MAMMARY-GLAND EXPRESSION OF TRANSGENES AND THE POTENTIAL FOR ALTERINGTHE PROPERTIES OF MILK

Transgenic animals are a useful in vivo experimental model for assessi ng the ability and impact of foreign gene expression in a biological s ystem. Transgenic mice are most commonly used, while transgenic sheep, goats, pigs and cows have also been developed for specific, ''applied '' purposes. Most of the work directed at targeting expression of tran sgenes to the mammary gland of an animal, by using a milk gene promote r, has been with the intent of either studying promoter function or re covering the desired protein from the milk. Transgenic technology can also be used to alter the functional and physical properties of milk r esulting in novel manufacturing properties. The properties of milk hav e been altered by adding a new protein with the aim of improving the m ilk, not of recovering the protein for other uses.