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Egg production systems have become subject to heightened levels of scrutiny. Multiple factors such as disease, skeletal and foot health, pest and parasite load, behavior, stress, affective states, nutrition, and genetics influence the level of welfare hens experience. Although the need to evaluate the influence of these factors on welfare is recognized, research is still in the early stages.
In this paper conventional cages are compared to furnished cages, non-cage systems, and outdoor systems. Specific attributes of each system are shown to affect welfare, and systems that have similar attributes are affected similarly.
Environments such as conventional cages, which limit movement, can lead to osteoporosis, but environments that have increased complexity, such as non-cage systems, expose hens to an increased incidence of bone fractures.
Less is understood about the stress that each system imposes on the hen, but it appears that each system has its unique challenges. Selective breeding for desired traits such as improved bone strength and decreased feather pecking and cannibalism may help to improve welfare.
It appears that no single housing system is ideal from a hen welfare perspective. Although environmental complexity increases behavioral opportunities, it also introduces difficulties in terms of disease and pest control.
One specific circumstance has not been taken into consideration in this paper: how to depopulate the hens in case of an outbreak situation. Emergency control is not an economic parameter to choose a specific production system, but comparing a production system with or without cages, it is clear that it is much easier to depopulate chickens in a system without cages. Without a proper technique to cull the animals in a animal welfare friendly way and to transport the carcasses out of the house mechanically, the chickens are killed and transported manually.
This is not only increasing the risks for humans to get infected, it also influences the risks that animals suffer unnecessary during depopulation. Handling animals during outbreak situations is mostly done by inexperienced responders who have little to no knowledge about animal welfare. Veterinary authorities in charge of the response activities have issues like effectiveness and efficiency to consider.
How to depopulate the chickens in an outbreak situation is an important welfare indicator and the producer of these systems need to be kept responsible for the technical solution.
Research Fellow Queensland University /
CEO AVT Europe AB
AVT Applied Veterinary Technologies Europe AB
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