Cattle that are genome edited to grow short, slick hair are the first genetically modified cattle that US authorities will allow to be raised for food.
Food and Drug Administration officials announced March 7 that they found no safety concerns related to the modified Angus cattle, and meat from descendants of those cattle could be available in the US and other countries within two years. Though intentional genetic modifications are subject to FDA regulation as drugs, agency officials said the low-risk determination let them apply enforcement discretion and allow production of the cattle without an application for drug approval.
FDA officials have previously applied such risk-based discretion to fish that were modified to fluoresce and animals that are from food-producing species but intended only as models for disease.
In 2015, agency officials granted the first approval for a genetically engineered food animal, a line of Atlantic salmon modified to grow to market size in half the time of conventional salmon. In December 2020, the agency also approved a genetic alteration in pigs that eliminates a sugar molecule known to trigger a rare allergy in humans, and those pigs may be sold for medical uses and meat.
According to an FDA risk assessment, the modified cattle are products of the company Acceligen — a subsidiary of Recombinetics — which used CRISPR-Cas9 gene editing in Angus cattle to disrupt a prolactin receptor gene, in doing so mimicking a mutation that results in the short , slick hair that is found on other types of cattle that are raised for beef in tropical and subtropical environments. The document notes that traditional breeding methods have produced Holstein cattle lines with the same slick-haired phenotype.
Agency officials said in the risk assessment that they consider the modification to be equivalent to naturally occurring mutations. In the announcement, officials also said the modifications may reduce temperature-related stress in cattle, which also could aid beef production.
The modified cattle raised by Acceligen have had similar health and growth to conventional cattle, except for one male calf that died of congestive heart failure, FDA information states. The risk assessment notes that congestive heart failure is known to affect cattle with Angus-influenced genetics, and the calf inherited genes associated with the disease from its nonmodified parents.
Though the risk assessment notes that the company and FDA officials found unintended genetic modifications, “None of the identified unintended alterations are expected to result in changes to protein expression based on their locations and available genome annotation.”
“Based on the molecular characterization and animal health data, FDA determined these unintended alterations do not pose any safety concerns for the cattle or for humans consuming food from the cattle,” the document states.
Sabreena Larson, chief operations officer for Acceligen, said in a message that the company is pleased with the low-risk determination and the “slick” trait “will be used to transform beef production to be more sustainable and improve animal welfare in warmer climates. ” She declined further comment and referred other inquiries to materials published by the FDA.
Dr. Stewart Bauck is a member of the American Association of Bovine Practitioners’ Genomics Committee. He has worked closely with some of the Acceligen scientists in the past, and is the senior director of special projects for Neogen, which performs genomic testing on cattle and other animals around the world. He said the FDA’s decision to allow Acceligen’s modifications was a pleasant surprise, and the conditions of that permission could have implications for other genetic modifications.
He noted that Acceligen gained FDA permission to sell products — including semen, embryos, and meat — derived from only two modified cattle and their progeny.
Dr. Bauck said that suggests the agency is applying enforcement discretion only to individual genetically modified animals that have been subject to genetic sequencing and analysis rather than applying that discretion more broadly to the modifications themselves. If so, Acceligen can use those two modified cattle to create breeding lines, but modifying more cattle to create additional breeding lines with the same or other genetic changes would require going through the same FDA analysis and decision-making process every time.
Dr. Bauck also sees potential that other modifications could follow a similar path. Hornless — or polled — cattle for example, can be produced through conventional breeding, but that would require extensive work to select for that trait while maintaining the high milk production of existing breeds. Genetic modification could hasten that selection process.
FDA spokesperson Juli Putnam provided a statement in response that Acceligen asked FDA officials to review two animals and the products of those animals and their offspring, and agency officials could consider broader risk-based decisions.
Dr. Bauck said cattle with heat stress grow more slowly, produce less milk, and have more difficulty producing offspring. He said Acceligen’s modification may expand the geographic range to raise cattle and improve production in tropical environments.
But he also expects public acceptance of meat or milk from those cattle will depend how those products are labeled and whether food supply chains segregate the products from meat or milk of conventional cattle.
The FDA’s announcement links to the risk assessment.