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Cage Housing "Do they like it in there?"
Cunningham and Mauldin reviewed the scientific literature on cage housing and beak trimming and the effects on the welfare and production of commercial egg layers.
Caged housing of layers is one of the most criticized practices in animal agriculture. Our society is uncomfortable with housing multiple birds in small cages. Some countries in Europe have moved away from cage housing or are providing more liberal space (600 cm2/hen). Almost all of the egg layer operations in Canada, like the rest of the world, continue to use multiple bird, high density cages (310 to 387 cm2/hen). New egg production complexes built in the US are all high density cage systems. Cage systems are used because they combine economic efficiency with high egg production levels.
Floor pens, aviaries and get away cages have all been compared to intensive cage systems. Under good management, one system has not been shown to be better than another in terms of welfare or production. There is a lack of evidence in the scientific literature indicating that caging in itself compromises the welfare of the birds. However, crowding and high density do have adverse effects on production and welfare of chickens regardless of what system of housing is being used. Obviously at some point adding one more bird to any housing system will compromise welfare.
As cage density increases, health and productivity of the birds decreases. A summary of 12 years of published research has shown that decreasing floor space from 387 cm2/hen to 310 cm2/hen reduces egg production by 16.6 eggs per hen housed, feed consumption by 1.9 g/hen/day and increases mortality by 4.8%. In this case, welfare and overall productivity decreased together. In other studies, reductions in egg production performance associated with high densities were more pronounced for subordinate hens. Low ranking individuals experienced a higher reduction in welfare in high-density caging than higher ranking hens. Some researches suggest that the numbers of birds within a cage (more birds in a larger cage) is detrimental to bird welfare. Others suggest that density is far more important that the numbers of birds within a cage.
Summary
Higher-density (310 cm2/hen) caging reduces the productivity and welfare of the hens. Caging at lower densities (greater than 387 cm2/hen) does not appear to have an adverse effect on welfare when compared to floor pens, aviaries or get away caging systems. It is unclear if the numbers of birds within a cage has an impact on welfare.
Beak Trimming "Does it hurt"
Most poultry producers feel that beak trimming is an entirely necessary procedure to protect their flocks from excessive injury and mortality. On the other hand, the procedure has been described as unnecessary and painful mutilation. The scientific literature indicates that beak trimming reduces the aggressive activities of chickens in groups during laying. But, does it hurt?
There are nerve receptors in the beak that are sensitive to both pain and temperature in the range of 40 to 48 C. Behavioural studies assessing changes in feeding, drinking, environmental pecking, preening, head shaking, and time spent standing inactive and crouching in response to beak trimming have concluded that beak trimming results in pain. The ultimate question, which is very difficult to answer is "How much pain?". There is also a trade-off. In the absence of beak trimming, is the pain experienced by the bird due to vent and feather pecking greater or longer lasting than that which the bird would experience from beak trimming?
The effect of beak trimming on production and performance has been investigated. Some researchers have found significant increased rates of egg production with beak trimmed flocks while others have found no effect of beak trimming on egg production. Hen housed egg production in beak trimmed flocks may be improved due to a reduced number of injuries and mortalities resulting from aggressive behaviour. The effect of beak trimming on production differs between strains.
Beak trimmed pullets will tend to eat less feed and are often lighter in body weight during rearing. However, by the time of first egg, body weights have returned to normal. In some cases improvements in feed efficiency during the laying period have been reported. Studies of the effect of beak trimming on other performance traits such as egg weight, egg mass, albumen height, egg shell thickness and age at sexual maturity have yielded the conclusion that when done properly, beak trimming reduces mortality and results in minor or insignificant effects on performance traits. It is in the producers best interest to insure a high quality beak trimming procedure. The effects of improper beak trimming can be disastrous in terms of economics and welfare.
Beak trimmed flocks probably experience less stress over their production cycle compared to non-trimmed flocks. This makes sense as beak trimmed flocks show lower levels of aggressive behaviour. Beak trimming causes pain but it is very effective in reducing pain due to aggressive behaviours later in the life of the birds. What options to beak trimming do producers have? Genetic selection has shown some promise as an effective way of dealing with beak trimming in layers. However, it may be very difficult for primary breeders to incorporate selection for behaviour traits in a breeding program. Research into the effect of housing type, lighting programs, lighting source and bird density on aggressive behaviour is needed.
Summary
Beak trimming negatively affects the short-term welfare of layers. It is practised in order to ensure long term protection against aggressive behaviours in layer flocks.
Summarized from: D. L. Cunningham and J. M. Mauldin, 1996. Cage housing, beak trimming, and induced molting of layers: a review of welfare and production issues. Journal of Applied Poultry Research 5:63-69.
Source: Poultry Research Centre News - Vol. 5 No. 2, 1996
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