Hens in feeding cage

Gene-edited hens may end cull of billions of male chicks

Israeli scientists hope gene editing will end the practice of culling male chicks in the egg-producing industry, benefitting the environment and animal welfare
12 January 2023 , Kerry Taylor-Smith

In the UK, a bill currently passing through Parliament would ease gene editing regulations, despite critics arguing that it could worsen the negative effects of industrial farming

Every year, the egg-producing industry culls roughly seven billion healthy chicks shortly after hatching simply because they’re male. Israeli scientists hope to end this practice using gene editing, a method which expedites the natural selection process and could soon be used for commercial farming in the UK.

Researchers from the Agricultural Research Organisation at the Volcani Institute developed gene-edited hens that lay eggs from which only female chicks hatch. Female chicks contain W and Z chromosomes (WZ); males contain two Z chromosomes (ZZ). Researchers used CRISPR, a tool like a pair of genetic scissors that removes specific sections of DNA, to create a female with a gene-edited Z chromosome (WZ*).

The Z* chromosome prevents male embryos from developing when blue light is shone on this female’s fertilised eggs. Female embryos are unaffected and develop normally.

"The revolutionary technology is the only viable solution to stop the culling of billions of day-old male chicks,” explained Dr Yuval Cinnamon, Principal Investigator, and CSO at Huminn Poultry Company, a spin-out launched to license the technology. “Since it’s not based on sorting, it’s 100% accurate, applicable to any chicken breed, and designed to seamlessly integrate with farming.”

Cinnamon says the technology offers substantial savings to hatchers and benefits the environment: “As the layers and table eggs that they lay are identical to ones currently used by the industry, they can be marketed without further regulation.”

Compassion in World Farming, a UK-based animal welfare organisation that collaborated on the work, says the breakthrough represents an important development for animal welfare. The next step is to see if the hens and their offspring lay eggs suitable for human consumption and proceed through the commercial lifecycle without any unexpected welfare issues.

Gene editing, or precision breeding, is considered less controversial than genetic modification: instead of inserting genes (sometimes from other species), targeted genes are removed to create an organism with desirable genetic traits, e.g., crops or animals resistant to pests or illnesses like bird flu, on shorter timescales than through traditional breeding or natural processes. 

Gene editing is not currently permitted in the UK, however the Genetic Technology (Precision Breeding) Bill would ease regulations, allowing its use in commercial farming

Gene editing is not currently permitted in the UK, however the Genetic Technology (Precision Breeding) Bill passing through Parliament would ease regulations, allowing its use in commercial farming where genetic changes might occur naturally or through traditional breeding methods.

Defra state the Bill will enable the use of such technologies to boost food production and support farmers to grow more productive, healthier and resilient crops, paving the way for Britain to become the best place in the world to invest in agri-food research and innovation.

But critics argue gene editing could worsen the negative effects of industrial farming. Jo Lewis, Soil Association Policy Director said the Bill suggests the government are “casting about for silver bullets” and prioritising unpopular technologies rather than focusing on real issues, such as lack of crop diversity, farm animal overcrowding, and decline in beneficial insects who eliminate pests.

“It avoids dealing head-on with the transformation needed in our food and farming system for true security and resilience,” Lewis added. “Instead of trying to change the DNA of highly stressed animals and monoculture crops to make them temporarily immune to disease, we should be investing in solutions that deal with the cause of disease and pests in the first place.”


Image credit: Shutterstock

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