Effects of multiple daily litter applications on the dust bathing behaviour of laying hens kept in an enriched cage system

•The daily litter frequency had significant impact on dust bathing behaviour.•A litter application at least twice per day around mid-day can be recommended.•The law regulated minimum mat sizes are insufficient for dust bathing behaviour. Conventional ‘battery’ cages for laying hens without perches, nests and litter areas have been banned by law throughout the European Union since 1 January 2012. As an alternative solution, enriched cage systems were introduced. Our aim was to investigate how many applications of litter substrate per day are necessary to motivate laying hens to perform dust bathing behaviour, and to what extent the hens use these offered litter areas in a species-appropriate manner. Each of the two consecutive experiments was conducted for 12 months, during which 20 (experiment 1) and 40 (experiment 2) laying hens of the strains Lohmann Selected Leghorn (LSL) and Lohmann Brown Classic (LB) were housed in 10 units of the enriched cage system HÜK 125/80 (2 hens/unit [(experiment 1], 4 hens/unit [experiment 2], same strain per unit). In defined daily application frequencies from one to four times (11:00 a.m., 1:00 p.m., 3:00 p.m. and 5:00 p.m.) over the laying period, 50g conventional feed per application were applied as litter substrate onto each 925cm2 sized mat. The hens were recorded weekly by digital video systems. Results showed that the mean duration of dust bathing behaviour lasted 05:58min in experiment 1 and 04:59min in experiment 2. Litter application frequency had a significant effect on the dust bathing duration as well in experiment 1 (P