摘要 : <abstract_text><p>1. Bone stability of five purebred layer lines differing in performance efficiency and phylogenetic origin was investigated within two housing systems.</p><p>2. Hens were kept in single ca... 展开 <abstract_text><p>1. Bone stability of five purebred layer lines differing in performance efficiency and phylogenetic origin was investigated within two housing systems.</p><p>2. Hens were kept in single cages or floor pens until the end of the 74 th week of age. At that time, they were sacrificed and examined for humeral and tibial traits.</p><p>3. Within a phylogenetic group, hens of the low performing lines had higher bone breaking strengths compared to their high performing counterparts. The bone mineral density of the tibia was significantly lower in the high performing brown egg layers than in the low performing ones.</p><p>4. Within and among layer lines, birds in floor housing had significantly higher tibia and humerus breaking strengths as well as higher bone weights than caged hens.</p><p>5. The differences between the high and low performing layer lines suggest a negative association between egg laying performance and bone stability in laying hens, irrespective of their phylogenetic origin. Moreover, the results confirm the already known effect of the housing system on bone strength.</p></abstract_text> 收起