The first genetically modified animal was a mouse, which was created in 1974 by Rudolph Jaenisch, a virologist at the Salk Institute, and Beatrice Mintz, a mouse embryologist at Fox Chase Cancer Center. This mouse – as well as its many successors – was created to facilitate scientific research. 

It wasn’t until 1989 that someone initiated the effort to genetically modify an animal used for food, an Atlantic salmon – what is now known as the AquAdvantage salmon – which was genetically modified to grow larger and faster using DNA from a Chinook salmon and an ocean pout. An FDA file on the AquAdvantage salmon was opened in 1995, with supporting documentation being submitted until 2009. The FDA recommended approval in 2010, but the salmon didn’t ultimately receive FDA approval until 2015.

Much has changed since the development of the genetically modified salmon, including advancements in technology, the mapping of the entire genomes of numerous organisms, the infusion of significant venture capital funding, and perhaps most significantly, the development of new GMO techniques such as TALEN and CRISPR. Combined, these changes have served to increase the development of genetically modified animals through streamlined modification processes, abbreviated regulatory determination or approval timelines, and reduced cost.  

Some of the modified animals developed thus far have been purely experimental, but others have been driven by specific goals, such disease resistance, heat tolerance, or the facilitation of xenotransplantation (i.e., transplantation between species). Along the way, developers have created fluorescent rabbits, double-muscle pigs, male pigs that never advance beyond puberty, and the ill-fated hornless cow. 

Only a couple of genetically modified animals have yet been approved by the FDA for use as food. However, it is important to note that of those, not all require special labeling. Below are some examples of genetically modified animals that have been or are being developed.

Pigs

The first pig – and the second genetically modified animal – to be approved by the FDA for food was the GalSafe pig, which made its debut in 2020 and was developed by the U.S. pharmaceutical company Revivicor for use in xenotransplantation. Although the GalSafe pig was genetically modified to help address potential organ rejection issues (through the elimination of GGTA1 gene and insertion of human DNA), Revivicor also sought to have the pig approved for food, which would greatly facilitate the dispensation of any remaining post-organ-harvest pig parts (i.e., meat). The FDA approved the pigs with a number of specific requirements and restrictions, including segregation during rearing and slaughter and the labeling of any meat derived from the GalSafe pig. The company originally stated that it planned to sell any derived meat on its website. Revivicor hopes to enter commercial production for a “specialized market” later this year.

Egenesis is another developer that is creating genetically modified pigs for xenotransplantation. Located in Cambridge, Massachusetts, the company was co-founded by George Church, a geneticist at Harvard Medical School. Using CRISPR, Egenesis has made 70 edits to the pig’s genome. These changes are designed to address a range of potential issues, including porcine retroviruses and incompatible proteins, as well as to insert human genes to help address rejection issues. As of last summer, Egenesis had 400 genetically engineered pigs at a research facility in the Midwest. The company is in the early stages of animal trials and as of last summer had not yet submitted the pig to the FDA for approval. 

A British genetics firm, Genus, which has research facilities in the U.S., has used CRISPR to create a line of genetically engineered pigs that are resistant to porcine reproductive and respiratory syndrome (PRRS) virus. As part of this effort, the company went beyond creating a single genetically modified “proof-of-concept” pig. Four individual pig lines were modified, and multiple generations were crossbred to create a small herd suitable for the initiation of commercial pork production. Genus is now working with regulators in the U.S. and other countries in seeking approval for commercial production. It hopes to have FDA approval by the end of the year.

Cows

In 2020, scientists at U.C. Davis announced the development of a bull named Cosmo, which had been genetically engineered using CRISPR to ensure that the majority of its progeny present as male. Through the insertion of an SRY gene in chromosome 17, which is responsible for initiating male development, scientists hoped that the majority of Cosmo’s progeny would present as male regardless of whether they had inherited a Y chromosome. So, in theory, 50% would be male (XY) and half of the remaining 50% that would be genetically female (XX) would present as male. This could potentially have significant advantages for the cattle industry. This effort was not undertaken with the expectation that these modified cows would immediately enter the food supply chain but instead to study the trait and its potential for heritability in subsequent generations once Cosmo had reached sexual maturity and could be used for breeding. 

The first cow to be approved by the FDA for food is PRLR-Slick cow, informally known as the Hairslick cow, which was developed by Acceligen, a subsidiary of Recombinetics. Two Angus cows were genetically modified using CRISPR to have short slick hair more typical of cattle breeds raised in tropical climates, making it more suitable for the rising temperatures associated with climate change. In its review, the FDA did identify off-target effects in the altered cow but determined that these effects did not pose a safety concern for the cows or for humans. Because the trait already exists in other cattle species, the FDA imposed no rearing, slaughter, or labeling restrictions or requirements on the two cows or their progeny. It is unknown whether or where these genetically modified cows are being raised or bred or when they might enter the food supply chain.

Last year, scientists announced the creation of a bovine viral diarrhea virus (BVDV)-resistant cow. The cow, named Ginger, was developed through a collaboration between scientists at USDA’s Agricultural Research Service (ARS), the University of Nebraska-Lincoln, the University of Kentucky, and Acceligen/Recombinetics. BVDV is highly contagious and affects cows worldwide, routinely costing the U.S. cattle industry billions of dollars each year. Using CRISPR, the scientists altered Ginger’s primary BVDV cellular receptor (CD46) to reduce susceptibility to infection. When exposed to BVDV, Ginger remained infection free with no observable adverse health effects. However, scientists noted that although Ginger appeared to be a success, more monitoring and research would be needed.

Chickens

Scientists at University of Edinburgh, Imperial College London, and the Pirbright Institute have collaborated to create a bird flu-resistant chicken. Using CRISPR, the scientists altered the ANP32A protein, which serves as host for avian flu virus replication. When exposed to H9N2 avian flu, 9 of 10 modified chickens remained healthy and resistant to the virus. However, when the chickens were exposed to abnormally high levels of the virus, the results were not as promising. In addition, it was also determined that the virus in the genetically modified chickens had mutated, enabling it to use other proteins (i.e., ANP32B and ANP32E) to replicate. Thus, in their announcement, the scientists were quick to state that this was only the first step, and their work would continue.

Researchers at Hiroshima University have developed what are being touted as genetically modified “allergy-free” chicken eggs. The eggs, technically referred to as ovomucoid (OVM)-knockout eggs, were developed using TALEN. Inasmuch as the trait is heritable, laying hens derived from those eggs reportedly produce allergy-free eggs. Egg protein is a well-known allergen and as such poses a safety hazard both in terms of food as well as use in other applications, such as the manufacture of vaccines. Researchers were quick to point out that the exact degree of allergy reduction (versus allergy free) has yet to be determined and will require further safety testing and trials.

Israeli scientists from the Volcani Institute announced the development of genetically modified hens that lay eggs from which only female chicks will hatch in an attempt to preclude the culling of male chicks. Referred to as Golda hens, the modified chickens lay eggs that are then exposed to a blue light for several hours; the light activates the edited DNA, preventing the development of any male embryos while reportedly having no effect on female embryos. At the end of 2022, the developers reported that the chickens had been submitted for review by the FDA and Israel’s Agriculture Ministry. The ultimate goal is to license the technology through an associated company, Poultry by Huminn. 

Non-GMO Project’s Standard defines all crops and products developed using biotechnology, including new gene-editing techniques, as GMOs. We share this information to further one of the Project’s primary goals of creating greater transparency in the supply chain, ensuring you have the information you need to make the best choices for you, your brand, and your family. 

Please note that the information herein is for general informational purposes only and is based on the linked sources above.

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