The Australian egg industry has seen a large shift in the proportion of chicken eggs coming from non-cage systems, especially free range. There is little doubt that some of this has been driven by consumer and retail demand. But some has been the result of new cage regulations introduced in 2008, which led producers to modify their cage facilities to free range and barn production. By removing cages, they avoided the high costs associated with new cage refurbishment.
This has left the industry with a wide range of very different facilities designated as “free range production units”. In its simplest expression, we could say free range provides birds with a range area. But if you’re interested in bird welfare, you should be asking what role bird density in the range area has on hen well-being.
This question has initiated strong debate in the egg industry, but what do we really know about the relationship between range density and hen welfare? A search of the literature suggests, not a lot.
Research efforts have been directed at comparing welfare of birds maintained in different housing systems. These look at measures such as behaviour, stress, health, plumage condition, biology, body injuries and mortality.
The EU had a directive that conventional cages were to be banned from 2012. There was a rapid movement to floor based systems - such as barns and aviaries - especially in countries which implemented their own ban on conventional cages earlier than 2012. This rapid transition did, to some extent, leave researchers lagging behind in their efforts to evaluate welfare of hens in these facilitates. It is now obvious that floor based systems have a range of issues associated with hen welfare that need to be further researched.
Whenever hens are housed in groups, there will a range of social interactions that occur. There will always be competition for space. The size of the group will influence aggression and recognition within the group. If resources - including space - are limited, competition for these can be intense.
The intensity that hens exert in an effort to maintain a larger space is not great. However, when provided with alternatives, they appear to prefer increased space. This could suggest that hens will do without some comfort activities - such as dust bathing, scratching and wing flapping - if they have to make a large effort to get the space needed to perform them. Collectively, these observations indicate that the effects of stocking density are complex.
Most studies on stocking densities have use small scale facilities with changes in group size or floor area. They are often conducted in enclosed sheds such as barns and aviaries. Such studies may lack some relevance in large commercial facilities because of differences in the degree of aggressive behaviour.
It has been reported that hens are can only identify about 100 individuals in a group, and that they prefer to be with familiar hens rather than unfamiliar hens. This would imply that constantly changing group dynamics in large production units might create increased stress.
The density of the free range area is likely to have an influence on the degree of social stress. However, farmers don’t have total control over how densely hens are gathered. The way hens move from the housing unit to the range area, climate, management and the positioning of resources (such as shade) in the range are all going to influence the density of hens in various parts of the range and hen house.
While it’s probable that the maximum densities in particular areas of the free range system are going to have more influence on hen welfare than the average range density, we don’t know for sure because there are no scientific studies performed under Australian conditions.
The model code of practice identifies 1500 birds per hectare as the upper density limit but this has not been validated by scientific evaluation. For an informed debate as to what is an appropriate density in free range production systems more scientific evidence is needed.
While debate about a suitable density for free range systems continues, there remains another consideration which is often left to one side. Egg production systems produce different environmental footprints. A farm’s nitrogen and carbon production and the energy it uses will depend on the farm management, hen housing, manure handling and so on. There is meagre information concerning the environmental footprint for various production systems; it’s an area where more research is needed. There are environmental legislative constraints that need to be considered when deciding how to use the range area.