Chapter 4.8 on Food safety affected by different production systems (Microbiological and Chemical hazards) was jointly adopted by the BIOHAZ Panel on 21 October 2004 and the CONTAM Panel on 1 February 2005 respectively
EFSA was invited by the EU Commission to draw up an opinion on the welfare aspects of the various systems of keeping laying hens described in Council Directive 1999/74/EC and enriched cages in particular. The implications of these systems towards obtaining safe eggs for consumers were also to be considered.
This opinion was adopted by the Scientific Panel on Animal Health and Welfare (AHAW) on its Plenary Meeting held on 10th and 11th November 2004. The chapter on “Food safety affected by different production systems (Microbiological and Chemical hazards)” was jointly adopted by Scientific Panel on Biological Hazards (BIOHAZ) on 21st October 2004 and Scientific Panel on Contaminants in the Food Chain (CONTAM) on 1st February 2005 respectively.
According to the mandate of EFSA, ethical, socio-economic, cultural and religious aspects are outside the scope of this Opinion.
In the current Directive (1999/74/EC) the terminology for housing systems of laying hens is confusing. In order to be clear, throughout this opinion, the terminology “laying systems” is used to refer to those systems in use for the housing of adult egg laying hens instead of ”rearing systems” (terminology used in the Directive) that is generally understood to refer to housing systems for the rearing/growing of hens from one day old until about 18 weeks of age when they are moved to the laying house. The term "alternative systems" is used in the Directive to refer to any non-cage system.
The term "alternative systems" is used in the Directive to refer to any non-cage system. In the industry the term is used to refer either to systems which are not conventional cages or to any non-cage system. A cage is considered here to be a system which is operated without the human keepers entering it. All other systems will therefore be referred to as "non-cage systems". The three categories of systems for housing laying hens considered in this opinion are conventional cage systems, furnished cage systems (called enriched cage systems in EU Directive 1999/74/EC) and non-cage systems (called alternative systems in Directive 1999/74/EC).
Animal welfare science is a rapidly expanding area and there have been major methodological and conceptual advances in this area since the Scientific Veterinary Committee, Animal Welfare Section, published the ”Report on the welfare of laying hens” in 1996. There has been increasing agreement that there are several useful methods which should be taken into account when assessing welfare. There advances in knowledge in hen welfare have included in particular behavioural priorities, prevalence of injuries, and pain perception. Animal health and physiology are still very important areas of research on animal welfare, but to these one can add the increasing role of neurobiology in basic animal welfare research and a striving after objective ways to integrate several different measures of animal welfare into a single overall estimate.
It is generally accepted that when assessing the welfare of animals in different housing systems and attempting to come to overall conclusions, the most trustworthy method is by combining measures from different disciplines and different approaches. It has been shown that despite diverse starting points there is often considerable agreement on key issues amongst experts.
The problem of how different indicators should be weighed against each other to come to a final conclusion as to whether or not the housing system promotes good bird health and satisfies the behavioural priorities of the bird is difficult, since there is still no generally accepted methodology for such integration of indicators. For this reason, conclusions and recommendations refer to pros and cons of the different laying systems, specifically referring to how the birds themselves may experience the various systems in which they are kept.
Research in the 1990s showed that welfare could be good in aviaries and other non-cage systems but that it was difficult to avoid outbreaks of injurious pecking without beak-trimming. Commercial experience has supported this position.
Recent research and development and commercial experience of systems have led to considerable improvements in design of systems, particularly furnished cages, and improvements in knowledge of how to manage birds in furnished cages and non-cage systems. These have solved some of the problems that existed at the time of the last report.
Housing systems for hens differ in the possibilities for hens to show species specific behaviours such as foraging, dust-bathing, perching and building or selecting a suitable nest. If hens can not perform such high priority behaviours, this may result in significant frustration, or deprivation or injury, which is detrimental to their welfare.
Injurious pecking is a serious problem in many systems and is especially difficult to control in large group furnished cages and in non-cage systems. The problem can be minimised by appropriate housing and management as well as genetic selection.
Beak-trimming is a painful procedure. At present, the least pain-inducing method of beak-trimming, involves very young birds.
Some of the most severe threats to bird welfare in the various systems are:
In Conventional Cages (CCs)
- Low bone strength and fractures sustained during depopulation.
- The inability to perform some high priority behaviours including nesting, perching, foraging and dust bathing.
In small Furnished Cages (FCs)
- Feather pecking and cannibalism in flocks with non beak trimmed birds
- Depending on lay-out some high priority behaviours (e.g. foraging, dust bathing) can not be performed or are limited.
In large Furnished Cages (FCs)
- No data available on relevant issues like bone fractures, feather pecking and cannibalism.
In Non-Cage systems (NCs)
- Bone fractures sustained during lay.
- Feather pecking and cannibalism in flocks with non beak trimmed birds.
- If an outdoor run is provided for birds in Non-Cage systems, there is additionally a high risk of parasitic diseases.
Hens should be provided with sufficient space to allow the movements described above to be carried out by each bird taking into account the presence of other birds and the frequencies of exercise and other activities required by the birds to avoid significant frustration, or deprivation or injury.
Injurious pecking should be minimised by appropriate housing and management as well as by genetic selection. Wherever possible, this should be achieved by provision for the hens’ needs, including opportunities to avoid birds which carry out the pecking, rather than by beak-trimming. Any beak-trimming should be by the least pain-inducing method, and beak-trimming should be permitted only if significant amounts of injurious behaviour would otherwise result.
Keeping birds outdoors presents a risk of exposure to a greater range of infectious agents compared with birds kept only indoors due, for example, to exposure to wildlife including insect vectors. The possible consequences of exposure, infection and transmission, are likely to be different depending upon whether the birds are kept indoors or out, and the specific management systems. Where housing and management conditions are poor, infectious agents, mainly bacterial, may have favourable conditions to develop and create chronic disorders for example respiratory problems.
The level of downgraded (grade B) eggs depends on the design and management of system. Although reported percentages of downgraded eggs and especially dirty, broken and cracked eggs, are often higher when laid in furnished cages and to a greater extent, in alternative systems, considerable improvements have been observed recently and further advances can be expected, especially in Furnished Cages.
In general, the level of bacterial eggshell contamination seems to be higher on eggs laid in Furnished Cages than in conventional cages. In alternative systems, this level is even higher and seems to be related mainly to a higher microbial load of the internal environment of the laying house.
There is limited information on the proportion of eggs contaminated and the level of contamination, with zoonotic bacteria, related to the methods of production. Of these, Salmonella Enteritidis dominates in eggs, raw egg materials and egg products, and can be present on the eggshell and in the yolk of eggs. In theory, the risk of contamination with Salmonella spp. and particularly with Salmonella Enteritidis might be higher when eggs are produced in some non-cage systems, because of the greater exposure of layers and their eggs to environmental contamination.
There are reports showing higher levels of dioxins and of dioxin-like PCBs for eggs produced in free range systems (including organic farming) than for eggs produced in cage systems. It is unlikely that contamination of animal feed is the origin of these higher levels, because EU feed regulation is equally applicable to all production systems. This implies that additional sources of contamination are present and special attention should be given to identify these sources of exposure