Most of the work has been conducted using the laboratory mouse. Translation of the technology to the domestic animal has not met with great success, partly because of the genes and promoters chosen and partly because of the difficulty and expense in obtaining large numbers of suitable early embryos for gene incorporation. An efficient gene incorporation system is cow embryos ideally requires the development of a number of novel embryological techniques. They include in vitro maturation and fertilisation of bovine oocytes from abattoir- sourced ovaries, in-vitro culture to allow the development of fertilised embryos to readily transferable stages, satisfactory techniques for incorporating genes into the embryo and techniques such as embryonic cloning to exploit the transgenic cattle produced. The various techniques, their problems and successes are described in depth in this paper.
A research programme has been initiated to link embryology, dairy science and molecular biology techniques with the aim of producing transgenic cattle with modified milk composition.
Keywords: NZSAPAB; Embryological techniques; gene injection; cattle; transgenic cattle