## 2 Materials and Methods  
### Animals and Housing  
Data collection took place on an organic laying hen farm in Germany with 11,993 laying hens (Lohmann Brown Lite, Lohmann Tierzucht GmbH, Cuxhaven, Germany) kept after standards of the organic association \"Naturland\" [37]. The pullets were reared on an organic rearing farm in groups of 4100 pullets for 18 weeks. During the rearing period, the pullets were offered alfalfa hay bales and pecking blocks indoors and wood shavings and straw in the WG, which was accessible from the age of 7 weeks on. In August 2019, at the age of 129 days, the pullets were moved to the laying farm and were split into four groups (about 3000 hens each) housed under the same conditions in four separate units in the same henhouse. Each group had access to a WG and a free-range area. Each WG covered an area of 3.20 m \(\times\) 50 m (160 m\({}^{2}\)) and served as a transit zone from the inner henhouse to the free-range area. It was accessible during the light period of the day (at minimum from 9:00 to 20:00). The free-range area opened at 10:00 latest, and on ten of the evaluated days, it was closed due to bad weather to protect the animals' health condition. Two of the winter gardens (WGs) (3 and 4) faced the eastern direction, the other two (1 and 2) faced the western direction. The litter in the henhouse and the WGs consisted of straw pellets. In the free-range area, 4 m\({}^{2}\) of grassland per hen was available, with additional poplar avenues offering shade and protection against predators. Each WG had ten outlets of 2 m width towards the henhouse and ten outlets of 2-4 m width enabling the hens to enter the free-range area.  
Visits for data collection took place at week of life (LW) 19, 24, 28, 31, 35, 41, 54, 62, 70, and 77. Transport to slaughter took place at LW 78 in October 2020.  
The automatic enrichment device (PickPuck, Big Dutchman International GmbH, Vechta-Calveslage, Germany) used in this study was installed in WGs 1-4 of the henhouse (Figure 1a). The device consisted of a silo with a 6 m\({}^{3}\) capacity that was placed in the anteroom of WG 1. From the silo, a pipe system was installed below the roof of the WGs and went around the henhouse. Inside the pipeline, a chain with driving plates was used to transport material from the silo through the henhouse. In WG 2-4, at regular distances (approximately 7.2 m/3.6 m), a downpipe ended in a mechanism dosing the material to a pecking plate (PP) hung below. In WG 1 no such downpipes and pecking plates (PPs) were installed. The plate was rough-coated and swung free on a pendulum that influenced the material dosage onto the plate (Figure 1b). Harsh movement on the plate caused more material to be dosed, so that the hens could influence the dosage by pecking. During the observational periods, the downpipes were filled with grain, enabling the hens to access the material ad libitum from the enrichment device. The dosing mechanism could be adjusted in three steps. During the study, step two for pellets or bigger grains was used, as this enabled a precise dosing of the grains. The automatic enrichment device was installed following the manufacturers' recommendation of one downpipe with PP for 500 hens, approximately every 7.2 m, in WG 3 and 4 (single), resulting in six PPs in each WG. In WG 2, the number of downpipes with PPs was doubled (one for 250 hens, approx. every 3.6 m; double), resulting in 12 PPs in the WG. WG 1 was used as a control, and no downpipes and pecking plates were installed (control). In addition to the automatic enrichment device, pecking blocks and hay or straw and alfalfa hay bales hanging in nets were offered to the hens in all WGs. Inside the henhouse, each group had access to two boxes, offering material for dustbathing.