Appetite Genes Are Key To Better Poultry Diets
The welfare
of poultry could be improved by a discovery about how chickens regulate
their appetites. Scientists have identified how a chicken's genetic
make-up can affect the signals sent from its stomach to its brain that
tell a chicken when it has had enough to eat.
Poultry farmers
often have to restrict food for chickens because some birds are
insensitive to feelings of fullness and can overeat, affecting their
ability to reproduce.
The study could make it easier to develop methods to develop diets that reduce excess growth more naturally in these birds.
Researchers say
that genetic differences, which affect when chickens recognise when
they have had enough to eat, could date back thousands of years when
chickens were first domesticated and breeds were selected for their
size.
The research
was carried out by The Roslin Institute at the University of Edinburgh.
Dr Ian Dunn, who led the study, said: "The findings shed greater light
on food intake in birds and help us understand why some breeds - in
general the faster growing types of chickens - are more insensitive to
feelings of fullness than others."
The study,
published in the American Journal of Physiology, Endocrinology and
Metabolism, focused on a protein called cholecystokinin (CCK) that has a
key role in sending signals linked to being full from the gut to the
brain.
The
researchers, funded by the Biotechnology and Biological Sciences
Research Council, found that some birds were better equipped than others
at recognising the protein, making them more effective in triggering
signals of feeling full.
The study
involved cross-breeding a fast-growing meat production strain of chicken
with a relatively slow-growing, chicken. The researchers looked at how
the protein was processed in both types of chickens and in the new cross
breed.
They showed that reduced levels of protein that recognises the fullness signal also affected the chicken's natural body weight.
Their findings
back up the theory that, when poultry were domesticated thousands of
years ago and bred for increased size, their appetite levels were
changed. The study could also help inform research looking at appetite
regulation in other animals.
Dr Dunn said:
"All species regulate their appetites to make sure the amount of food
taken in is just the right to maintain body weight and fat content. Our
research has shown that there is genetic variation in the interpretation
of biological signals sent relating to being full. This also affects
what would be considered to be the natural body weight of chickens."
World Poultry
