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Animal welfare and food security
Research highlights from the BBSRC Animal Welfare Programme
25 May 2011
The UK is home to the largest sheep farming industry in Europe. There are five million pigs on UK farms at any one time. 16M chickens are produced for the dinner table in the UK every week, and a jaw-dropping 51Bn chickens were slaughtered in the world in 2009 (ref 1) – more than seven for every living person on the planet.
In the drive to produce ever more meat, many people are worried that animal welfare concerns are lost or not properly addressed in the seemingly relentless drive to increase the productivity and efficiency of pig, sheep, cattle and poultry rearing in particular.
Do count your chickens…
Image: US Dept Agriculture
Many people feel that good farming begins with good animal husbandry, and that the welfare of animals should be an integral part of farming that should not take second, third or fourth place to productivity or profit. The BBSRC Animal Welfare Programme (AWP) focused research to better understand the science of animal welfare so we can more accurately identify factors that can improve (or reduce) an animal's quality of life.
Launched in 2005, the five-year £8M programme is comprised of three research strands involving researchers from four UK veterinary schools in the Universities of Edinburgh, Glasgow, Bristol and the Royal Veterinary College, and associated institutions including the Scottish Agricultural College, the Roslin Institute and the University of Oxford.
Measure by measure
First things first – how do you measure animal welfare? Accurate and meaningful measurements lie at the heart of science and the development of welfare assessment tools that can be used on farms, as well as in labs and zoos, is essential for the development of animal welfare research.
But quantifying animal welfare is notoriously difficult. Selecting factors to measure must avoid assigning human values (anthropomorphising) or attributes to the animal and qualitative findings are often not what was expected. For example, some chickens prefer an environment with a wire floor rather than the wood shavings that we might expect them to prefer.
The sun doesn't always shine… so how do you measure animal welfare?
Image: Scottish Agricultural College
There are two main approaches to assessing animal welfare. 'Welfare indicators' rely on behavioural, physiological and physical responses to housing and management practises as indicators of an animal's welfare – whether a chicken has glossy feathers or normal preening behaviour for example. The 'motivational priorities' approach, on the other hand, assumes that animals can make judgements about which environment is best suited to their welfare and this can be measured by giving animals choices in the lab and observing their preferences.
Research under the AWP has attempted to tie these two strings together. Professor Christine Nicol at Bristol University and colleagues housed chickens for two to five weeks in different environments and measured the birds' physical, physiological and behavioural responses to each setting along with the birds' preferences.
Using sophisticated hierarchical statistical modelling techniques that account for bird, group and order effects, the results indicate that it is possible to connect welfare indicators and motivational factors. For example, an environment (of any type) was more likely to be chosen when birds previously housed in it had shown more preening behaviour, lower fear-related behaviours, and lower levels of some physiological stress parameters (corticosterone, glucose, heterophil:lymphocyte ratio, faecal moisture).
For the first time, this provides evidence that some behavioural and physiological welfare indicators are linked to motivational priorities. Conversely, other indicators, such as mild plumage damage, proposed as potential measures of welfare by scientists, do not seem to reflect the views of the chickens themselves. This work is helping scientists to choose a refined set of indicators that really do measure welfare.
Nicol says it is essential to study motivational priorities as this gives us insight about what matters from the animals' point of view. "But this information is often difficult and time-consuming to obtain," she says. "Once we know how more 'easily-measurable' welfare indicators link with motivational priorities we take a big step forward in animal welfare science."
Applying research on a commercial scale is still a challenge. Hence, other programme research aimed to build an automated system to assess chicken welfare that was cheap, robust and compact enough to be routinely used on commercial farms.
Continual monitoring could bring welfare benefits. Image: M. Dawkins
Professor Marian Dawkins and colleagues at the University of Oxford developed an automatic, real-time monitoring system that used optical flow algorithms – a measure of the movement of an image across a camera – to track changes in the movement patterns of chicken flocks (ref 2). They found that flocks with welfare problems, namely a high proportion of birds with poor gaits, could be identified using the optical flow system because they move differently from healthy flocks.
The results suggest that technology that utilises automated optical flow-type measures could be effective and enable continual, non-invasive and non-intrusive monitoring; trials are underway with two major commercial producers.
The system could have advantages because at present broiler chicken flocks are often assessed by examining the birds' feet and legs at the point of slaughter – after welfare concerns could be addressed for animals in distress (ref 3). The more expensive alternative is for people to visit barns and calculate a 'gait score' for the flock, but there is a case for reducing human-chicken interactions between different barns and across farms to manage the risk of spreading diseases.
Dawkins stresses that the system is not designed to replace the stock people who visit barns and inspect chickens. "Stockmanship is one of the most important elements of good welfare. We are trying to develop a system that supplements rather than replaces good stockmanship and makes it possible to monitor birds continuously."
Beyond the qualitative welfare measurements as an animal is raised lie interesting and undoubtedly significant new discoveries that may change the way that we perceive the fundamental notions of growth, maturation and development.
For some years, researchers in a wide variety of fields including veterinarians have noticed that conditions that animals such as pigs, poultry and sheep experience in their first months of life, or even in the womb, can have long terms affects on their welfare – changes that might even be heritable too.
Thanks Mum: maternal welfare can affect offspring welfare.
Image: Scottish Agricultural College
Research on rats at the University of Edinburgh, designed to complement ongoing research on pigs in the Scottish Agricultural College and the University of Glasgow, demonstrates that pre-natal exposure of a mother to stressful stimuli can affect traits in its offspring that relate to how sensitive offspring are to stress and pain, and for females how well they cope with being a mother. Such long term effects of exposure to adverse circumstances experienced by the mother are together designated 'programming'. This involves setting of mechanisms in the brain that organise hormonal and behavioural coping responses to stress or pain, so that these mechanisms are more or less reactive.
Programming may involve subtle changes in the ways that neural connections in the brain are formed, as well as changes in the levels of activity of specific genes in the brain. This latter process is described as epigenetic modification of the genome: when the physical characteristics (phenotype) of individual cells, tissues and the whole organism is the result of the genes switching on and off as the early embryo and then foetus develops. This process can be influenced by external factors so that some genes may be switched off, or kept on when normally off – the consequence is a re-programming of normal gene expression.
Why is this relevant for animal welfare and food security? Because research has shown that an animal's long-term welfare can be compromised by their mother's experiences when pregnant. For example, Professor John A Russell and colleagues at the University of Edinburgh and the Scottish Agricultural College have shown that pigs (and rats) exposed to pre-natal stress are more vulnerable to experiencing heightened stress and showed altered pain responses compared to control animals. The greater sensitivity to pain in the offspring is most evident when prenatal stress is followed by a peripheral inflammatory injury, as may follow tail-docking in farmed pigs for example. Whether or not to tail-dock is a decision that balances several different factors to determine what will be best for a particular animal's welfare. Knowing that prenatal stress makes piglets more sensitive to pain will be valuable additional information for farmers making such decisions.
There is also evidence that if a (pregnant) sow is stressed and a poor mother the female progeny also turn out to be poor mothers; this could be a result of the programmed mother's maternal behaviour style, but intergenerational epigenetic factors may also play a part.
A similar effect has been found in chickens, where incubation conditions can affect traits in offspring. Professor Neil Stickland of the Royal Veterinary College (RVC) and colleagues treated eggs over four days with high/low temperatures or mechanical manipulation and monitored birds until commercial slaughter age. His team noted changes in feeding behaviour, body growth rates, tissue mass and gait parameters and says that neglecting epigenetics "could overlook potential animal welfare issues".
In sheep, exposure to a bacterial toxin could affect future generations:
Image: Scottish Agricultural College
Research at Bristol Veterinary School by Dr Corinna Clark on lambs has shown, too, that stress in early life in the form of a single exposure to a compound from E. coli bacteria can compromise welfare later in life and may have implications for following generations. "It is therefore important to gain a better understanding of long-term and potentially epigenetic effects, as welfare could be compromised beyond any initial illness or stressor," says Clark.
The conclusion regarding welfare from these studies on programming are that the environment in which animals are kept during pregnancy is of major importance in the sensitivity of the offspring to stress and pain. Furthermore, even if conditions are improved for the pregnancies of the programmed offspring, the programming may persist for the next generation. It may take a couple of generations after an environmental improvement before the programmed traits fade away, and an improvement in welfare indicators is seen.
Hence, welfare research shows that good animal husbandry does not begin just when an animal is born, but before. Careful planning of optimal conditions for animals throughout the production cycle could save on welfare costs and productivity losses later in life, although we know little about how positive postnatal conditions could counter negative factors experienced earlier in life (or even before).
In addition, this type of animal welfare research is expanding our understanding of the underlying biology of growth, development and behaviour. Furthermore, because it takes place in mammals, the findings in areas such as stress reactivity, immune function, emotional and pain experiences are relevant to human lives and lifestyles.
Animal welfare farm
The goal of animal husbandry is common to most developed countries: how to devise systems to produce food sustainably with compassion. About a billion farm animals are raised annually in Britain (ref 4): do they all have a life worth living?
A new experimental facility, the Animal Welfare Barn, was built at the RVC and houses unique capabilities to control and monitor an animal's physical environment. The barn has automated systems to manage light, heat, sound and air as well as food and water supply across 10 identical rooms. Growth can be monitored continuously and behaviour automatically with images stored digitally for later analysis. Hence, the facility offers immense scope for the study of nutritional or genetic effects of disease, environmental parameters such as ammonia levels (from urine and faeces), as well as behaviour, perception and cognition.
The Animal Welfare Barn can control important environmental parameters. Image: RVC
"The welfare barn is a good way to investigate animal welfare because of the environmental control it allows," says Dr Soibhan Abeyesinghe at the RVC. "We can scale up experimental work within the same facility; mimicking a section through a livestock barn while maintaining the degree of environmental control such that we can avoid some of the variability introduced by working on different commercial sites."
This state of the art facility has already led to published papers (ref 5) in more than 12 journals; key findings include understanding the capability for group-mate discrimination in hens, and the environmental effects on social behaviour in laying hens and growing pigs.
For example, hens do not form specific individual positive social bonds; nor is social stability disrupted by the physical environment. Researchers also found an unexpected tolerance of chronic exposure to atmospheric ammonia by broiler chickens and growing pigs (ref 6, ref 7) from measurements of gene expression – this tolerance is not seen in their behaviour which appears to indicate at least short term stress occurring under commonly experienced levels of atmospheric ammonia (20ppm, compared to 5ppm).
The facility has also enabled studies on the optimisation of two or more interacting agricultural processes, such as growth and ammonia emissions, or light levels and noise, which are critical production factors in production in the poultry industry. In this way the facility, and animal welfare research in general, can promote positive and avoid negative animal welfare issues as agriculture intensifies to meet the global challenges of achieving food security.
- FAO STAT (external link)
- Optical flow patterns in broiler chicken flocks as automated measures of behaviour and gait (external link)
- ‘Ingenious’ animal welfare monitoring technique (external link)
- Understanding Animal Research – Animals and society
- Centre for Animal Welfare – selected publications (external link)
- The impact of chromic environmental stressors on growing pigs, Sus scofra (Part 1): stress physiology, production and play behaviour (external link)
- The impact of chromic environmental stressors on growing pigs, Sus scofra (Part 2): social behaviour (external link)
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