Laying hens are kept in a variety of housing systems, varying from small sized enriched cages to large non-cage units. Although the majority of hens in Europe are kept in cages, especially in Northern Europe the number of non-cages systems is increasing. Non-cage systems comprise simple single tier barn units, but also multitier aviary systems.
With regards to risk for injuries and DOAs (birds dead on arrival) the housing system does have an influence:
- First the housing system can have an influence on the health of the birds and thus on the fitness for travel. In non-cage systems birds are more likely to come into contact with their own manure, which means a risk for worms, coccidiosis and infectious diseases. These diseases form a risk for bird health and often cause mortality. Weeks et al (2012a) found higher mortality in non-cage systems compared to colony cages. They also found an increased risk of DOA in flocks with poor feather cover, poor health, lower body weight and higher cumulative mortality.
- Second the housing system as such can have an influence on the ease of catching the birds. Furnished cages have cage doors and the depth of the cage makes it difficult to catch the birds. Having people catching birds on both sides of the system or people driving the birds to the catchers may help. Another difficulty of these systems is the number of tiers and accessibility of the cages. Finally cage houses often are large, increasing the distance from cage to truck. If catchers have to walk the full length of the house many times, this will influence their handling of birds and may result in extra injuries. Non-cage systems require catching birds in the dark. At night, the majority of birds are on the top floor, which requires catchers to climb onto the system, catch birds and hand them over to helpers down in the litter area. As in cages bids have to be drawn from behind perches, feed troughs and out of nest boxes, but under dark circumstances this may lead to more damage to the birds. Also catchers often have to walk through the litter, which is a very uneven surface and may cause birds to bounce into furniture, possibly leading to injured birds. Large henhouses often are subdivided into sections by means of wire. Walking from one section to the other is possible, but doors have to be opened and as catchers are passing these doors in the dark, there is an additional risk for birds bouncing into door posts.
Aisles and doorways
The efficiency of catching and crating birds is also influenced by the condition of the aisles in housing systems. Wide aisles with clean concrete floors allow the use of carts or small motorized equipment to bring crates into the house, thus reducing the distance birds need to be carried.
Other factors may also influence the possibilities to bring crates into the house, such as the size of doorways and obstacles preventing the use of carts.
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