Total tract digestibility of DM was evaluated on N fecal content as already made by Lohakare et al. [11] for dairy calves fed MR twice a day and weaned at 70 days. It was not influenced by feeding program: OM digestibility averaged 78.9% on week 4 and 77.1% on week 9 which is in accordance with results obtained by Lohakare et al. [11]. However, our sampling periods for digestibility measurements did not correspond with periods where rumen pH and Eh differed between OAD and TAD calves, which could have masked a link between changes of rumen milieu and total tract digestibility.