Transgenic Cattle - The only successful transfection technique in cattle is microinjection of fertilized ova, which may either be recovered surgically or may be obtained from ovaries extracted from slaughtered cows and cultured in vitro.

The two chief objectives of transgenic production are as follows:
(1) increased milk or meat production and
(2) molecular farming.
Several human genes have been successfully transferred in cows and expressed in the mammary tissue; the protein is secreted in milk from where it is easily harvested.