Gene Editing

Thursday, May 22, 2025

When Does It Make Sense In Livestock Production?

By Lilian Schaer, For Livestock Research Innovation Corporation

The interest in the possibilities offered by gene editing is growing – in both human medicine and in the livestock world. In livestock production, many of the most promising examples and opportunities that have come forward so far involve the pork industry.

Gene editing can offer significant solutions to some of the big challenges in livestock production, even though the technology is still evolving, the regulatory environment is complicated, and it is still unknown how consumers will respond.

Dr. Mike Lohuis, vice president of research and innovation at Semex Alliance, believes the world will see gradual regulatory approval of gene editing projects in key markets over the next decade.

“Gene editing is a more exact and powerful form of genetic engineering than Genetically Modified Organisms (GMOs) and more likely to be accepted,” he said during a Horizon Series webinar on gene editing hosted by Livestock Research Innovation Corporation (LRIC) last year.

“We are likely to see it in high-value market scenarios where the market is big enough (for companies) to recoup their investment. It makes most sense if it is a solution to a thorny problem like disease risk, environmental protection, climate change adaption, animal welfare or food safety,” he added.

PRRS resistance

A recent high-profile example involves swine production, where researchers have developed a pig that is resistant to Porcine Reproductive Respiratory Syndrome (PRRS) virus.

PRRS is the costliest swine disease in the world, costing the North American industry hundreds of millions of dollars in losses every year.

A study at Iowa State University pegged losses by U.S. hog farmers to the virus at about $1.2 billion USD ($1.7 billion CAD) annually; in Canada, it is estimated to cost about $200 million in annual losses. And according to the Roslin Institute at the University of Edinburgh, up to 80 per cent of piglets infected with PRRS will die from the virus.

Already approved in Colombia and Brazil, the technology is currently under review in Canada, the United States, China, Japan and Mexico.

“PRRS is an animal health issue. It solves a thorny problem: Vaccines don’t work very well, so there is no traditional solution, and the size of the market is huge,” Lohuis said, adding it remains to be seen whether consumers will understand the complexity of the technology – and accept it, even though it will protect pigs from disease and suffering.

The battle for acceptance

It was activist pressure and a lack of understanding of technology that created public resistance to GMOs and led to the failures of early high-profile genetic modification breeding projects – even though they also solved so-called thorny issues.

About two decades ago, the United States Department of Agriculture developed a mastitis-resistant cow. The more high-profile example, however, involves the pork industry.

In the late 1990s, the University of Guelph bred the Enviropig, animals modified to produce manure that was more environmentally friendly because of lower phosphorus levels. Excessive phosphorus causes algae blooms in water courses, for example, which harms aquatic life.

This came at a time when pork production was expanding rapidly in Canada and the United States. The construction of many large, modern new barns caused the industry to face increased public and regulatory opposition around concerns related to odour, nutrient management and water quality.

A more environmentally friendly pig was seen by the industry as a possible solution, and Ontario Pork, along with the federal and provincial governments, provided support for the research. The U of G still has patents on the technology, but it was never commercialized.

In both instances, the animals were transgenic, meaning researchers used a gene from another species in their breeding process, creating a GMO.

The gene editing approach

Gene editing, by comparison, most often involves deleting, modifying or replacing genes that already exist in the species without introducing any new material from other species.

Different types of gene editing will generate a variety of outcomes.

In the case of the PRRS-resistant pigs, insertion/deletion (INDEL) or site-specific edits were used to shut down the receptor for the virus, so it can’t find any place on the genome to adhere to. To create hornless dairy cattle, researchers replaced the horned gene with the polled gene, and to create BVD-resistant cattle, researchers made a very specific edit to the CD46 gene.

“Gene editing is most useful for traits with no current solutions. It is progressing more slowly in animals than in crops, and technical hurdles remain. Unexpected results can occur and require significant diligence to achieve only the expected edit,” Lohuis says, adding that regulatory barriers will likely remain high for the foreseeable future.

Dr. Shayan Sharif, interim vice president of research and innovation at the U of G, believes there are two contexts where gene editing livestock makes sense: The sustainability of agriculture and its impact on the environment, and disease resistance.

Dr. Ray Lu, associate professor in molecular and cellular biology at the U of G, for example, has done some work on exploring how the technology could be used to help protect Canada’s swine herd against the threat of wild boars.

Gene editing could be used to both make the boars resistant to African swine fever, as well as slow down the speed at which they reproduce.

Sharif cautions, however, that it is also important to consider possible negative consequences of editing. Resistant animals could still become infected with a virus and shed it into the environment even though they don’t show signs of the disease.

As well, he notes, disease resistance involves a lot of different genes, and with viruses continually evolving, it will be necessary to keep pace with that evolution.

LRIC’s Horizon Series webinar with Dr. Lohuis is available at https://livestockresearch.ca/sector/gene_editing_in_livestock. BP

Livestock Research Innovation Corporation is funded in part by the Sustainable Canadian Agricultural Partnership (Sustainable CAP), a five-year, federal-provincial-territorial initiative. This article is provided by LRIC as part of its ongoing efforts to report on research, innovation, and issues affecting the Canadian livestock industry.