Abstract: Although producing mammary gland bioreactor showed great advantage over many years, there are many deficiencies in the existing general approach. The level of transgenic expression was low in transgenic animals and the diversity was more great because of the position effect of transgene and the artificial recombination of the gene elements. But the transgene could be integrated precisely in the chromosome using gene targeting, somatic cell nuclear transfer also shows the great efficiency in saving time and cost, especially refer to the livestock. The superiority, technical challenges, the solution, and the prospects for the combination of gene targeting and nuclear transfer were briefly discussed.

Key words: gene targeting; nuclear transfer; transgenic animal; mammary gland bioreactor