Gene-edited livestock could boost food production in growing world

Scientists have created pigs, goats and cattle that can serve as viable “surrogate sires”, male animals that produce sperm carrying only the 
genetic traits of donor animals.

Researchers say the development could speed up the spread of desirable characteristics in livestock and improve food production for a growing global population.

Additionally, it would give breeders in remote regions better access to genetic material of elite animals from other parts of the world.

It would allow more precision breeding in animals such as goats where using artificial insemination is difficult.

Scientists used the gene editing tool CRISPR-Cas9, to knock out a gene specific to male fertility in the animal embryos that would be raised to become surrogate 
sires.

Although the male animals were born sterile, they began producing sperm after researchers transplanted stem cells from donor animals into their testes.

The sperm the surrogate sires produced only carried the genetic material of the selected donor animals.

The gene-editing process employed in the study published in the Proceedings of the National Academy of Sciences journal seeks to bring about changes within an 
animal species that could occur naturally, such as infertility.

The study is the result of six years of collaborative work among researchers at WSU, Utah State University, University of Maryland and the Roslin Institute at the University of Edinburgh.

The researchers used CRISPR-Cas9 to produce mice, pigs, goats and cattle that lacked a gene called NANOS2 which is specific to male fertility.

The male animals grew up sterile but otherwise healthy.

After they received transplanted sperm-producing stem cells from other animals, they started producing sperm derived from the donor’s cells.

The surrogate sires were confirmed to have active donor sperm.

In the study the surrogate mice fathered healthy offspring who carried the genes of the donor mice.

However, the larger animals have not been bred yet, and Prof Oatley’s lab is refining the stem cell transplantation process before taking that next step.

Researchers say the technology has the potential to help food supply in the developing world, where herders still have to rely on selective breeding to improve their stock.

Professor Bruce Whitelaw of the Roslin Institute said the study provides a powerful proof of concept.

He added: “This shows the world that this technology is real. It can be used.

“We now have to go in and work out how best to use it productively to help feed our growing population.”