. "Subreport: Methods and Mechanisms of Genetic Manipulation and Cloning of Animals." Safety of Genetically Engineered Foods: Approaches to Assessing Unintended Health Effects. Washington, DC: The National Academies Press, 2004.
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Safety of Genetically Engineered Foods: Approaches to Assessing Unintended Health Effects
A number of animal biotechnologies have already been developed and are in commercial use. One such example is recombinant-derived bovine somatotropin (bST). Recombinant bST has been approved by the Food and Drug Administration for use in the U.S. dairy industry and is also approved for use by 18 other countries (CAST, 2003; Etherton and Bauman, 1998). Commercial use in the United States began in early 1994 and has increased to the point that about one-half of all U.S. dairy herds, comprising more than 3 million cows, are receiving bST (Bauman, 1999). Milk yield increases in response to bST typically range from 10 to 15 percent (about 4–6 kg/d), although larger increases may occur when the management and care of the animals are excellent (Bauman, 1992; Chillard, 1989; NRC, 1994). It is, however, important to distinguish the use of bST from other biotechnologies, such as transgenic or cloned animals. Application of recombinant bST is a biotechnology in which a recombinant-derived protein is administered by injection to the recipient animal without changing the animal’s genetic composition or genome.
The application of genomics—the study of how the genes in deoxyribonucleic acid (DNA) are organized and expressed—and bioinformatics in animal agriculture will provide new genetic markers for improved selection for desired traits in all livestock species. Transgenic biology provides a means of altering animal genomes to achieve desired production and health outcomes of commercial value and societal importance. For example, genetic modification of animals may lead to technologies that reduce the major losses that occur during the first months of embryogenesis. Biotechnology also offers potential to animal agriculture as a means to reduce nutrients and odors from manure and volume of manure produced, resulting in animals that are more environmentally friendly (CAST, 2003).
The advent of techniques to propagate animals by nuclear transfer, also known as cloning, potentially offers many important applications to animal agriculture, including reproducing highly desired elite sires and dams. Animals selected for cloning will be of great value because of their increased genetic merit for increased food production, disease resistance, and reproductive efficiency, or will be valued because they have been genetically modified to produce organs for transplantation or products with biomedical application.
Before entering the marketplace, new agricultural biotechnologies are evaluated rigorously by the appropriate federal regulatory agencies to ensure efficacy, consumer safety, and animal health and well-being. The development of technologies to clone animals used for food production has raised the question of whether there are unintended compositional changes in food derived from these animals that may, in turn, result in unintended health effects.