Researchers find that, even in furnished cage systems that are thought to be “higher welfare,” layer hens' feather and bone conditions deteriorate significantly.

There are many ways of trying to improve the welfare of egg-laying hens: some farmers offer bigger cages, some farmers remove cages altogether, and still others, on a much smaller scale, actually allow hens to have outdoor access. This is not to say that any of these farming systems is “humane.” Still, when it comes to improving welfare, these are some common systems designed to do so.

In this study, researchers wanted to assess the lives layer hens kept in small furnished cages, to evaluate welfare implications of such a housing system. Keel bone damage (KBD), foot injuries and damage to the plumage and skin are likely to be painful to the birds and negatively influence the welfare of layer hens, so they concentrated on those risk factors. They visited 13 flocks at three intervals (32, 62 and 77 weeks), and during each visit, 100 hens were examined for various wounds.

When compared to industrial cage-free systems, hens kept in cages typically have lower risks of crashing due to flying into other birds or housing equipment caused by the low degree of environmental complexity and the limited space available for moving around. The researchers warn that although this may be beneficial in terms of avoiding KBD, restriction of movement causes a higher risk of developing bone loss resulting from having too little mechanical stress on the bones. Such conditions can lead to weaker bones, and, therefore, caged hens are also at risk of experiencing KBD, but as a result of restricted movement. It is commonly hypothesised that keel bone deviations are caused from long-term pressure on the weakened keel during roosting.

Hens housed in cage systems are kept on wire mesh, hence their feet are not exposed to moist litter with high amounts of ammonia. However, wire mesh in itself may cause foot injuries. For example,

toes and nails may become trapped and ripped off. Furthermore, caged hens often resort to feather pecking as a redirected foraging behaviour driven by a lack of foraging material.

Small Furnished Cages In Denmark

Furnished cages are now mandatory during the laying period across Europe. All farms that participated in the study had furnished cage systems allowing 8-10 hens per cage (compared to the maximum 10 allowed according to the Danish legislation). All cages had integrated perches, a scratching area, a nest available, and provided a minimum net area of 750 cm2 per hen (for comparison, an A4 size paper is 624 cm2). Due to the voluntary decision by the Danish Egg Association to omit beak trimming of caged layers back in 2013, all hens in this study had intact beaks. To give a sense of the scale of these “higher welfare” farms, each shed had between 5 and 18 double-sided rows of cages arranged in three or six tiers. The average number of birds per shed ranged from 18,000 to 90,528.

The study found that plumage and keel bone conditions deteriorated with age. Specifically, at 77 weeks of age, 16% of the birds had poor plumage and 43% of the birds had KBD. By contrast, foot pad lesions were most prevalent at 32 weeks of age, suggesting that the feet of young hens are too soft to live on wire mesh injury-free. The researchers recommend that prevention of damage to the keel bone, plumage and foot pads should therefore be considered in order to further improve welfare of layer hens housed in small furnished cages.

The ongoing collaboration between animal scientists and commercial farms gives optimism that both parties are interested in ensuring high animal welfare. Animal advocates may be pleased to learn about specific recommendations issued for improving the way we house layer hens in cages, and may also be frustrated in the lack of improvement that these new cages have made. These findings can be used as evidence when pressing for further improvements, by way of showing how little difference some existing improvements have made.