Department of Biometry, Epidemiology and Information Processing, WHO Collaborating Center for Research and Training for Health at the Human-Animal-Environment Interface, University for Veterinary Medicine Hanover, Foundation, Buenteweg 2, D-30559 Hannover, Germany.
Department of Epidemiology, French Agency for Food, Environmental, and Occupational Health Safety (ANSES), Zoopole, Ploufragan, France.
Poult Sci. 2018 Feb 1;97(2):358-367. doi: 10.3382/ps/pex321.
An important indicator of the health and behavior of laying hens is their plumage condition. Various scoring systems are used, and various risk factors for feather damage have been described. Often, a summarized score of different body parts is used to describe the overall condition of the plumage of a bird. However, it has not yet been assessed whether such a whole body plumage score is a suitable outcome variable when analyzing the risk factors for plumage deterioration. Data collected within a German project on farms keeping laying hens in aviaries were analyzed to investigate whether and the extent to which information is lost when summarizing the scores of the separate body parts. Two models were fitted using multiblock redundancy analysis, in which the first model included the whole body score as one outcome variable, while the second model included the scores of the individual body parts as multiple outcome variables. Although basically similar influences could be discovered with both models, the investigation of the individual body parts allowed for consideration of the influences on each body part separately and for the identification of additional influences. Furthermore, ambivalent influences (a factor differently associated with 2 different outcomes) could be detected with this approach, and possible dilutive effects were avoided. We conclude that influences might be underestimated or even missed when modeling their explanatory power for an overall score only. Therefore, multivariate methods that allow for the consideration of individual body parts are an interesting option when investigating influences on plumage condition.
蛋鸡的羽毛状况是其健康和行为的一个重要指标。目前使用了各种评分系统，并描述了各种导致羽毛损伤的风险因素。通常，使用不同身体部位的综合评分来描述鸟类羽毛的整体状况。然而，当分析导致羽毛恶化的风险因素时，这种全身羽毛评分是否适合作为结果变量，尚未得到评估。对在笼养环境中饲养蛋鸡的德国项目中收集的数据进行了分析，以研究在对各个身体部位的评分进行汇总时是否以及在何种程度上会丢失信息。使用多块冗余分析拟合了两个模型，其中第一个模型将全身评分作为一个结果变量，而第二个模型将各个身体部位的评分作为多个结果变量。尽管这两个模型基本上可以发现类似的影响，但对各个身体部位的研究可以分别考虑每个身体部位的影响，并确定其他影响因素。此外，这种方法可以检测到矛盾的影响（一个因素与两个不同的结果相关联），并避免可能的稀释效应。我们得出结论，当仅对整体评分进行建模以评估其解释能力时，可能会低估甚至错过影响因素。因此，当研究羽毛状况的影响因素时，允许考虑各个身体部位的多元方法是一个有趣的选择。
