The Roslin Institute
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About Cute Egg

Providing a safe supply of eggs to hatch the next generation of chickens

Every year the poultry industry supplies huge numbers of chicks that grow into egg-laying and meat-producing chickens. This is possible because eggs can be artificially incubated and hatched. This allows breeding hens to produce many more eggs and chicks, as they do not need to spend time incubating their eggs themselves. Artificial incubation also reduces the risk of disease being passed from mother to chick, as the different generations of chickens are separated from each other.

However, diseases can still be transmitted between generations of chickens, especially during egg collection and transportation. Eggs can become infected with microorganisms that can harm their contents, which is dangerous for food safety, animal and human health. Reducing the risk of transmission will help maintain biosecurity for chicken breeding and make eggs even safer for consumers.

Egg diagram

The Cuticle

The egg cuticle is a protein layer that covers the surface of the egg and fills the pores that allow air inside for the growing chick. The cuticle prevents bacteria from entering the egg and forms its first line of defence against infection. Bacteria can be transmitted to the egg from its mother during laying, or from contact with the environment – from collecting belts or handling equipment.

Protection Against Disease

Not all eggs have cuticles of the same quality – natural variation between hens means that some cuticles are better at protecting the egg from bacteria than others. Studies show that eggs with good quality cuticles are less likely to be infected by the bacteria E. coli than eggs with poor quality cuticles. Selecting for better cuticle quality in eggs will reduce the risk of contamination by E. coli and other harmful microorganisms.

Our Research

We have developed ways to measure the amount of cuticle that each hen deposits on its eggs. We know that cuticle quality varies due to differences in the genetics or "DNA blueprint" of each hen, so if we select chickens that lay eggs with high quality cuticles we can breed them to produce eggs with better protection against bacteria.

We have learned a lot more about how the cuticle is formed and deposited on the egg as soon as it is laid. We have also investigated how environmental factors, stress, hormones, the age of the hen and the age of the egg can affect cuticle quality.

Selective breeding diagram
Egg tray photo

How Do We Measure Cuticle Quality?

Working with chemists from the University of Edinburgh, we have developed techniques that measure cuticle quality using light.

White light is made up of a spectrum of colours that materials can absorb and reflect from different wavelengths. Using a machine called a spectrophotometer, we can measure the amount of white light reflected by eggs' cuticles. The amount of light reflected at a given wavelength from different eggs can be compared to measure the amount of cuticle and its quality.

We use other techniques that involve fluorescent and infrared light to tell us more about the chemical structures of the cuticle and its role as a physical and chemical barrier.

Some of our methods involve staining the eggs to reveal more about their cuticle (similar to the Cute Egg: Staining activity in our Cute Egg kit!) and we are also investigating the many different proteins that make up the cuticle.