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The science of farm animals

18 September 2009

Researchers in the Department of Clinical Veterinary Science’s Animal Welfare and Behaviour Group are developing techniques to assess an animal’s emotional state

Cherry: How do you assess an animal’s emotional state?

Mike: It’s very challenging, but one new approach that we’re developing is to train them that one cue, for example a tone of a specific pitch, predicts something nice such as food, and another cue, a different tone, predicts something less nice such as no food, or a noise. We then ask them – by presenting intermediate tones – ‘What do these ambiguous cues predict?’ We predict that animals in a positive emotional state, like happy humans, will tend to judge an ambiguous event as being positive – their proverbial glass is half full – and animals in a negative state with poor welfare tend to judge it negatively.


Cherry: It must be quite difficult to do.

Mike: It is technically quite difficult but currently it can be done in the lab under controlled conditions and early results are encouraging. Interpreting findings is difficult because of the problem of animal consciousness and whether animals really are experiencing emotional states in the way that we might. We can’t yet tell whether an animal’s apparent fear experience is similar to our fear experience, but the nature of that experience is probably similar in the context in which it happens.


Cherry: And do you test them physiologically?

Mike: There are many indicators of animal welfare, which include things like physiological changes – measuring levels of stress hormones, for example. Studies investigating the differences in welfare caused by the many different ways in which we keep or manage animals are often based on these kinds of measurements.


Cherry: Has this kind of work influenced decisions like that taken by the European Commission recently to ban battery cages for chickens in 2012?

Christine: Another approach that is used quite a lot is to actually ‘ask’ animals whether they want to be in a cage or not. Obviously you can’t ask them with a questionnaire, but you can give them choices and see how hard they work for particular things. The classic approach is to gradually put the price up. So you might find that a chicken in a cage is willing to ‘pay’ for more space by putting effort into pecking a button that makes the cage bigger. With animals you assume that what they want matches what they need, so assessing how hard they are prepared to pay for something, tells you how much they need it. It is this kind of work that has contributed to the ban on the conventional battery cage, because chickens will work very, very hard for a bit more space and also for a nest. So we continue to work on chickens – not just laying hens, but broiler chickens as well.


Cherry: How do you tell the difference between broiler chickens and laying hens when they are alive?

Christine: Well, in this country the broiler chickens are white and the laying hens are brown, but the broiler chickens we eat are basically enormous chicks. They are only five-and-a-half weeks old when they are killed, so they grow from tiny chicks to the size you buy them in the supermarket in an extremely short time. Laying hens, on the other hand, are skinny little birds that have been bred to be as small as possible and to lay eggs that are as large as possible. Over time, the size of the bird has gone down and the quantity of their food has dropped, but the number of eggs they produce has gone up. Consequently, all the calcium and nutrients go into the egg and there is nothing left to hold the bird together.

This highlights the other main issue in animal welfare: no matter how excellent your management is, if the animal is genetically selected for production at the expense of its body capacity, there is little you can do to improve its welfare. Our work shows that currently the broiler chicken falls into that category, as do some of the laying hens. There are now some fundamental questions being asked about how robust these modern geno-types are. We’ve probably gone too far in selecting for production. So when you go to the supermarket you should try to buy RSPCA Freedom Food assured chicken where only slow-growing birds are used.


Cherry: But what exactly are assurance schemes and how is your work related to what they do?

David: The Agriculture and Horticulture Development Board charges farmers, growers and processors a levy which, in the pig sector for example, is used – among other things –  to drive demand for quality pork and other pig meat products. This levy also means that the industry has money to spend on research and development. Since the industry wants to provide assurance to the consumer that their pigs are happy and healthy, it has developed assurance schemes, identified by the red tractor logo you see on some products. There is a system of inspecting farms to make sure standards are being adhered to, but the industry has realised that the system is not very good at assessing welfare on farms. They have therefore asked us to develop ideas of how this can be better assessed in order to provide better assurance to the consumer. This is an excellent example of taking the research that we do and applying it in a very practical sense.

Other work that we do is supported by charities and we have had a lot of funding from an organisation called Tubney Charitable Trust. They support activities that have a long-term, sustainable impact on the welfare of farmed animals. They funded our work on lameness in dairy cattle, example.


Cherry: What causes lameness in cattle?

David: It is a complicated mix of husbandry issues, like not having a comfortable lying area and not having the cubicles kept clean. In that instance, we knew the best way to approach the problem, but not how to encourage and support the farmer to change his husbandry system, and that is what the funding has enabled us to work on.

Mike: In summary, there are many other projects and forms of expertise within our group, particularly in the issue of slaughter and stunning of animals, where we lead the world in the development of systems that do it as humanely as possible. But the last point I want to make is that we try to provide a scientific basis for the decisions that government and society have to make about animal welfare. In doing so, we hope to give people a more level-headed and impartial view of the problem.

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