At Catholic University in the Belgian city of Leuven, a team of researchers added an additional twist with an egg-gender test that doesn’t involve extracting fluid. “Male and female chickens’ feathers have different colors, so we’ve developed a technology using special light rays that illuminate the eggs and shows which ones are male and female,” reports team leader Dr. Bart De Ketelaere. “After nine days incubation, we can determine the gender of the egg with 95 percent accuracy. After 11 days, the accuracy is 99 percent.” The catch? “It only works for brown eggs. Our technology is ready to go on the market if we find hatcheries that are fine with just gender-testing brown eggs."

Here’s another catch: A gene-testing machine costs money, and hatcheries are unlikely to buy one simply to prevent chicks’ suffering. But consumer-products giant Unilever, which owns major brands such as Ben & Jerry’s ice cream and Hellman’s mayo and buys some 350 million eggs each year, took a first step last year, announcing that it will push its egg suppliers to stop male chick culling. “Eggs are a vital ingredient used in many of our products, ranging from mayonnaises to dressings, sauces and ice cream,” says a representative for the company. “We’re working with egg producers and the wider industry, the animal-welfare community and R&D companies to find tangible ways to address this important issue.”

Yet no other major buyer or producer of eggs has taken similar action. And in the absence of consumer boycotts of eggs produced on the backs of dead male chicks, why would they? But the in ovo sexing pioneers have a trump card: In the long run, the technology saves money. With the male eggs removed from incubation machines 12 days earlier, heating the remaining half requires much less energy.

Gender-selected eggs are not the only innovative solution the industry is pursuing. Last year Lohmann Animal Breeding, the German-based world leader in chicken genetics, which is also experimenting with egg-gender testing, presented its “dual-purpose chicken,” the result of five years of genetic experimentation. The Lohmann Dual lays 250 eggs per year and reaches a respectable 5-pound slaughter weight in 56 days. (Current broiler chickens reach a slaughter weight of 7 pounds.) A male chick born as a Lohmann Dual would, in other words, face the more promising prospect of growing up a broiler, much like the Blocks’ male chicks.

In Switzerland, meanwhile, the supermarket chain Coop and two leading farms have launched a pilot project to develop their own dual-use chicken. Compassion in World Farming, for its part, advocates resurrecting the Beijing-You, an almost-extinct Chinese chicken breed that excels both at egg laying and growing a large, broilerlike body. “The result is the same. The chicken will die,” says Gonzalez Fischer. “But at least it won’t have lived for nothing.”

But since dual-purpose chickens eat more and lay fewer eggs, their meat and eggs are be more expensive. The obvious question is whether consumers will buy expensive eggs and meat that don’t involve the killing of male chicks or close their eyes and go for the cheap version. And there’s more experimentation underway, with researchers exploring a genetic-modification technology that changes the gender of eggs as well as one in which male eggs take on a slightly different color.

But such futuristic engineering may prove too off-putting to consumers who eventually have to eat the eggs and meat. Researchers are already trying to up the egg-amniocentesis ante by creating a gender test that could be used on two- to three-day-old eggs, allowing the male eggs to be used as ordinary eggs. Eggs sexed at nine days can’t be used as eggs because the chicken embryo has started developing.

Would the Blocks, who like most other hobbyist hen keepers don’t sex their eggs, now consider doing so? “In our small henhouse, it doesn’t really make sense,” says Arne Block. “In an ideal world, male chicks of the laying-hen breed should be allowed to live and become broilers, but I do realize that that’s not viable in large companies. Sorting out male eggs before they hatch seems more merciful than killing the chicks.”