September 16, 2013

GM animals: Why do we need them, what is in the pipeline, and what are the risks?

By Alison Van Eenennaam, Ph.D., University of California, Davis

The prospect of genetically modified food animals has been looming on the horizon for over 30 years, ever since the first genetically modified, or more correctly, “genetically engineered”, mice were produced in the 1980s. Animal breeders have been “genetically modifying” animals using traditional breeding techniques for centuries, for example, developing the Chihuahua from its wolf progenitor. Genetic engineering (GE), however, refers to the use of recombinant DNA techniques or biotechnology to intentionally modify the genome of an animal to produce a desired outcome or trait. In the case of animals, this outcome might be an agriculturally related trait like improved disease resistance or a faster rate of growth, or something related to product composition such as pork with elevated levels of omega-3 fatty acids.  There are currently no GE animals approved for food purposes.

Conversely, GE plants, which were first produced in 1983, were approved for food purposes in the 1990s and have been rapidly adopted by farmers globally. Approximately 420 million acres of GE crops (12% of total arable land) were cultivated worldwide by 17.3 million farmers in 2012. This is a 100-fold increase from the 4.2 million acres that were planted in 1996, making GE the most rapidly adopted crop technology in recent history. During the period from 1996 to 2011, the cumulative economic benefits from cost savings and added income derived from planting GE crops is estimated to have been $49.6 billion in developing countries and $48.6 billion in industrial countries[1]. A high proportion of the global soybean (81%), cotton (81%), corn (35%), and canola (30%) supplies are currently derived from GE crop varieties. Approximately 70% of processed foods available in US grocery stores contain an ingredient from a GE crop.

Animal agriculture is also highly dependent on GE crops; over 70% of harvested GE biomass is fed to food-producing animals throughout the world.  Even in the European Union (EU), where there is little cultivation of GE crops, it has been estimated that 80% of all animal feed is imported and that more than half of this is from GE crops imported from Brazil, the USA, and Argentina. The EU imports approximately 70% of the soybean meal used in animal feed and of this 80% is GE.  It has been projected that if the EU were not able to import soybean protein from outside the EU it would only be able to replace 10-20% of imports by high protein feed substitutes, and that this would result in a substantial reduction in animal protein production, exports and consumption, and a very significant increase of animal protein imports into the EU.

Despite the widespread adoption of GE crops, no GE animal has been approved for food consumption in any country. Pharmaceutical drugs produced by GE animals have received regulatory approval; however, the commercial approval of a GE food animal has yet to be accomplished. The first and currently only GE food animal up for approval, the fast-growing AquAdvantage salmon, has been undergoing regulatory review in the USA for over a decade. All regulatory studies, including food safety evaluations, were completed in 2009 at a cost of over $60 million.  In 2010 the FDA determined that the “AquAdvantage Salmon is as safe as food from conventional Atlantic salmon” and that “no significant food safety hazards or risks have been identified with respect to the phenotype of the AquAdvantage Salmon”.  Despite these findings and the proposed production of infertile triploid, all-female fish in contained inland tank systems to prevent escapement, no statement has yet been issued by the FDA regarding approval or otherwise of this first GE food animal.

Part of the reason for this protracted regulatory evaluation of the AquAdvantage salmon has been pressure from special interest groups and a handful of elected officials to prevent the product coming to market. Some activist groups have even begun actively targeting supermarket chains to boycott the GE salmon by threatening to cease purchasing at those chains unless they cede to their demands. The on-going regulatory uncertainty has had a pervasive chilling effect upon the development and commercial adoption of GE animals.  Regulatory inaction has the consequence of threatening not only the AquAdvantage salmon, but animal biotechnology in general. Although some might argue that this is a desirable outcome, it is not in society’s interest to give up on a promising set of technologies when science has consistently shown that there is nothing uniquely or inherently risky about food produced from GE animals or crops.

The risks associated with GE animals may even be less than those associated with existing production systems. For example, Atlantic salmon are commonly produced in floating ocean net-pens.  Hazards presented by conventional production include: (1) local eutrophication due to nutrient enrichment from decomposition of uneaten feed and animal wastes, (2) transmission of parasites and pathogens among cultured and wild fish populations, and (3) escapement of selectively-bred, fast-growing fertile salmon and interbreeding of cultured and wild Atlantic salmon populations.  A shift to greater aquacultural production in on-shore facilities presents an option to reduce these environmental impacts and concomitantly decrease pressure on wild-caught fisheries.

Demand for livestock products is expected to continue growing strongly through the middle of this century, and by 2050 nearly twice as much meat will be produced as today. Some of the promising applications of this technology involve the development of GE animals that are disease resistant. For example, a consortium of scientists from New York University, the International Livestock Research Institute (ILRI) in Nairobi, Kenya, the Roslin Institute and The University of Liverpool have been awarded a grant by The National Science Foundation of the USA and the Bill and Melinda Gates Foundation to develop GE cattle that are resistant to African Bovine Trypanosomiasis.

Trypanosomiasis is a disease caused by blood parasites of the genus Trypanosoma that are transmitted in Africa by tsetse flies (Glossina spp). Tsetse and trypanosomiasis threatens approximately 45-50 million head of cattle and are the major factors preventing the establishment of sustainable agricultural systems in many parts of sub-Saharan Africa. Direct losses in meat production and milk yield and the costs of programs that attempt to control trypanosomiasis are estimated to amount to up to $1.2 billion each year. If the disease did not exist, many more families could use draught animals to plough their fields rather than manual labor. All told, trypanosomiasis is estimated to cost sub-Saharan Africa $4 billion or more each year.

There are many other examples of potentially beneficial applications of GE animals including applications that improve the healthfulness of animal products, and the health and welfare of the animals themselves. These include GE animals with altered milk (e.g. decreased lactose) and meat (e.g. increase omega-3 fatty acids) composition for food purposes. Researchers at UC Davis are working on goats that produce milk which is protective against juvenile diarrhea, a major killer of infants in developing countries. Other researchers are working to develop GE animals that produce single-sex offspring in species where only one gender produces the food product, such as eggs or milk. Yet another group is working to edit the DNA sequence of a single gene in the bovine genome of horned cattle breeds to render them naturally hornless or polled, thereby negating the need for dehorning, an unpleasant process that is routinely carried out for both farmer and animal safety.

Relative to GE crops, the commercialization of GE food animals is at a nascent stage. Subjecting the GE animal approval process to prolonged political interference and unaccountable regulatory delay is having an inhibitory effect on the commercialization of this potentially beneficial technology. Focusing solely on the potential risks associated with GE animals while ignoring both the known risks associated with current production practices, and as importantly the potential benefits, results in an uneven evaluation of the potential of this technology. World-wide GE regulations have disproportionately focused only on the potential, and largely unrealized, risks associated with GE technology. While regulation to ensure the safety of new technologies is necessary, in a world facing burgeoning demands on agriculture from population growth, economic growth, and climate change; creating an impassable regulatory hurdle for promising technologies is a roadblock that global food security can ill afford.

[1] Brookes G, Barfoot P: The global income and production effects of genetically modified (GM) crops 1996-2011. GM Crops and Food: Biotechnology in Agriculture and the Food Chain 2013, 4:74-83