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EFSA Studies Poultry Welfare

A major study examined factors influencing welfare of broilers and broiler breeders

September 22, 2010
By Jim Knisley


The European Food Safety Authority (EFSA)’s panel on Animal Health and
Welfare has completed a major study and written a scientific opinion on
the influence of genetic selection on the welfare of broilers, and
another opinion on the influence of housing and management on the
welfare of broiler breeders.

The European Food Safety Authority (EFSA)’s panel on Animal Health and Welfare has completed a major study and written a scientific opinion on the influence of genetic selection on the welfare of broilers, and another opinion on the influence of housing and management on the welfare of broiler breeders.

The EFSA’s expert panel says most welfare concerns among broilers are linked to fast growth rates, a result of genetic selection in chickens. They also point to concerns about the interaction of genetic traits and the chickens’ environment, including housing and farm management. These opinions will be forwarded to the European Commission, which will prepare a report for the European Parliament.

Breeder welfare. The European Food Safety Authority (EFSA) notes that the degree of feed restriction has been increasing over the past few decades in response to genetic selection for higher growth rates, and recommends that birds requiring less feed restriction should be selected as future breeders, even if this may involve reduced selection pressure on high growth rates.

Data needed
The scientific opinion says that in the second half of the 20th century, the growth rate of broilers increased fourfold largely as a result of genetic selection. While welfare problems in these chickens are often attributed to genetic selection aimed at increasing productivity, genetic selection can also provide an opportunity to improve welfare and robustness, according the EFSA opinion.

Genetic selection of chickens now includes aspects related to welfare; however, improvements or otherwise in this area are difficult to quantify because solid data are not available, the opinion says. The EFSA’s panel said there is a need to develop and monitor welfare indicators in broiler flocks to measure welfare changes. They also stressed the lack of harmonized quantitative data in Europe to fully evaluate the impact of genetic selection, and the impact of the system of husbandry and management of broiler-breeders on birds’ welfare. They want systematic data collection and surveillance systems to be put in place.

The panel reviewed the scientific literature and also analyzed information gathered in consultation with stakeholders, such as the poultry industry, breeding companies, research groups and non-governmental organizations.

The major welfare concerns identified and associated with genetic selection for broilers were skeletal disorders leading to problems such as lameness, contact dermatitis, irregular body shape and sudden-death syndrome. These concerns are mostly linked to fast growth rates and lead to poor welfare. Broiler welfare could be improved, particularly if birds are genetically selected to withstand the environment they live in. For example, birds that grow more slowly should be selected for hot climates, as fast-growing broilers are susceptible to heat stress.

Regarding the genetic selection of chickens, high priority should be given to decreasing the number of lame birds and reducing contact dermatitis. These are important welfare problems that involve genetic predisposition and environmental conditions, the panel said.

Due to selection for fast growth and high muscle yields, breeders have a very high food intake. As a result, feed restrictions are necessary to limit growth rate to maintain good health. Experts recommend the competition for food (which can be observed among chickens when feed is not provided) should be minimized thereby reducing related injuries. Experts also recommend birds requiring fewer feed restrictions should be selected as future breeders.

Meanwhile, breeder companies can influence the welfare of broiler-breeders. There is a limited number of breeder companies that provide the various strains of broilers used worldwide. These companies provide the widely used guidelines for the housing and management of the grandparent and parent stocks, and have the opportunity to influence the welfare of
broiler breeders.

The following key points were considered in developing the scientific opinion – the housing and management of broiler breeders (parents and grand-parents), the health and welfare consequences, the use of indicators in practice and a risk assessment on the impact of housing and management on the welfare of broiler breeders, including genetic selection influences.

The panel also recognized that national legislation, regional climate or local traditions can lead to some specific differences between countries and companies. As a result, there is little overview and no quantitative data and on what husbandry and management systems are used in Europe. Housing and management of grandparent stock is, in general, similar to that of the parent stock, but with slightly lower stocking densities and greater emphasis on biosecurity and vaccination.

The panel also looked at what occurs at the hatchery.

At the hatchery, chickens that will become parent and grandparent stock are sexed and commonly vaccinated. “They may also undergo one or more mutilations (e.g. despurring, detoeing, toe clipping, beak trimming), which have been introduced to reduce injury to other birds in the flock, for example, feather and skin damage. Mutilations are carried out depending on the country or at the request of the customer, and it is recommended that quantitative information on the frequency of the different types of mutilations and the methods used in member states should be collected,” the panel said.

The consequences for welfare and the effectiveness of the practices are unknown, and some seem to have become routine for traditional reasons and may no longer be required, the panel reported. “It is recommended that no mutilation with an effect on welfare as severe as those resulting from cutting off toes or dubbing the comb should be carried out, unless justified by evidence for substantial and unavoidable level of poor welfare to birds.”

feed restriction
The panel also looked at feed restriction.

In general, the amount of feed supplied during rearing is restricted in accordance with set programs limiting growth rate and body weight to maintain good health and achieve desired levels of fertility, the report said. Although there is a lack of data on the effect of feed restriction, it causes welfare problems associated with hunger and leads to increased competition around feeding time, which may in turn lead to injured birds, the panel said. But not restricting feed intake will also cause welfare problems in standard birds because of the high body weights. Alternative feeding strategies, like diet dilution and/or appetite suppressants, do not clearly benefit broiler-breeder welfare.

There is a genetic component, as the degree of restriction necessary for mini breeders, for example, is lower than for standard breeding birds. Nevertheless, the degree of restriction has been increasing over the past few decades in response to genetic selection for higher growth rates. It is recommended that birds requiring less feed restriction should be selected as future breeders, even if this may involve reduced selection pressure on high growth rates, the panel said.

New indicators needed
The report also said that most of the research for welfare indicators has been carried out with broilers or laying hens. While the results of that research may also be used as indicators of welfare in broiler breeders, animal-based welfare outcome indicators for use during monitoring or inspection of grandparent and parent stocks, as well as for monitoring trends over time should be developed. For example, it is recommended that animal-based welfare outcome indicators related to feather and injury scoring should be developed and used to assess the level of damage related to aggression during mating, competition for feed and spiking (replacement of old males by young mature males in the flocks), the report said.

Housing of broiler-breeders must also be considered. Broiler-breeders need a physical environment that provides comfort and security, the panel said.

Perches may be a component of this, and they should be provided at an early age as it increases the chances of meeting the behavioural needs of the birds, as well as promoting learning to perch and using raised nest boxes. Sufficient perch/platform space should be provided during rearing, so that birds learn to navigate in a three-dimensional space, and later during the production period to provide space for all those birds that use them. Even if low percentages of broiler-breeder parent and grandparent stock in Europe are housed in cages, the cages shall fulfill the same requirements for litter, nest box and perches as agreed upon for laying hens. Environmental enrichment has been shown to be beneficial, compared to barren environments.

In general, commercial farms do not use any environmental enrichment, and more research is needed on the practical application of environmental enrichment, for example, cover panels for broiler breeders on European production farms. In broiler breeders, there is no systematically collected data on health issues such as leg disorders and contact dermatitis, so their exact prevalence is not known. Even though leg weakness is not commonly observed due to the feed restriction, the same musculoskeletal lesions as those observed in broilers have been reported in broiler breeders. The prevalence of leg weakness and contact dermatitis could be monitored using modified versions of the standardized scoring systems developed for broilers. There is also a lack of surveillance data for many infectious diseases. However, deviations from normal water and feed up-take (time, pattern and amount) are interpreted as the first indicators (early warning) of possible disease, the report said.

The panel concluded that the top five overall welfare hazards according to risk scores were barren environments, high stocking density, fast growth rate, feed restriction and low light intensity. These five hazards were ranked highly, because either the adverse effects are intense and/or prolonged, or the probability of the birds being exposed to these hazards is high and the probability of experiencing adverse effects when exposed to these hazards is high. A hazard’s risk score ranking does not necessarily correlate with its welfare impact or magnitude ranking (although there is reasonable similarity between the risk score and welfare impact profiles).

The magnitude and welfare impact scores for the categorical groups (production and rearing, males and females, fast and slow growing) of broiler breeders were estimated. The trend in the top five for these different categories were similar, despite the groups being chosen specifically because of their differences. In the assessment process, greater uncertainty was identified in the conditional probability of exposure than intensity. This is likely to be a true reflection of knowledge in the field, as there is relatively more information available describing adverse effects, their intensity and duration, than there is quantifying how extensive the problem is. It was recognized by the experts that probabilities vary from region to region, country to country and between different types of farming system, and so probability estimates consequently had large ranges. The lack of good data is a concern, and routine data collection across Europe would help to make these estimates more accurate, the panel said.