In the change-over trials (n=121 diets) DMI and ECM
yield were slightly greater (18.4 versus 18.0 and 26.8 versus
26.2 kg/day), and the cows were in a later stage of lactation
(DIM 112 versus 94) than in the continuous trials (n=96
diets). Concentrate DM intake (7.1 and 8.0 kg/day) and proportion
of total DM intake (0.37 and 0.43) were smaller in
the change-over trials compared with the continuous trials,
but the s.d. of CDMI was similar (2.9 kg/day) for the both
trial types. Marginal responses to increased CDMI in total
DMI and milk production variables were similar irrespective
of experimental design (Table 2).