Transgene-mediated modifications to animal biochemistry

The application of gene-transfer technology to domestic animals provides a way for the introduction of genes encoding biochemical pathways that are currently nonfunctional in these animals. This might provide a mechanism for increasing the availability of specific substrates that currently limit certain production characteristics, such as the production of wool. The progress and problems associated with recent attempts to transfer a cysteine biosynthetic pathway and a glyoxylate cycle to sheep are discussed, in addition to the extension of this concept to other biochemical pathways.