Almost 13 billion eggs are consumed in the UK each year and chicken accounts for almost half the meat we eat. Contaminated eggs can cause food poisoning in people, so efforts to reduce the risk are vital.
Researchers at the Roslin Institute – www.ed.ac.uk/roslin – are investigating why some eggs are less susceptible to infections than others. The main focus of the research is to reduce the risk of disease being passed on to the chicks that hatch from these eggs. They hope their findings will help to breed chickens that lay safer eggs.
Bacteria such as E.coli are transmitted to eggs from the mother hen during laying or from contact with the environment. Experts are studying a layer of the outside of the shell called the cuticle, which protects the egg from bacteria. Some eggs have better quality cuticles than others, which are less likely to be infected by bacteria than those of poorer quality.
The team is investigating genes that are linked to cuticle quality with a view to selectively breeding chickens with beneficial genes, which may lay safer eggs. They are also investigating how environmental factors, stress, hormones, the age of the hen and the age of the egg can affect cuticle quality. Poultry producers use a range of methods to ensure the safety of the eggs and meat that reach supermarkets, including vaccinating hens and practicing good hygiene on farms.