This chapter discusses the possibility of applying more integrated approaches when evaluating nutritional strategies for dairy cows, simultaneously in detail and from several aspects. The different levels of aggregation that may be covered by models are shown. Primarily, the chapter handles the integration of details at the sub-cow level to the cow level and explains several physiological aspects and consequences of nutrition strategies for dairy cows. However, a nutritional strategy that appears more successful at the cow level does not necessarily need to be more successful at the level of the whole farming system, including forage production, import of concentrates and production and application of manure. For this reason, a limited attempt has been made at integration with other aspects of the whole farming system.