
1999
2ND PLACE

How to get into the mind of a chicken
By
Andrea Lord 
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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