Poultry Welfare in the 21st Century

Bas Rodenburg’s focus is to optimize breeding, rearing and management strategies in laying hens to prepare them for life in a complex large flock, non-cage environment. His research is coupled with dialogue with the industry to see what actually works

With the ban on conventional cage systems in Europe in 2012, the same birds that once lived in cages of four are now living in groups of 30 to 100 birds in furnished cages or up to 6,000 birds in open systems. A further ban on beak trimming, already in place in Scandinavia, Switzerland and Austria, will come into force in 2018 in the Netherlands.

For Bas Rodenburg, assistant professor at the Behavioural Ecology Group at Wageningen University in the Netherlands, these restrictions have created a sense of urgency to mitigate specific welfare issues with all systems: feather pecking, cannibalism, keel bone fractures and smothering.

Rodenburg’s focus is to optimize breeding, rearing and management strategies in laying hens to prepare them for life in a complex large flock, non-cage environment. His research is coupled with dialogue with the industry to see what actually works.

The transition from caged housing systems has been both positive and negative, Rodenburg told the audience at a lecture hosted by the Campbell Centre for the Study of Animal Welfare at the University of Guelph. Birds now have more space, access to a nest and perch, and some litter for scratching and dust bathing. The negative? The birds are more challenging to manage, with the possibility of problems and panic reactions spreading through the entire house.

Severe feather pecking is a common issue related to normal foraging behaviour that is then re-directed to other birds, said Rodenburg. It is more likely to occur with more sensitive birds, especially if there are external stresses: the birds don’t sleep, become agitated and the result is feather pecking.

This behaviour has a strong genetic component. Rodenburg pointed to a PhD thesis done by Elske De Haas at Wageningen University in the Netherlands, investigating if there could be less feather damage by selecting birds that were less easily stressed?

Of the two genotypes studied, Dekalb White birds were more sensitive to stress, while ISA Brown cross birds were more sensitive to the environment, said Rodenburg. Basically, there was more to be gained in white hens from selection for decreased stress sensitivity and more to be gained in brown hens from changes to the environment.

What about feather pecking during rearing? Rodenburg says this behaviour appears at five weeks of age, both gentle feather pecking, where the victim doesn’t move away, and severe feather pecking, which usually develops as an adult. Coincidentally, five weeks of age is when birds are usually set free in rearing systems.

Since feather pecking is re-directed foraging behaviour, Rodenburg said litter is of key importance: giving them forages or litter can help re-direct their pecking. De Haas’ research has shown that if litter is disrupted or limited before five weeks of age, an increase in feather pecking will result at 40 weeks of age. Rearing systems where the chicks hatch, drop down into litter and have immediate access to feed and water – as Rodenburg says, “get on with life” – may be favourable for their early development.

At 40 weeks of age, four feather-pecking factors remained significant. During rearing, those that displayed high feather pecking at five weeks continued to do so at 40 weeks; birds showing a high fear of humans were also more inclined to feather peck. During the lay, there was more feather pecking damage in floor houses – older systems – than in aviaries; larger groups also had more damaged feathers.

Where birds were considered high fear, Rodenburg suggested habituating the birds to different people or different colour clothing to reduce stress. He also noticed that feather pecking was more of an issue where farmers had not modified their management – those that fed alfalfa hay, turned on the radio or supplied pecking blocks had fewer feather-damaged birds.

Rodenburg offered four solutions to reduce feather pecking, beginning with further exploring novel methods of group selection such as the white/brown difference. Reducing the fear and stress to the parent stock can be accomplished by exposing the birds to more people. During rearing, continuous access to litter, especially at five weeks of age, should reduce feather pecking; and for laying hens, continuous access to litter remains important. He also suggests that assessing the fear level of the birds at five weeks can be used as a predictor of later behaviour.

At all links of the chain, Rodenburg points to management factors such as feed composition and quality, litter quality, and limiting fear and stress to reduce the incidence of feather pecking.

What about keel bone fractures? It’s a new problem, said Rodenburg, but the major causes remain unclear. One Swiss study has shown moderate to severe deformities in six to 48 per cent of birds, and including slight deformities increases the incidence of fractures to 83 per cent. Do they physically just have a lot of accidents, hitting the cage system with their keel bone? Is it about bone health? Layers deposit a lot of calcium into their eggshells that may lead to weaker bones. Both hypotheses could be right, said Rodenburg.

In his study from 2008, Rodenburg found that 62 percent of birds had minor fractures in furnished cages compared to 87 per cent in non-cage systems. How do minor fractures affect welfare? That’s another area to explore, said Rodenburg.

Housing system characteristics may be a factor as well. Using wire floors increased the incidence of fractures versus plastic floors, in the work of PhD student Jasper Heerkens at the ILVO in Ghent, Belgium. Was plastic a better landing surface? Yet another area where more research is needed, said Rodenburg.

Work done by Ari Stratmann in Bern, Switzerland, suggested that extra ramps in aviary systems resulted in less fractures, as did soft perches. Her genotype selection work proposed that selection for stronger bones resulted in fewer fractures but poorer egg quality. Can we find a balance, asked Rodenburg, or use nutrition to accommodate the difference? Research is also now studying training the birds to use new, complex, three-level systems to reduce fracture rates.

Smothering is another welfare issue that is seen in non-cage or free range systems. The birds at the bottom can die. “It’s difficult to tackle because it’s difficult to predict,” said Rodenburg. Smothering is not as big an issue with white hens that tend to be more agile and keep a larger personal space, as opposed to brown hens that are more likely to aggregate.

As a possible solution, Rodenburg described the “Eyenamic” monitoring system, developed for broilers, that measures normal aggregation activity for the flock. An alarm will sound if the flock deviates from normal, providing a practical way of knowing when something is wrong.

Do individual birds affect the social dynamic of the whole flock? De Haas found that having a fearful, highly active bird in a group affected stress-sensitivity of the group members.

Chicks brooded with a foster mother are less fearful, perform more ground pecking, and perform less feather pecking; but how can this be applied commercially? Do changes in rearing affect brain morphology, encouraging lasting changes, similar to the changes found in birds reared by a mother?

Light exposure during incubation may be a factor in producing less-stressed chicks. Does light at specific stages result in more gentle feather pecking? A recent study by Archer and Mench (2013) suggests that 12 hours of light and 12 hours of dark during incubation created favourable effects in broilers, possibly through increased brain lateralization.

Commercial incubation may also involve high noise levels. When chicks hatch they communicate with each other but in a commercial setting they can’t hear each other. Rodenburg suggests that the hatch window could possibly be reduced if the chicks could communicate, reducing the time they need to spend in the incubator. In a study where chicks from one to 17 days old were monitored, quiet chicks were more synchronized, emitting lots of social vocalizations. He can only speculate about how this affects their later behaviour. This is currently being studied in Wageningen.

There are still many questions. For all welfare issues we want to better understand the group social dynamics and how to manipulate them, said Rodenburg. The ultimate goal is to rear laying hens that perform well in non-cage systems.