Which Animals Are Used
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Farmed animals are used in a number of ways: in research on agricultural methods, research into human health problems, and as “bioreactors” to generate biological products used in all kinds of research and testing.
Importantly, animals used in agriculture-related “food and fiber” research are not covered by the Animal Welfare Act (AWA). The agriculture industry and its allies in government agencies fund research to maximize “productivity,” which means faster growth and fewer losses—often with experiments using genetic engineering. It also includes handling crises such as rapid spread of disease that are inherent in factory farming.
Farmed animal species are also used as models of human disease, for testing of medical devices, and for research in cloning and genetic engineering. In January 2008, the Food and Drug Administration (FDA) announced that products from cloned cows, pigs, and goats can be sold as food without labels and in 2009, the FDA approved the first drug produced from a transgenic animal. Farmed animals used in biomedical research and testing (excluding birds bred for research) are covered by the AWA.Read more about farmed animals used in research and testing.
More than 52,000 pigs were held in research labs in 2021 and of those, nearly 70% were used in experiments causing pain and distress, according to AAVS analysis of data released by the U.S. Department of Agriculture (USDA). Due to the pig’s large adult size, a variety of mini- and micro-pigs, who consume fewer resources, are easier to handle, and require less space, have been created by laboratories through genetic manipulation and selective breeding. These pigs are used as models for human disease and are often bred to be free of specific pathogens, living in sterile environments.
Pigs are the animal of choice to study xenotransplantation, the transfer of cells, tissue, or organs from one species to another, because they mature quickly, have large litters, and their organs are similar in size to human organs. Beyond the ethics of using animals to supply organs to be transplanted into humans, there are other concerns surrounding this technology as pigs are genetically engineered to reduce the risk of hyperacute rejection. However, pigs can still carry retroviruses that could potentially cause severe illness in humans. Pigs are also used to study cardiovascular, respiratory, gastrointestinal, and pancreatic diseases; neurological disorders like stroke and Parkinson’s disease; wound healing and plastic surgery, as well as in lethal trauma and surgical training.
Transgenic pigs have also been created in agriculture research. The Enviropig was engineered to produce less phosphorus in their waste to help reduce environmental pollution, but, due to a lack of interest, this research of ended in 2012. The GalSafe pig, genetically engineered to not carry sugar that can cause a severe allergic reaction in some people, was approved for use as food by the Food and Drug Administration (FDA) in 2020, although it’s too expensive to produce to realistically be sold on the market. In 2023, the FDA gave its investigational authorization to Washington State University to have five gene-edited pigs for human consumption. The pigs were used to show that desirable traits for improved food production can be achieved through gene-editing faster than selective breeding.
More than 12,000 sheep were held in labs in 2021, with over 55% being used in procedures causing pain and distress, according to AAVS analysis of data released by the USDA. Sheep, particularly females (ewes), are preferred because they are relatively easy to house, docile, and have large bodies, making it easier to perform multiple experimental procedures on them.
Sheep are used in basic biomedical research and as models for human organ systems. In studying neurodegenerative disorders, sheep have been genetically engineered to be a model for Huntington’s disease and exposed to toxins that destroy neurons to induce Parkinson’s disease. They are also commonly used to study cardiovascular and respiratory tract diseases, as well as in orthopedic and musculoskeletal research. Additionally, sheep are used in gene therapy research, reproduction studies, and vaccine development and testing.
Sheep are also used in agriculture research geared towards ‘improving’ reproductive techniques, nutrition, and parasite resistance, as well as genetic studies to enhance desired traits, such as in wool production, to maximize the profitability of these animals.
Less than 8,000 cows are held in U.S. labs, according to AAVS analysis of data released by the USDA. They are frequently used in reproductive research, particularly for in vitro fertilization, as well as in behavioral studies and animal disease research and testing. Cows have also been genetically engineered to make human antibodies that can be used to study diseases, including HIV and SARS-CoV-2. Due to their large size, cows can produce large quantities of antibodies that are collected from their blood, colostrum, and milk. Additionally, the fetuses of slaughtered cows are harvested and their hearts punctured to collect blood to make fetal calf serum, which is used as a growth medium for cell cultures.
Cows are also subjected to experimentation to ‘improve’ agriculture. For example, calves less than two months old on dairy farms are routinely disbudded, a painful procedure done to prevent adults from growing horns. One company claimed to have gene-edited dairy cows to be hornless, but through this process unintentionally inserted bacterial DNA into the cow genome, resulting in a genetically engineered animal that was not approved for human consumption. The agriculture industry also supports research to ‘improve’ the welfare of farmed animals. For example, cows have been genetically engineered to be more heat-tolerant and better able to withstand hot weather instead of providing better living environments for animals.
Although goats are not commonly used in biomedical research in the U.S., over 14,000 goats were held in labs in 2021, according to AAVS analysis of data released by the U.S. Department of Agriculture. Goats are frequently forced to endure painful processes to produce polyclonal antibodies, which are widely used for a variety of research and diagnostic purposes.
Goats are also genetically engineered to be used as living bioreactors to generate recombinant proteins that can be used to make various pharmaceutical products. In 2009, the Food and Drug Administration approved the first human drug produced in a transgenic animal, ATryn, an anticoagulant drug harvested from the milk of transgenic goats.