Genetic modification (GM) in livestock involves altering an animal’s genetic material by adding, changing, or removing specific DNA sequences in a way that does not occur naturally. This technology is being researched in cattle to introduce desirable traits. However, the commercial presence of genetically modified cows in the food supply is highly regulated and extremely limited. Only a select few genetically altered cattle have received regulatory determination allowing their products into the food chain.
Genetic Engineering Versus Selective Breeding
The modern process of genetic engineering is fundamentally different from selective breeding, the traditional method used to improve livestock over millennia. Selective breeding relies on choosing animals with naturally occurring desired traits, such as high milk production, and breeding them to pass those traits to the next generation. This process works only with the natural genetic variation already present within a species, making it a slow and gradual form of genetic improvement.
Genetic engineering, by contrast, allows for the precise, targeted manipulation of an organism’s genome using technologies like CRISPR-Cas9. This technique can insert, delete, or modify specific genes to introduce a trait that would never arise naturally or that would take many generations of traditional breeding to achieve. The resulting change is permanent and heritable, meaning it is passed down to the animal’s offspring.
It is important to distinguish genetic modification from the use of hormones like recombinant bovine somatotropin (rBST). rBST is a synthetic version of a protein hormone naturally produced by cows and is injected into dairy cattle to temporarily increase milk production. This chemical treatment stimulates a physiological response in the animal, but it is not a permanent alteration of the cow’s genetic code passed to its progeny.
Current Status of Regulatory Approval
For genetically modified animals to enter the food supply in the United States, they must undergo a rigorous approval process with the Food and Drug Administration (FDA). The FDA treats an intentional genomic alteration (IGA) in an animal as a new animal drug. Developers are required to demonstrate the product’s safety for the animal, the environment, and human consumers.
The first genetically engineered food animal to receive full FDA approval was the AquAdvantage salmon in 2015, modified to grow to market size faster than conventional counterparts. This approval set a high standard, requiring more than a decade of review and data. In late 2020, the FDA approved the GalSafe pig, whose meat is modified to eliminate a sugar molecule that can trigger a rare allergy in humans.
Regarding cattle, the FDA made a “low-risk determination” in 2022 for a specific line of genome-edited Angus cattle. These cattle were modified using CRISPR technology to express a slick, short-haired coat that improves their heat tolerance, mimicking a trait found naturally in some other cattle breeds. This determination was a streamlined regulatory decision, allowing the products from these animals and their descendants to enter the food supply without a full New Animal Drug Application approval.
Despite the regulatory pathway being cleared for the heat-tolerant cattle, commercial availability remains limited. In many international markets, such as the European Union, no GM cattle are approved for food production. The low-risk determination applies only to a specific, well-characterized change equivalent to a natural mutation. Future GM cattle with more complex or novel modifications will likely face the longer, full approval process.
Traits Targeted by Bovine Genetic Modification
Scientists are pursuing genetic modification in cattle for a range of traits aimed at improving animal health, production efficiency, and environmental sustainability, primarily in research settings. One significant area of focus is developing disease resistance to protect herds from common and costly illnesses. Researchers have worked on modifications to enhance resistance to Bovine Viral Diarrhea Virus (BVDV), a major viral pathogen causing significant economic losses worldwide.
Another important target is mastitis, a painful udder infection common in dairy cattle that often requires antibiotic treatment. Some research involves engineering cows to produce milk with enhanced antibacterial properties. These modifications are designed to improve animal welfare and reduce the reliance on antibiotics in livestock farming.
Genetic modification is also being explored to address welfare concerns by creating naturally hornless, or “polled,” cattle. Traditional dehorning is a painful procedure necessary for herd safety. Scientists have used gene editing to introduce the polled trait into dairy breeds like Holsteins, aiming to produce cattle born without horns and eliminate the need for the practice entirely.
Furthermore, some modifications aim to adapt cattle to a changing climate and improve feed efficiency. The slick-coated cattle, which are better able to regulate their body temperature in hot environments, are an example of climate adaptation already cleared for the food supply. Other research focuses on altering milk protein composition, such as eliminating the protein beta-lactoglobulin, to potentially create less allergenic milk.