Fast track – or road to ruin?

Science offers a way to bring about dramatic improvements in livestock – including salmon – but not everyone is happy about it, Robert Outram finds.

Gene editing is a divisive and, some would say, scary concept, but fear not. The UK Government has rebranded it as “precision breeding”. While this may reassure some people, it is unlikely to put the debate about it to bed.

Technology such as CRISPR has made it possible to understand and manipulate genetics in ways that would once have been dismissed as science fiction. Desired genes can be added to the mix and those with a harmful effect can be removed.

It is important, however, to understand the different categories within the technology. Genetic modification (GM) can include the insertion of genes from a completely different species to achieve the desired effect, whether that is a drought-resistant strain of corn or a faster growing chicken.

In contrast, gene editing (GE) is limited to genes that would naturally occur within a given species. It could mean, for example either removing a gene associated with a hereditary defect, or ensuring that genes linked to specific disease resistance, or growth, are spread more widely.

To some extent gene editing replicates what can be achieved by selective breeding, but in a way that takes many fewer generations to achieve – hence the term “precision breeding.”

GM is not permitted on a commercial basis in many jurisdictions, including the UK and European Union, and up until now that has included gene editing. The EU shows no signs of changing its stance in a hurry, but in England the Precision Breeding Act came into force in March last year. This legislation opens the door to gene editing at a commercial scale for plants and, potentially, animals.

Dr Janet Talling, Defra

This, some argue, could be a game-changer for aquaculture. At Aqua UK in Aviemore this May, Dr Janet Talling, Head of Genetic Technology and Farm Tenancy Policy in the Innovation, Productivity and Science Division, Defra (the Department for Environment, Food and Rural Affairs) explained what it could mean.

Defra has already drafted regulations to cover PBOs (precision bred organisms) for plants only, she said. Statutory instruments were expected to be laid in summer 2024 – although this was before the general election was announced.

In England, this legislation does not appear to be a party political issue. Vet Record, the news publication of the British Veterinary Association, has reported that, in opposition, Labour offered a cautious welcome to the plans, albeit with a few caveats such as the need for tighter and more transparent regulation.

As of now, the Food Standards Agency is developing a new authorisation framework to regulate the use of precision-bred organisms in food and feed products in England.

This framework will consider any risk these organisms pose on a case-by-case basis and will ensure that all associated food safety risks are proportionately assessed, managed and communicated to ministers to inform their decision on whether the organism is safe to be marketed for use in food and feed.

In England, commercial PB will start with plants

Defra is also now starting consultation on potential animal welfare issues around PBO and has established a Precision Breeding Working Group. The department would need to grant a market authorisation for any PB animals to be marketed in the UK.

When applying, the company concerned would need to confirm that the health and welfare of the animal concerned, and its progeny, are not expected to be adversely affected by any trait resulting from precision breeding.

Each application would be reviewed by the government’s Welfare Advisory Body, which would report to the Secretary of State, who would then in turn decide whether to grant the authorisation.

Even if granted, there may be post-market monitoring requirements to identify any health and welfare problems that might emerge.

The animal welfare framework also involves the Home Office, which sets rules for animal experimentation.

Meanwhile for plants, legislation will be amended to ensure that PB varieties can be registered. Talling said research is measuring the impact of PB traits, taking a holistic assessment.

Public consultation is due to take place on PB for animals through 2025. The aim is to bring out draft legislation the following year and companies will be invited to make applications to start using PB commercially.

Gene editing in the lab

Resistance in Scotland
The position taken by the Scottish Government is very different, however. Agriculture is a devolved policy area and the SNP administration in Scotland has made it clear that it will continue to treat PB organisms as GM – which means they could not be produced commercially.

The legislation covering the UK single market means, however, that while the Scottish Parliament could prevent the production of PBOs in its own jurisdiction, it could not stop PBOs produced in England being sold in Scotland – potentially putting Scottish farmers at a disadvantage.

The devolved administration in Wales is still considering its position on the issue.

Meanwhile, gene editing is already permitted throughout the UK for research purposes. SRUC (Scotland’s Rural College) has a project underway to understand d the implications of precision breeding for animals, focusing mainly on the three species most likely to be candidates for the new approach: pigs, poultry and Atlantic salmon.

The aim is to set out “…a welfare assessment framework that will allow the effects of precision breeding technologies on welfare to be assessed on a general and edit-specific basis”.

Alejandro Gutierrez, CAT

Also speaking at Aviemore, Alejandro Gutierrez, Director of Genetic Services UK at CAT, the Centre for Aquaculture Technologies (CAT) who is based in Stirling, argued that gene editing will mean a “step change in the rate of genetic improvement”. This has already been shown in for example Argentina, where PB is not being treated as the same as GMO. Significant advances in yield, growth and feed conversion rate were seen in PB tilapia.

In Japan, PB has also been used with red sea bream.

But Gutierrez also warned that some precautions are essential when raising gene-edited fish, above all to ensure that they cannot have the opportunity to interbreed with the wild population. These include sterility – which he called “a fundamental requirement” – and effective biocontainment.

In fact, he said, there is a paradox: “Farmers want fertile animals but need sterile animals.”

Fortunately there is a solution, he added, in three steps:
1. develop desirable GE strains, and breed high-performance individuals that are sterile, with inactive gonads but viable germ cells;
2. extract germ cells and transfer to sterile GE surrogate broodstock with active gonads but no germ cells; and
3. breed surrogate broodstock to produce many sterile offspring.

Gutierrez stressed: “We need to educate the public to explain that no new DNA will enter the animals.”

CAT’s research suggests that, for Atlantic salmon, GE could mean a 15% increase in growth rates and a 7% improvement in feed conversion ratio among other benefits. He said that, worldwide, the sector could see an increase in value of $1.8bn (£1.4bn).

Ross Houston, Benchmark Genetics

For and against
Ross Houston, Director, Genetics and Innovation with Benchmark Genetics, is also an advocate of the technology. He says: “Gene editing presents a major opportunity for aquaculture by improving animal performance, health, and welfare in a sustainable manner.

“The majority of ongoing research and development initiatives in this area focus on the trait of disease resistance, for which gene editing presents an opportunity to develop fully resistant animals. Prevention of disease is a better approach than treatment, and layering genetic resistance into the DNA or eggs is the ultimate in disease prevention. As such, there is transformative potential to address some of aquaculture’s biggest health, welfare, sustainability, and social licence issues. For example, major projects are targeting resistance to sea lice in Atlantic salmon, and considering the impact that a full genetic resistance could have in terms of avoiding the need for physical or chemical treatments, handling of the fish, and associated licence to operate.

“Gene editing technology is potentially of major benefit to aquaculture breeders, but the main benefit would be to the industry in general.”

He adds, however: “Gene editing is not in any way a replacement for selective breeding programmes, which focus on cumulative and permanent improvement of many beneficial traits, while preserving genetic diversity. This practice, enabled by innovations in technologies related to genomics, high-throughput phenotyping, and cryopreservation will continue to be the backbone of genetic improvement and seed supply. Rather, gene editing technology will need to be integrated with such a programme to give significant added value.”

Dr Matias Medina, Aquagen

Dr Matias Medina, Aquagen’s director of R&D, based in Norway, says: “Allowing the use of gene-edited animals in a regulated way will benefit all farm production and will contribute with the development of a sustainable food system. Targeted gene editing will improve efficiency and welfare of the animals being produced.

“This would be the case for aquaculture too, where gene editing could potentially contribute with the solution of environmental, welfare and health-related challenges. Specifically, breeding and egg producing companies will benefit from gene editing by taking advantage of existing beneficial variation within the species being farmed as well as by increasing the pace of genetic changes, while keeping a balanced selection.”

Marie Smedley, Xelect

Marie Smedley, Head of Breeding Programmes with Xelect, based in St Andrews, Scotland, says: “Gene editing has potential for huge benefits to the animal breeding industry and key technology from advanced terrestrial breeding can be readily transferred to the aquaculture sector.

“Xelect is part of the Genus group, world leaders in developing and commercialising gene editing as demonstrated by the recent successes of PRRS (Porcine reproductive and respiratory syndrome) resistant edits in porcine. PRRS costs the pork industry an estimated U$2.7bn [£2.13bn] annually, highlighting the significant benefits in this sector. It is hard not to be supportive of something that has the potential for such high impact commercially, environmentally and on welfare.”

Not everyone is so supportive, however, and a number of animal welfare organisations are concerned regarding the potential downsides of gene editing.

Penny Hawkins, RSPCA

Penny Hawkins, Head of the RSPCA’s Animals in Science department, says: “The RSPCA believes that serious conflicts can arise between animal welfare and human interests. In our view, gene editing to increase animal productivity is unacceptable, because many farmed animals are already at their physiological limits, and around 12 % of animal protein produced globally is wasted every year.

“The UK Genetic Technology (Precision Breeding) Act 2023 will include secondary legislation that is intended to minimise risks to animal welfare, but this is yet to be drafted and there is no framework at all within the Act for ethical decision-making around the purposes for each gene edit. This is of concern to the public as well as the RSPCA.”

While she can see some benefit in developing greater resistance to disease in livestock, she stresses that GE should be a last resort and not a substitute for adequate veterinary care and surveillance.

Also, Hawkins says: “Using gene editing to modify animals so that they can better tolerate environments that do not meet their welfare needs, or poor husbandry, should be unthinkable and should never be permitted.”

Gene editing, subject to regulation, is already entering the commercial sphere in countries like the USA, China, Australia, Brazil and Japan. While the UK is taking a cautious approach, it looks as if we will see it in some form in England – and this will create a dilemma for the other devolved nations.