Chicken eggs are one of the most widely consumed animal products in the world.
However, the production of eggs involves a major ethical and economic issue: the culling of male chicks.
Every year, billions of male chicks are killed shortly after hatching because they are considered useless for egg production and meat quality.
This practice is not only cruel but also wasteful and inefficient.
To avoid this problem, researchers have been looking for ways to determine the sex of chicken embryos before they hatch, a process known as in-ovo sexing.
This would allow the selective removal of male eggs and the preservation of female eggs for hatching.
However, most of the existing methods for in-ovo sexing are either invasive, expensive, inaccurate or time-consuming.
A novel method based on volatile organic compounds
KIRILL KUDRYAVTSEV/AFP via Getty Images
A recent study published in the journal Scientific Reports proposes a novel method for in-ovo sexing based on the detection of volatile organic compounds (VOCs) emitted through the eggshell, as per Phys.org.
VOCs are small molecules that can easily evaporate and diffuse in the air.
They are produced by various biological processes and can reflect the physiological state of an organism.
The researchers hypothesized that male and female chicken embryos might produce different VOCs due to their different hormonal and metabolic profiles.
To test this idea, they collected eggs from two breeds of chickens (White Leghorn and Rhode Island Red) and incubated them for nine days.
Then, they used a device called an electronic nose to "sniff" the VOCs emitted from each egg.
The electronic nose is a sensor that can detect and analyze different VOCs based on their chemical properties.
The researchers found that the electronic nose could distinguish between male and female eggs with an accuracy of 93% for White Leghorn and 96% for Rhode Island Red.
They also identified some of the VOCs that were specific to each sex, such as hexanal, heptanal, and octanal for males, and nonanal, decanal, and undecanal for females.
These VOCs are likely derived from fatty acid metabolism, which is influenced by sex hormones.
The study demonstrated that in ovo sexing based on VOC detection is a promising technique that has several advantages over other methods, as per Popular Science.
It is non-invasive, meaning that it does not harm or interfere with embryo development.
It is also fast, cheap, and easy to perform, requiring only a simple device and a few seconds per egg.
Moreover, it can be applied at an early stage of incubation (9 days), which reduces the waste of resources and the suffering of unwanted chicks.
However, the method also has some limitations that need to be addressed before it can be implemented in large-scale egg production.
First, the method's accuracy may vary depending on the chickens' breed, age, and environmental conditions.
Therefore, more studies are needed to validate and optimize the method for different scenarios.
Second, the method may not be able to detect some rare cases of sex reversal or intersexuality in chickens, which are caused by genetic or hormonal abnormalities.
Third, the method may raise some ethical concerns about the fate of the male eggs after they are removed from incubation.
Some possible alternatives include using them for vaccine production, animal feed or biogas generation.
In conclusion, the study shows that fertilized chicken eggs can be sexed by "sniffing" volatile chemicals emitted through the shell.
This method is based on the detection of VOCs that reflect the sex-specific metabolic activity of chicken embryos.
The method is non-invasive, fast, cheap, and easy to perform, and can potentially reduce the culling of male chicks in egg production.
However, more research is needed to improve the accuracy and applicability of the method and address some ethical issues related to it.
