Fat status in Lohmann Silver and Lohmann Tradition laying hens kept in modified small group housing systems, small group housing systems, furnished cages and an aviary system

The influence of different housing systems on adiposis of liver, abdomen and heart was evaluated in 670 Lohmann Silver (LS) and 240 Lohmann Tradition (LT) laying hens during two trials. Examinations took place in the 3(rd), 6(th), 9(th) and 12(th) laying month. In addition, serum concentration of triglycerides (TRI) was analysed. Housing systems included in this study were a furnished cage system (Aviplus (AP)), a small group housing system (Eurovent 625a-EU (EV)), with perches on the same (first trial) and on different levels (second trial, MEV), and an aviary system (Voliere Natura (AV)). In both trials, a significantly lower fat status of abdomen and liver could be observed in hens housed in AV. Consistently in both trials, body weight and housing system had the largest influence on fat status of liver, abdomen and heart. Scores of fat status of liver and abdomen in EV and MEV were in between of those observed in AV and AP, while heart fat status did not differ among housing systems. With an increasing macroscopic fat status of the liver, liver weight and TRI concentration significantly increased. Different perch positions in MEV did not have a significant influence on fat status in layers.