Abstract：
1. Keel bone damage, such as deformations and fractures, is a severe problem regarding animal welfare in layers. To identify risk factors under commercial conditions, 33 layer flocks (22 barn, 11 free range) with white (n = 18), brown (n = 11) and mixed (n = 4) genotypes were examined.2. Keel bone status was frequently scored by palpation throughout the laying period. Data on housing and management conditions were collected. Multiple regression and Generalized Estimating Equations procedure were used for analysis.3. At 65-74 weeks of age, the prevalence of keel bone damage ranged between 26% and 74%. White genotypes and those kept in multi-tier systems developed significantly (p < 0.05) more keel bone damage than brown genotypes or those kept in single-tier systems. Wing feather condition was associated with keel bone damage (p < 0.05), while other investigated variables regarding health, housing and management were not associated.4. In conclusion, housing and management should be adapted to meet the birds\' specific needs in multi-tier systems, which may vary for brown and white genotypes. Whether those differences result from genotype associated predispositions or other individual traits remains to be determined.
摘要：
1.龙骨损伤,如变形和骨折，是一个关于分层动物福利的严重问题。为了识别商业条件下的风险因素，33层群(22个谷仓，11自由范围)带白色(n=18)，检测了棕色（n=11）和混合（n=4）基因型。在整个产蛋期间，触诊经常对龙骨状态进行评分。收集了有关住房和管理条件的数据。多元回归和广义估计方程程序用于分析。65-74周龄，龙骨损伤的患病率在26%至74%之间。白色基因型和保留在多层系统中的那些比棕色基因型或保留在单层系统中的那些明显（p<0.05）更多的龙骨损伤。翼羽状况与龙骨骨损伤有关(p<0.05),而其他关于健康的变量调查，住房和管理没有关联。总之,住房和管理应适应多层系统中鸟类的特定需求，棕色和白色基因型可能有所不同。这些差异是否由基因型相关的易感性或其他个体性状引起仍有待确定。
