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Even the most clueless consumer likely suspects that all is not well on the big factory farms that raise animals for food, but let me share the details of one practice with which you might be unfamiliar: Every hour, across the world, around 742,000 freshly hatched male chicks are born. A few hours later, they’re tossed into a grinder, which kills them instantly, or gassed with carbon dioxide, which knocks them unconscious before killing them. (Rarer methods include burning, electrocution, suffocation, and drowning).
While the female chicks go on to lay the more than 1.2 trillion eggs humans consume annually, 6.5 billion male chicks each year are hatched, only to be quickly snuffed out. That’s because they don’t lay eggs, so they’re of no use to the egg industry, and because they don’t grow as big and fast as other chicken breeds, they’re of no use to the chicken meat industry. Even though culling costs egg producers an estimated $500 million a year, it makes more economic sense to just kill the males on day one, rather than spend an additional dollar raising them.
Undercover investigations into hatcheries have drawn some public attention to male chick culling, enough that in recent years a number of European countries, including Germany and France, have gone so far as to ban the practice, giving hatcheries and egg producers a few options: raise male chicks for meat (albeit inefficiently), raise “dual-purpose” breeds (ones that lay a relatively moderate number of eggs and grow to a moderate size), import hens from neighboring countries, or shut down operations.
But there’s another option: They can use emerging technology to identify the sex of the chick while still in the egg so they can destroy it before it hatches, before the chick can feel pain.
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That last possibility has gained momentum in recent years. Since 2019, five companies have managed to commercialize in-ovo — meaning in egg — sexing technology that enables them to identify the sex of the chick around either day nine or day 12/13 from when the egg incubation starts, depending on the approach. Such advances have already saved tens of millions of male chicks from being born, only to be swiftly culled. It’s estimated that 10 to 20 percent of Europe’s hen flock now comes from cull-free hatcheries.
But there’s a catch: Scientists believe that chick embryos could potentially feel pain as early as day seven of their 21-day incubation period. That means that even with the most advanced in-ovo sexing, male chick embryos could still be experiencing suffering.
A new preprint study, funded by the German government and conducted by researchers at the Technical University of Munich, provides some evidence that chicken embryos may not be capable of feeling pain until much later in the incubation period, after day 12.
Researchers applied potentially painful stimuli like heat and electricity to chicken embryos from day 7 to day 19 of their 21-day incubation, measuring their heart rate, blood pressure, brain activity, and movement, all in an effort to uncover whether the stimuli translated to experienced pain. Brain activity only began on day 13, movement from beak stimulation increased significantly on day 15, blood pressure increased significantly on day 16, heart rate jumped on day 17, and body movement increased significantly on day 18.
The findings arrive at a critical juncture for the effort to end the annual shredding and gassing of 6.5 billion male chicks. Beginning in 2022, Germany required hatcheries to destroy male chick embryos prior to hatching, and starting in 2024, German hatcheries must destroy eggs containing male embryos before day seven of incubation. That would require in-ovo sexing technology that works earlier than any company has yet been able to commercialize.
As a result of the new study, however, Germany’s Ministry of Food and Agriculture has suggested the government will instead require hatcheries to destroy eggs before day 13, which means the companies that cull at days 9 and 12 are in the clear (France’s ban on chick culling, which went into effect in January of this year, starts on day 15).
The study also provides clarity to policymakers elsewhere — Italy’s ban goes into effect in 2026 but doesn’t yet stipulate a cull-day threshold, while the European Commission is expected to eventually ban the practice continent-wide.
But the German study may not be the final word. Future research could determine the pain threshold to be sooner or later than day 13.
“We have to see whether this will become the new consensus or whether more confirmatory research has to be performed,” said Matthias Corion and Simão Santos, leading in-ovo sexing researchers at the MeBioS division from the Department of Biosystems at the University of Leuven in Belgium, over email to Vox.
Animal advocates are cautiously optimistic. “I think that we need to be very flexible,” said Sharon Nuñez Gough, president of Animal Equality, an animal rights group that has campaigned in Europe to end male chick culling. “I think if [German policymakers] move it up to day 13 it’s wonderful ... but there could be studies that come out in a couple of years that say no, it’s actually day 11 or it’s actually day 10.”
Jörg Hurlin, managing director of in-ovo sexing company Agri-AT noted over email to Vox that the study leaves the door open to pain perception beginning even later: “[T]he scientists only say that from the 12th day of incubation, a pain sensation can no longer be excluded, but they do not prove it either.”
Despite the scientific and political tailwinds behind efforts to phase out male chick culling, they face strong headwinds with the global egg industry under pressure to take on other costly issues, like converting barns to cage-free and bringing record prices down amid high inflation and a deadly bird flu outbreak that has resulted in the death of tens of millions of hens.
Those challenges aside, ending the culling of 6.5 billion male chicks is a critical and doable low-hanging win for animal welfare — if the technology can further advance.
There’s more than one way to sex an egg
One thing the in-ovo sexing field has going for it is that there are so many ways to identify the sex of chickens before they hatch, which is why some 13 companies and academic teams have sprung up over the last decade to turn their theories into workable technology.
Some companies employ noninvasive imaging to look inside the egg, which is what Agri-AT uses in its Cheggy machine, scanning 20,000 eggs per hour at nine hatcheries across Europe. It’s fast and low-cost, but it only works for brown eggs, and it identifies the sex on day 13 — meaning the embryos could feel pain — though it can stun them prior to killing them, rendering them insensitive. It can also work on day 12, though it’s less accurate. The company is currently trialing a new approach with researchers at the Technical University of Dresden to identify the sex as early as between day four to day six of incubation.
Orbem, another company that uses noninvasive imaging, has deployed its technology — which works on day 12 and for both white and brown eggs — in two French hatcheries.
Another approach is allantoic sampling, which entails making a tiny hole in the egg and extracting fluid for rapid analysis, not unlike the amniocentesis tests used on pregnant people. It’s nearly 100 percent effective as of around day eight or nine of incubation, though it’s slower and costlier than the imaging technology. Three companies in Europe have commercialized this approach and grocery shoppers in Germany, Switzerland, the Netherlands, and elsewhere in Europe can find both eggs and egg-based products under the Respeggt brand that come from supply chains free of male chick culling, with an additional cost of around one to three Euro cents per egg or more. (Aldi, one of the largest grocers in Europe and Germany, has pledged to phase out male chick culling from its egg supply in Germany, but declined to answer questions about the status of its progress.)
And there are other approaches in the innovation pipeline. Late last year, an Israeli research center successfully gene-edited DNA into chickens so that when their eggs are exposed to blue light, the DNA is activated and the development of male embryos stops. Gene editing is potentially much cheaper and faster (once the technology is fully developed) than the other approaches, but it likely faces steep political hurdles: Many European countries have slow regulatory processes for genetically edited food, and the same consumers who might be willing to pay extra for cull-free eggs could balk at a gene-editing process. It’s worth noting, however, that the eggs consumers eat won’t be genetically altered — female embryos are genetically left untouched.
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“Farmers will get the same chicks they get today and consumers will get exactly the same eggs they get today,” one of the Israeli researchers told the BBC.
The promising if shaky start to the end of male chick culling
Despite the burst of innovation, experts say no single approach has yet met all six criteria hatcheries require to scale up: the ability to process a high volume of eggs (20,000 to 30,000) per hour, effective for both white and brown eggs, 98 percent or higher accuracy, low cost, sex identification early in the incubation period, and high hatchability rates. That has kept the egg industry from fully adopting any of them, and while regulation is coming down the pike (or already in place), lack of clarity about which day of incubation will be the cut-off further complicates matters.
“There is always a trade-off somewhere,” said Corion and Santos over email. “Hatcheries are reluctant to adopt a technology right away because these technologies are still in development and when they invest, they want it to hold for years.”
Robert Yaman of Innovate Animal Ag, a new organization based in the US that aims to speed up the development of animal welfare technology, said that while in-ovo sexing isn’t where it needs to be, it will get there.
“With any sort of industrial agricultural technology, it just takes time to roll out,” Yaman said. “Once the technology is ready, you’re not going to see it in every country around the world the next day. It’s going to take time to manufacture the equipment, to work on those commercial partnerships. And so I think if you look at the rate of progress and speed of uptake, it’s actually going very well.”
While it’s impressive that an estimated 10 to 20 percent of Europe’s hen flock now comes from cull-free hatcheries, a shift that occurred from 2019 to 2023, there have been some unexpected consequences to Germany and France’s laws.
Public policy often lags behind technological change, but the case of male chick culling is the opposite: Germany banned the practice in 2019 (the ban went into effect in 2022) when the technology was just starting to go online in European egg hatcheries. While the technology has been adopted relatively quickly, and policymakers have moved uncharacteristically fast on the issue, many egg companies are holding out until the technology develops further — and have found loopholes around the law in the meantime.
According to the German magazine Der Spiegel, many male chicks hatched in Germany were raised for meat, and at least 300,000 male chicks have been hatched and transported to other countries to be raised for meat, including Poland, where animal welfare standards are weaker. Many German egg producers are importing egg-laying hens from the Netherlands to stock their farms.
France’s ban went into effect at the start of 2023, but egg producers received permission to continue culling male chicks from white chicken eggs as complying with the ban required the allantoic sampling approach, which is costlier. (Most eggs in France are brown; white eggs account for just a little over 10 percent of the egg supply — however, the company Orbem, which just launched, can sex both brown and white eggs). One animal rights group called the carve-out a “betrayal.”
The US, by contrast, has moved far slower on the issue, with the only significant contribution coming from the Foundation for Food & Agriculture Research — an organization that collaborates with industry and academia — and its Egg-Tech Prize, which is offering up to $6 million in prizes to in-ovo sexing researchers and startups. Open Philanthropy, a foundation that funds animal welfare initiatives, contributed up to $3 million to the contest.
In 2016, the United Egg Producers (UEP) — the US egg industry’s main trade group — called for the elimination of male chick culling by 2020, but in 2021 said, “[A] method that meets the food safety, ethical standards and scalable solutions needed for the United States is not yet available.” UEP declined responding to questions, but did recently tell Ag Funder News that nothing had changed since its 2021 statement. This means that American consumers, unlike their European counterparts, have no real way to buy eggs free of the taint of culling.
However, USPoultry — an organization representing egg and poultry trade groups, including UEP — donated toward the Egg-Tech Prize in 2020.
“You tend to think of the US as an innovation leader and technological leader but I think this is one area where we’re kind of falling behind,” Yaman said.
Carmen Uphoff, COO of Respeggt, said the company hopes to expand into the US soon and help pioneer a new higher-welfare egg category, like organic or cage-free.
“Hatcheries don’t like to do chick culling, it’s just they didn’t have any other solutions until now,” she said, later adding, “The technology is actually there and could be ordered ... the market is ready.”
As is the case with so many other animal welfare issues, the US is lagging years behind Europe. If that holds true on the matter of ending the brutal culling of billions of male chicks, America’s egg supply probably won’t have cull-free eggs anytime soon. But if the technological and political progress continues at the pace it has, it could only be a matter of time until in-ovo sexing isn’t just the more ethical choice for US egg producers, but also the more economical one.
Correction, May 4, 3:30 pm: A previous version of this article misstated the number of hatcheries in which the company Orbem operates.
