Every year, billions of male chickens are killed in hatcheries around the world. But a new imaging technique may be changing these culling practices by making it possible to determine the sex of chicks before they hatch.
In the poultry industry, male chickens are of little economic value. They don’t lay eggs and they are not suitable for meat production. Because of this, day-old male chicks are culled, typically by asphyxiation or grinding.
To find an alternative to this unfortunate practice, a team of researchers working in Germany investigated whether in-egg optical spectroscopic techniques could be used to determine the sex of developing chickens.
Creating a small window in the egg’s shell, the researchers used a near-infrared laser to illuminate blood vessels outside the embryo and analyzed fluorescence signals obtained directly from the blood cells.
They found that the blood of male embryos had a characteristic fluorescence band located at approximately 910 nm and visible within four days of the egg being laid. These light signals, therefore, provide a unique sex-specific fingerprint, allowing males and females to be differentiated early in their development. When tested, the spectroscopy method correctly predicted the sex of developing embryos with a 93% accuracy rate.
Not only is this fluorescence technique quick and accurate, but it requires no tissue or fluid extraction, making it non-invasive and non-destructive.
Optical methods such as this can provide inexpensive, real-time sexing of eggs without the need for chemical or genetic testing. The hope is that this method can be adapted into a large-scale, industrial-sized system for efficient (and early) detection of male embryos. If adopted by the poultry industry, this in-egg sexing technique could put an end to current, ethically-problematic culling practices.