Influence of different small-group-systems on production traits, egg quality and bone breaking strength of laying hens. 1st communication: Production traits and egg quality

The objective of the present investigation was to analyse the effect of furnished cages and two different small-group-systems on the production traits and egg quality traits of laying hens. Each housing system contained two different group sizes. In the first trial (July 2002 – July 2003) a white layer line (Lohmann Selected Leghorn: LSL) and a brown layer line (Lohmann Brown: LB) were equally distributed among the different housing systems, but not mixed within a cage. In the second trial (September 2003 – June 2004) only white layers (LSL) were analysed. Throughout the whole laying period the hens had identical feeding and management. Every four weeks a sample of 180 eggs was examined for egg quality traits. The investigations started in the first trial in the seventh laying month and in the second trial in the second laying month. A total number of 2420 eggs was included in the examination. The LB-layer line showed, compared to the LSL-layer line, higher values for the traits egg production per average hen housed, egg mass per hen housed and per average hen housed, egg weight, yolk colour and proportion of meat spots. Furthermore, the LB-layer line showed a lower proportion of dirty eggs. However, the proportion of cracked eggs was lower for the LSL-layer line, while the values for the traits Haugh Units and shell density were higher for the LSL-layer line. In the system Aviplus both layer lines showed a higher egg production per average hen housed than in the Eurovent-systems, whereas the traits shell thickness, shell density and shell breaking strength were lowest in the system Aviplus. Furthermore, the egg production in the groups with 20 hens in the systems Aviplus and Eurovent 625A was higher than in the groups with 10 hens. In the first trial the proportion of dirty eggs was for both layer lines lowest in the system Aviplus. Besides that the proportion of dirty eggs was higher in the respective small groups of the two Euroventsystems than in the respective larger groups. For the LSL-layer line the highest proportion of cracked eggs was registered in the system Eurovent 625a, while for the LB-layer line the proportion of cracked eggs was highest in the system Aviplus. In the groups with 60 hens the proportion of cracked eggs was higher than in the groups with 40 hens of the system Eurovent 625a. Besides that eggs from the system Eurovent 625a were heavier than in the two other systems and the LB-layer line produced eggs with the highest amount of meat spots in the system Eurovent 625a. Thus, the present investigation showed that in furnished cages and small-groupsystems high laying performances and good egg quality traits could be achieved, whereas the respective group size seemed to be less important. Furthermore, it seemed possible to improve eggshell quality in the small-group-systems compared to the furnished cages.

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