Jung Lisa, Kulig Boris, Louton Helen, Knierim Ute
Farm Animal Behaviour and Husbandry Section, University of Kassel, Kassel, Germany.
Agricultural and Biosystems Engineering, University of Kassel, Kassel, Germany.
PLoS One. 2024 Dec 2;19(12):e0309137. doi: 10.1371/journal.pone.0309137. eCollection 2024.
Two major welfare problems in laying hen farming are keel bone damage (KBD) and cannibalism. Their assessment is time-consuming, needs well-trained assessors, and prevalence estimates are often imprecise due to small sample sizes. Here, the bottleneck slaughterhouse comes into focus where large numbers of animals can be inspected. However, this is only an option if the prevalences recorded at the slaughterhouse reasonably agree with on-farm assessments. The aim of this study was to compare the prevalence of KBD and skin injuries in 20 commercial laying hen flocks (i) before depopulation on-farm (ii) after transport and lairage time at arrival at the slaughterhouse, and (iii) at the slaughter line. Bland-Altman plots and equivalence tests were conducted. In addition, the consistency of welfare evaluations of the results according to a traffic light scheme was investigated. Cloacal injuries could not technically be recorded on the slaughter line. With an arbitrary precision of ± 2% for dorsal skin injuries and ± 5% for KBD, the results from farm and slaughter line did not reach equivalence. For dorsal skin injuries, the detected mean prevalence across all flocks examined increased numerically from the farm (15.1%) to the slaughter line (22.8%). In addition, the traffic light evaluations changed between farm and slaughter line in 80% of cases in different directions. Therefore, it cannot be recommended to derive evaluations of on-farm welfare from assessments of skin injuries at the slaughter line. In contrast, the mean detected prevalence of KBD across all flocks decreased consistently (r = 0.794) from the farm (56.0%) to the slaughter line (41.7%). It can be concluded that the assessment of KBD at the slaughter line consistently underestimates KBD prevalences compared to on-farm assessments, but this can be taken into account in the interpretation of the results. Slaughter line assessment of KBD may be a feasible option for monitoring severe welfare problems due to KBD in commercial practice.
蛋鸡养殖中的两个主要福利问题是龙骨损伤（KBD）和同类相残。对它们的评估耗时，需要训练有素的评估人员，而且由于样本量小，患病率估计往往不准确。在此，瓶颈屠宰场成为焦点，因为在那里可以检查大量动物。然而，只有当屠宰场记录的患病率与农场评估合理一致时，这才是一种选择。本研究的目的是比较20个商业蛋鸡群中（i）农场淘汰前、（ii）运输和在屠宰场到达后的休息时间后以及（iii）屠宰线上KBD和皮肤损伤的患病率。进行了Bland-Altman图和等效性检验。此外，还研究了根据交通信号灯方案对结果进行福利评估的一致性。在屠宰线上无法从技术上记录泄殖腔损伤。对于背部皮肤损伤，任意精度为±2%，对于KBD为±5%，农场和屠宰线的结果未达到等效性。对于背部皮肤损伤，在所有检查的鸡群中检测到的平均患病率从农场的（15.1%）到屠宰线的（22.8%）在数值上有所增加。此外，在80%的情况下，农场和屠宰线之间的交通信号灯评估朝着不同方向变化。因此，不建议根据屠宰线的皮肤损伤评估来推断农场福利评估。相比之下，所有鸡群中检测到的KBD平均患病率从农场的（56.0%）到屠宰线的（41.7%）持续下降（r = 0.794）。可以得出结论，与农场评估相比，屠宰线对KBD的评估始终低估了KBD患病率，但这可以在结果解释中予以考虑。在商业实践中，屠宰线对KBD的评估可能是监测因KBD导致的严重福利问题的可行选择。
