Scientists have discovered an unusual property of chicken eggs that could eventually help solve one of the poultry industry’s biggest ethical problems.
By shining light into intact eggs, researchers found that they may be able to reveal what is happening inside without cracking the shell open.
The study, published in Newton, suggests that this technique could one day determine the sex of developing embryos, identify fertilized eggs and assess egg quality.
If successful, it could help reduce the practice of killing male chicks shortly after they hatch.
In the egg industry, male chicks are considered economically unprofitable because they cannot lay eggs and do not grow quickly enough to be used for meat production.
As a result, more than 300 million male chicks are culled every year in European hatcheries alone.
The practice has been heavily criticized by animal welfare groups, and several countries are seeking ways to end it.
The new research focuses on how light behaves inside a chicken egg. Scientists discovered that when light enters an unbroken eggshell, it does not simply pass through and leave. Instead, the shell traps the light, causing it to bounce around repeatedly inside the egg.
The researchers found that tiny particles of light, called photons, can travel a total distance of up to two meters inside a chicken egg. This is remarkable because a chicken egg is only about four centimeters long. In other words, the photons travel a path that is about 50 times longer than the egg itself.
The team studied how visible and near-infrared light moved through whole eggs before incubation and during the first eight days of embryo development. They described the eggshell as an “integrating sphere,” meaning it acts like a tiny chamber that efficiently traps and scatters light.
The researchers were surprised by how effective the eggshell is at keeping photons inside. According to the scientists, such long light paths are rarely seen in natural materials.
This discovery could have important practical applications. Because light interacts with the structures inside the egg, scientists may eventually be able to gather information about the embryo’s development without touching or opening the shell. By carefully analyzing the returning light, it may become possible to determine whether an egg is fertilized, monitor embryo growth and even identify the embryo’s sex.
The technology belongs to a field known as optical spectroscopy, which uses light to reveal the physical and chemical properties of materials. Similar techniques are already used in medicine to examine tissues and monitor organs and in agriculture to study fruits and plants.
However, the researchers emphasize that much more work is needed. The optical behavior of eggs is complex and not yet fully understood. Future studies will investigate how light patterns change as embryos continue to develop and how different parts of the egg contribute to these effects.
The scientists also suggest that the egg’s unusual ability to scatter light may have evolved to protect developing embryos from harmful ultraviolet radiation and help maintain temperature when parent birds leave the nest.
Although the technology is still in its early stages, this simple act of shining light into an egg could one day lead to more humane and sustainable poultry farming practices.
