At a specific digestible ERDP content the diet of an individual cow will be correctly balanced. When the cow is offered two foods, one in excess of predicted requirements for ERDP, the other deficient in ERDP for the predicted level of production, then the cow has the opportunity to select a diet, which exactly meets her requirements for ERDP assuming it meets the predicted milk yield. The aim of this experiment was to examine if lactating dairy cows can choose a level of ERDP concentrate appropriate to their requirements.

Twenty four mid lactation, Holstein-Friesian dairy cows were used for this experiment. The experiment was of latin square design and repeated measures analysis was used in SAS. They were fed grass silage (DM, 295g/kg; CP, 175g/kgDM; 11.5MJ/kgDM) ad libitum via the LUCIFIR (Leeds University Individual Feed Intake Recorder) system which enabled all meals to be recorded.