Housing for layers
Although the initial financial outlay involved in implementing new housing systems for commercial layers was costly in the short term, there are appreciable benefits in terms of eggs per hen, feed conversion ratios and mortality rates. Yet the biggest benefit of enriched cage systems, certainly in markets where consumers have a heightened sense of concern for animal welfare, lies in satisfying this awareness.
Awareness of the welfare of animals, including that of laying hens, began in the 1960’s and led to an aversion to eggs produced by hens housed in conventional battery cages. The European Union banned the use of battery cages beginning in January 2012, although this is yet to be fully complied with by all member states. This move resulted in the development of alternative housing systems for laying hens, and a renewed effort to develop alternative housing systems to meet all the requirements of good hen welfare. Each of the systems used have advantages and disadvantages that vary based on location, management, and genetic strain of the hens.
Conventional battery cages for laying hens were first developed in the US during the 1920’s to 1930’s. The system was developed to reduce the incidence of disease and parasites and also to reduce cannibalistic pecking. Cages makes management of the birds easier and requires less space than the other systems.
No bedding material is used in this system as the cages are suspended above the floor allowing the bird droppings to fall through the mesh floors and collect below the cages. As there is no litter to deal with this allows easy collection or clean-up of bird faeces. The system is the most economical of all currently used systems, with the best production, quality and efficiency. These cages are typically wire enclosures with sloped floors to allow the eggs to gently roll to the front of the cages making it easy to collect them.
Apart from the obvious advantage of protection from predators, cages also reduce the incidence of exposure to manure which can result in exposure to roundworm infestation and coccidia. When hens are reared in cages, there is a reduction in injurious pecking and mortalities because of smaller social group sizes in each cage. Due to the cage design there is lower incidence of dirty eggs. It is easier to monitor the health and wellbeing of each bird. There is a lower risk of contracting infectious diseases in caged housing systems compared to hens housed on litter, and the absence of litter means lower levels of ammonia, dust and bacteria.
The most obvious disadvantage is the restriction
of the natural behaviour of hens. They cannot dust-bathe or forage, there is relatively little or no space for them to walk around, they cannot flap or stretch their wings. Hens cannot wag their tails and nesting and roosting behaviour are not an option in these cages. It is possible for hens to get trapped between wires that can at times result in injuries. They can also damage toes from the breaking of overgrown claws in the wires of the cage floors. Feather pecking can also take place in the conventional cages, which often necessitates beak trimming.
Similar to caged housing system, these provide additional features in each house. These cages often include perches, a nest box and litter or an area where the hens can scratch. They also offer more space per hens allowing them room to walk around. The size and construction of the cages may vary with some cages having the capacity of holding up to sixty hens.
The major advantage of the enriched or furnished system is the environmental features it provides for the hens. The birds are able to engage in natural behaviours such as perching and nesting.
Substrate materials can be provided for birds to engage in dust bathing behaviour which improves feather condition. The presence of litter can reduce the incidence of feather pecking as hens can spend time foraging in the litter rather than pecking at their cage mate. When a nest box is available most hens will make an effort to lay in it and the number of damaged eggs is similar to that of the cage system. As with the conventional cages the enriched/furnished cages also offer protection from predators.
Disadvantages include the predisposition of laying hens to bone weakness results in more incidences of bone breakage and fracture due to increased activity in these cages. Also, the additional features in the cages have the potential to increase incidence of injury. Poorly designed perches can cause keel bone deformation and bumble foot. There is the potential for a negative impact on food safety because a portion of the eggs are laid outside of the nest boxes making them more likely to become soiled or cracked. Cracked eggs may promote egg-eating behaviour and eggs laid outside the boxes will require extra effort to collect.
Barns or aviary housing
These systems are quite similar as they are both sheds where hens are housed on an open floor. Hens have access to litter and nest boxes, while aviary houses have additional platforms or perches.
The major advantages of these systems are improved bone strength and plumage and lower levels of hyperkeratosis in birds that do not have access to perches. Hyperkeratosis is the thickening of the outer layer of the footpad caused by increased pressure load on the foot while perching or standing on wire floors. Hens in this system spend a lot of time walking and there are also increased natural behaviours such as foraging, dust bathing and comfort behaviours such as stretching wings and wagging tail. Hens are protected from predators
Disadvantages include an increased possibility of reduced health as birds raised on open floor are more likely to come into contact with pathogens in faeces. This may require handling of hens to administer treatment or vaccinations. As with the enriched/furnished cage system, hens that have access to perches are more prone to injuries. There is also more incidence of pecking which can result in increased mortality. This could be a result of increased numbers of social groups in the house. There is reduced air quality in litter based systems. Increased ammonia can result in eye problems such as keraconjunctivitis and can also have a negative effect on the respiratory tract.
Free range systems
Birds housed in this type of system have access to an outdoor area during the day. This area may be covered or uncovered. They are provided with an indoor area where they come in at nights and are able to roost.
Hens which are free ranged have the greatest range of natural behaviour and hence have better feather condition when compared to the other housing systems.
The main disadvantage of free range is that hens are exposed to toxins, wild bird diseases, predators and extreme climatic conditions.¡