Analysis of genotype-environment interactions between layer lines and hen housing systems for performance traits, egg quality and bone breaking strength -: 3rd communication:: Bone breaking strength

Tibia and humerus breaking strength of a white layer line (Lohmann Selected Leghorn, LSL) and of a brown layer line (Lohmann Tradition, LT) was examined between three hen housing systems, battery cages, aviary and intensive free range system. Bone strength was investigated at the end of the laying period of the hens aged about 13 months. The highest differences between the LT and the LSL-layer lines were obvious in bone breaking strength for hens kept in battery cages. For both layer lines the bone breaking strength was consistently higher for hens kept in the aviary or in the intensive free range system as compared to battery cages. A striking feature of this study was the excessive increase of the bone breaking strength of the LSL-hens in the alternative housing systems compared to battery cages. The LSL-hens reached the highest tibia breaking strength in the intensive free range system and the LT-hens the highest humerus breaking strength in the aviary.