We speak about genetic modification when one or more genes (DNA-molecules with a certain function within the cell or organism) or combinations of DNA-molecules (so-called gene-constructs) are introduced into the animal involved. One method which is often used is that the DNA-molecules are injected with a very fine needle in the fertilized egg. We speak about transgenic animals when the genes come from a different species. This method may be used for different purposes: to increase production in animal husbandry, to make animals resistant to diseases, or to change animals in such a way that they produce certain medically useful products in their milk. Once the genetically modified animals are developed they may also be multiplied by cloning techniques.
Recommended CitationVerhoog, Hank, Morality and the 'Naturalness' of Transgenic Animals, Animal Issues, 2(2), 1998.