TRANSGENIC ANIMALS IN AGRICULTURE

Abstract

The first reports on the effects of human growth hormone in transgenic mice, engendered speculation about how genetic engineering could be applied to improve livestock for use in agriculture. However, 30 years later this promise has yet to be realised as there are no GE animals approved for food consumption anywhere in the world. Initial work mostly either concentrated on the production of animals (sheep and swine) with deregulated growth hormone (GH) genes or represented work to improve our understanding of gene constructs for the control of gene expression. Although a variety of GH transgenic lines of livestock were successfully produced, most had compromised health and were not suitable for further development. However, several lines of transgenic farm animals and fish could be potentially useful genotypes for use in production agriculture, including GH pigs, phytase pigs, lysozyme goats, lactoferrin cows, and lactalbumin pigs. To date, none of these lines have yet been approved for human consumption and thus have not made it into production. Many of these lines have been placed in frozen storage or have been lost and would need to be redeveloped. The reasons for this are varied and include simply retirement of the developer, through to insufficient funds, pressure from anti-biotechnology activists, lack of a regulatory process, public opposition, or lack of a perceived need by industry. The combination of these factors has led to a virtual cessation of research and development of transgenic animals for use in agriculture in North America, Europe, and Australia, early leaders in developing this technology, and the emergence of programs in places such as Brazil and China, where the next generation of GE animals for agriculture will be developed. However, recent advances in the methodology to produce transgenic animals, such as the use of transposons or site-directed nucleases such as TALENs, may lead to renewed efforts to develop targeted GE animals for use in agriculture.