By Andrea Lord

How to get into the mind of a chicken

DO YOU feel guilty when you bypass the expensive free-range eggs or chicken at the supermarket? If so, give yourself a break - at least for now. The truth is we don't know that free-range systems result in happier chickens; such birds are more likely to become diseased and attack each other than those farmed using cheaper, more intensive methods.

Intensive farming of hens in battery cages for eggs, and broilers in crowded, dim sheds for meat, causes problems of its own. Chickens evolved from red jungle fowl, which go about in small groups among dense jungle undergrowth. Such an environment differs greatly from both free range
(in which relatively large flocks are housed in open spaces) and intensive husbandry systems.

Despite their bodies being specialised to produce either eggs or meat, the minds of chickens and hence the way they socialise, their preferred physical environment, and what frightens them - are probably still largely adapted to jungle conditions. It's unlikely that we can ever replicate such ideal conditions on farms while the demand for omelettes and chicken korma remains, but we can find out what chickens really like or, more realistically, what they really hate.

Measuring the internal experience of an animal is central to the science of animal welfare, and a tricky subject, but one that my team in the animal behaviour research group at Oxford, in collaboration with scientists from the universities of Glasgow and Washington, are tackling. Humans, chickens and other animals all release hormones known as corticosteroids when they are frightened, stressed or otherwise aroused. Corticosterone, the chicken version of the hormone, can be measured in blood samples, and shows promise in being one of the signs we can use to monitor the mental health of chickens.

However, blood sampling can be pretty stressful for a chicken, and the resulting rise in corticosterone levels has interfered with the results of many previous studies. An alternative, less disturbing, way to measure hormones is in the droppings. By analysing the droppings of chickens from both intensive and free-range systems, I hope to discover whether the husbandry system influences corticosterone levels, and to relate this to the welfare of the birds. Another promising way of measuring hen happiness without harming the chicken is by looking at eggshell quality. Although hens will continue to lay even under sub-optimal conditions, certain characteristics such as shell density change when hens get a fright.

By measuring eggs from different husbandry systems, my team plans to investigate whether such changes occur only in response to short-term stressors, such as vaccination, or whether they are also an indicator of long-term welfare. One problem with using corticosterone as a welfare indicator is that it is also released during times of excitement people riding a roller coaster are likely to be releasing corticosteroids like mad, yet many would classify their experience as positive. Similarly, pleasurable events may raise hormone levels in chickens, and also cause eggshell changes.

To distinguish between ''good'' and ''bad'' causes of elevated corticosterone levels and shell changes, we can ask the birds if they enjoy the chicken equivalent of a roller coaster ride or boxing match.

THIS is done with choice tests, during which a chicken's preference for one environment over another is determined by how long it spends in each, and by whether it will surmount obstacles to obtain certain environmental qualities. In this manner, we avoid imposing on chickens our view of what is good for them; they may have completely different desires from what we imagine. For example, in the past a recommendation was made to the Government to ban the fine-wire mesh floors of battery cages in favour of a more solid alternative, but when given the choice, chickens clearly preferred the old type. These small steps towards unravelling the mystery of the chicken's mind may help us to design husbandry systems that maximise chicken welfare and still produce enough eggs and meat to satisfy consumer demand. The prices on the supermarket shelves may rise as a result, but at least shopperswill know that the birds are getting the benefit.

Andrea Lord, who is at Merton College, Oxford University, came second in the older category of the Young Science Writer competition, run by the chemical company BASF and The Daily Telegraph with the backing of the British Association for the Advancement of Science.

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