PhD Defence: Early-life strategies to improve welfare of laying hens on low-input and organic farms

Summary of dissertation

Improving laying hen welfare on small-scale and organic farms
In 2023, there were 387.4 million laying hens in the European Union (EU), 30 million of which were in the Netherlands. Only 22% of those in the Netherlands were considered free-range chickens. Free-range chickens have the opportunity to roam freely outdoors for at least part of the day and express essential behaviors, such as searching for food and dust- and sunbathing. When chickens are limited in their ability to behave in this way, they may develop higher levels of fear, stress, and damaging behavior such as feather pecking.

Early-life conditions, even before hatching, can determine how a chicken develops. Adapting these conditions to better match chicken needs may improve the chicken’s capacity to deal with later challenges. In other words, the chicken may be less fearful and develop less damaging behavior. Two strategies were tested in the experiments described in this dissertation, with the goal to adjust the early-life conditions to limit negative behavior (e.g. feather pecking) and stimulate positive behavior (e.g. searching for food). The first strategy comprised exposure to light during the artificial brooding of laying hen chicks (in contrast to brooding in complete darkness, which is currently default at commercial hatcheries); the second was to provide these chickens with live insect larvae in a food puzzle during the first 18 weeks of life. Although the effects were small, chickens that were exposed to light during brooding were slightly less fearful and chickens that had larvae access searched for food more often than the control groups.

Worldwide, the EU is frontrunner regarding laying hen welfare. This is shown, for example, in the relatively small percentage of chickens kept in cages. Nevertheless, there is still a lot of room for improvement, also on free-range farms. This requires a team effort from science, government, the poultry sector, and consumers.