The invention relates to the milk of a transgenic non-human mammal. The milk is characterized in that it contains heterologous components produced as the secondary gene products of a heterologous gene contained in the genome of the transgenic non-human mammal. The heterologous gene encodes a heterologous catalytic entity such as a human enzyme selected from the group consisting of glycosyltransferases, phosphorylases, hydroxylases, peptidases and sulfotransferases. Especially useful in the practice of the invention are human glycosyltransferases. The desired heterologous components include oligosaccahrides, glycoconjugates. Specifically exemplified, is the production of 2'-fucosyl-lactose in the milk of transgenic mice which contain and express a transgene encoding .alpha.-1,2-fucosyltransferase operatively linked to a mammary gland specific promoter. The oligosaccahrides and glycoconjugates may be isolated from the milk of the transgenic mammals and used in the preparation of pharmaceuticals, diagnostic kits, nutritional products and the like. The whole transgenic milk may also be used to formulate nutritional products that provide special advantages. The transgenic milk may also be used in the production of specialized enteral nutritional products.