A review is given of information available to produce a dynamic mechanistic model of amino acid uptake and subsequent intracellular metabolism including milk and tissue protein synthesis within the lactating bovine mammary gland. To be a truly mechanistic representation of actual biology the model must address each AA individually, uptake via transporters must be described bidirectionally as has been observed in vitro and in vivo, and the requirements for all mammary origin milk proteins including α-lactalbumin and β-lactoglobulin must be addressed. A conceptual framework for such a model is advanced.