The on-farm extraction of proteins directly from raw whole milk is a promising approach for the production of minor, high-value proteins from conventional milk and for the production of recombinant proteins from the milk of transgenic animals. The main advantage of the stirred tank process is that protein extraction is rapid and is achieved in a single step without the need for a pre-treatment. It also includes the minimization of microbial growth and the potential for batch traceability between individual animals and final product lots.