## 4 Discussion
The average number of hens per PP was 3.37, while other results showed that less than three hens use one alfalfa hay bale simultaneously [34]. During the peak of lay, this number increased to 5.11 hens/PP simultaneously, indicating increased pecking needs in this phase, which can also be indicated by the occurrence of severe feather pecking increases over the laying period [7; 46]. Hence, the findings imply that the automatic enrichment device may occupy more animals simultaneously than commonly used materials. Since only the use of one PP was evaluated in each WG, it is possible that the other PPs were occupied differently, depending on their location within the WG. A higher offer of PPs (in WG 2) however, did not reduce the number of animals using one PP simultaneously, thus showing that with more enrichment, a greater number of hens can be motivated to use these materials. A limitation of the enrichment device was its dosing mechanism. The dosing step used in this study was supposed to dose grain or pellets, but not every peck at the PPs resulted in grains falling out. Sometimes several harsh pecks were needed to cause the dosing of the material, which could result in hens losing interest in the device if there was no easily obtained reward. The attractiveness of the enrichment device could possibly be increased by using a smoother dosing mechanism for the grains. On the one hand, the PPs could increase hens' interest in it if every peck resulted in grains and would result in higher animal densities around the PPs. However, on the other hand, putting effort into the feed intake can be seen as environmental enrichment and could improve animal welfare [47]. Too many grains offered at the enrichment device could lead to a supplanting of the base feeding in the henhouse. The amount of grain offered in this study did not affect the hens' weights. Other parameters, such as daily feed intake, could not be recorded separately for the different groups, but the average of all groups was within the breeder's recommendations. Enrichment materials, which promote foraging behavior, tend to suit animals' needs best, resulting in less feather pecking behavior [29]. The enrichment device studied attracted hens and functioned when pecks were delivered on its rough pecking plate. Moreover, the device may also fulfill the entirety of foraging behavior since scratching for grain that fell from the plate and searching for spilled grain is also encouraged. Observations of foraging behavior via video recordings could confirm this assumption in further investigations. In this study, sometimes additional enrichment material, such as hay or straw bales in nets and pecking blocks, was offered in the WGs. This increased the number of animals per m\({}^{2}\) in a statistically significant way. Hence, enrichment material was offered in all WGs simultaneously, and no effect on the usage behavior of the PPs could be observed; its influence on the experiment was negligible. Other influencing factors, such as the status of the outlets towards the free-range area (opened/closed) and the compass direction of the WGs, did not show significant impact on the number of animals per m\({}^{2}\) in early statistical models. Therefore, these influencing factors on the number of animals in the WGs were excluded from the final analysis. Further research should focus on the actual influence of the device on the animals' WG use without the effect of the WG position. Observations of a potential difference in lengths of stay in differently enriched groups and hens' behavior could give insight into the direct use of enrichment materials. In combination with plumage scoring, such research could also provide insights on the influence of the enrichment device on feather pecking and cannibalism. In conclusion, the automatic enrichment device with PPs encouraged the use of WGs for laying hens, especially during the first weeks of egg production.