New Breakthrough Could Avoid Culling Of Millions Of Live Chicks

Shell-sniffing technology can determine the chicks' sex before hatching, avoiding the need for live culling.


Tom Hale

Tom is a writer in London with a Master's degree in Journalism whose editorial work covers anything from health and the environment to technology and archaeology.

Senior Journalist

A group of baby yellow chicks in a basket.

They may be cute, but male chicks are useless in the eyes of industrialized egg farming.

Image credit: Mai.Chayakorn/

New research has found a method that can determine the sex of a chicken in early development by “sniffing” the scent emitted through the shell. If the technology is successfully scaled up, it has the potential to avoid the culling of millions of live chicks.

Over 350 million male chicks are culled each year in the US. Since male chickens do not lay eggs and can’t be fattened up quickly enough to be sold for meat, farmers only require a few to fertilize eggs, leaving the majority to be considered useless for industrialized egg production. 


Just hours after chicken eggs hatch, workers separate the males from the females, after which the males are put aside to be slaughtered. This typically involves gassing them with CO2 or simply chucking them into a shredder.

To avoid mass-culling of newborn birds, technologies have been developed that can sex the chicken before they hatch, either by sampling the inside of the egg through a tiny hole in the shell or imaging through the shell.

Scientists at the University of California, Davis and SensIT Ventures, Inc have recently looked to find a new way to determine the sex of a chick egg as early as possible without opening it. 

Their novel method involves sticking a suction cup on the shell to pick up on volatile organic chemicals emitted by the embryo. They then determined the sex of the unborn chick by using chemical analysis techniques, such as gas chromatography/mass spectrometry.


They concluded that this method was able to correctly identify male and female embryos at eight days of incubation with 80 percent accuracy, based on two minutes of sampling.

A key feature of the new method is that it could, in theory, be integrated into the current industrial process without too much hassle. The patented technology has been licensed by SensIT, which aims to commercialize the method. 

Some countries, most notably Germany, have recently decided to ban the mass slaughter of male chicks. Following Germany's lead, the French government announced a similar ban, although animal rights groups believe it features some glaring loopholes. 

For now, male chick culling remains an inevitable part of industrialized egg production. However, research has shown that the public is often unaware of the current practice of killing male chicks and is shocked to hear about the grisly process. Furthermore, they do appear to support alternatives to culling, such as early sex determination of eggs. 


With new technologies like this, the hope is that live culling of chicks could become a thing of the past. 

The study is published in the journal PLOS ONE.


  • tag
  • animals,

  • agriculture,

  • culling,

  • volatile organic compounds,

  • farming,

  • food,

  • egg,

  • chick culling,

  • chicken eggs