The mass production of chicken eggs and mostly female broilers has its downsides. Around the world, around seven billion male chicks are killed immediately after hatching every year. In Germany there are an estimated 40 million “day-old chicks” every year. In this country, they were usually no longer shredded, but killed in a carbon dioxide atmosphere by the end of 2021. The current ban on killing chicks leads – at least in this country – to the male chicks being reared until they are slaughtered or the young embryos being killed well before they hatch.
In order to distinguish male from female exmbros in the hen’s egg, a sample can be taken through the shell or, on the other hand, the egg can be X-rayed. Researchers from the University of California at Davis have now developed a potentially simpler method. They managed to sniff out the sex of the embryo inside the egg from the outside.
Hints on chick sex
The working group led by Cristina Davis, together with researchers from the start-up Sensit Ventures, focused on volatile organic substances (VOCs) that escape through the shell. Based on previous studies and their own series of tests, the scientists selected eight compounds from the large number of these VOCs that could provide information on the gender of the chicks. These include hexane, hexanal, heptanal or aldehydes such as dodecanal.
Sampling is done with suction cups used for industrial handling of eggs.
(Image: Tom Turpen, Sensit Ventures)
To determine the sex, the researchers placed a tight-fitting silicone cap on chicken eggs after eight days of incubation. In general, the incubation period for chickens is 20 to 21 days. They collected small amounts of the volatile organic substances with this cap for two minutes. They analyzed these air samples using a mass spectrometer and a gas chromatograph. The result: The sex of the chick embryos can be deduced from this gas analysis with a reliability of at least 80 percent.
Such laboratory analyzes would be too time-consuming for mass production in chicken farms. Therefore, the company Sensit is working on the development of small and inexpensive analysis chips with which the gas samples can be analyzed much faster. If air samples are taken in parallel with hundreds of silicone caps, in ovo (in the egg) sex determination could be carried out in the near future with an economically justifiable effort. The eggs with male embryos would then continue to be destroyed. But at least then no living day-old chicks would have to die a cruel death.
Mandatory and transparent labeling for the consumer as to which of the possible methods is used would be sensible. Everyone could decide for themselves whether to accept killed embryos for their egg consumption or prefer so-called “brother roosters” raised until they are ready for slaughter.
(jl)