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Genetically modified crops and enzymes derived from genetically modified micro-organisms are widely used in animal feeds. Feed mixtures are principally used for poultry, pigs and dairy cows and contain a range of ingredients, including maize and other cereals and oilseeds such as soybeans and canola. Currently, a significant portion of soybeans, canola, and maize produced is genetically modified.
Safety assessment studies in many countries have compared the new genetically modified feeds with their conventional counterparts. These comparisons address, for example, the nutritional composition of feeds as well as their effects on animals and on humans eating the resulting animal products.
Studies have also considered the fate of modified DNA in the digestive tract of the animal. Results indicate that both modified DNA and proteins are rapidly broken down in the digestive system, and no adverse effects have been reported on either growth, body-weight, feed conversion, nutrient composition, or milk production. An FAO review considered it extremely unlikely that genes may transfer from genetically modified plants to disease-causing bacteria. Nevertheless, it advised against using genes which determine resistance to antibiotics that are critical for treating human infectious diseases in genetically modified plants. More...
As of 2004, no genetically modified animals have yet been used in commercial agriculture anywhere in the world. However, the possibility of transferring genetically modified characteristics to several livestock and aquatic species is being studied.
Reports addressing those potential environmental concerns recommend that genetically modified animals should be evaluated in comparison with their conventional counterparts.
Adverse environmental impacts from escaped genetically modified animals are less likely for livestock breeds than they are for fish. This is because most farm animal species have no close wild relatives remaining and farm animal reproduction is generally confined to managed herds and flocks.
The use of genetically modified animals could also lead to environmental impacts through changes in the animals themselves or in the management practices associated with them. Genetic modifications could for instance reduce the amount of manure and methane emissions produced by livestock and aquaculture species. Furthermore, they could increase their resistance to diseases, which would promote lower antibiotic usage. However, some genetic modifications could lead to more intensive livestock production associated with increased pollution. The question of environmental harm is therefore considered less a question of the technology itself than of the capacity to manage it.
An additional factor that should be taken into account with livestock biotechnology is the possible effect on the welfare of animals. At present, the production of genetically modified and cloned animals is extremely difficult, with high mortality during early embryonic development and success rates of only 1-3%. Moreover, in the genetically modified animals that are born, the inserted genes may not function as expected, often resulting in anatomical, physiological, and behavioural abnormalities.
Therefore, in addition to economic considerations, the possible environmental impacts or effects on the welfare of animals are to be taken into account in livestock biotechnology. More...
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