结果（66%）与测试后（42%，P<0.01）不同。多次连续暴露后恐惧反应也会降低。人类接近的潜伏期和与新颖物体互动的潜伏期在第23天最长，其次是第30天，在第37天最短（P<0.01）。对于人类接近测试和新颖物体测试，在所有时间点，对人类或物体感兴趣的禽类数量在第37天高于第23天（P<0.01）。在新颖物体测试中添加运动会在第23天增加恐惧反应，但在第37天降低恐惧反应。总体而言，禽类重复进行恐惧测试会降低其恐惧反应，无论是在一天内重复进行不同的恐惧测试，还是在一群禽类的饲养期内重复进行一种类型的恐惧测试。在设计使用恐惧测试的实验时，认识到重复暴露的这种影响很重要。
