Intake of High Producing Holstein Cows Grazing Pasture or Fed a Total Mixed Ration

(week 4). Intake was estimated in week 4 by dosing twice daily with 5 g Cr 2 O 3 for 10 days. Fecal samples were collected twice daily on days 7 to 11 of Cr 2 O 3 dosing, with pre-grazing pasture being sampled on days 6-10 of dosing. Fecal output, calculated from fecal chromium concentrations, and in vitro digestibility (IVDMD) were used to calculate intake (Parker et al. 1989). The intake of cows fed TMR in confinement was measured by weighing feed offered and refused on 5 days. Nutrient composition of pasture and TMR was determined according to AOAC procedures. Data were analyzed using the general linear models procedure of SAS (1990), with a pre-trial covariate and the repeated measures procedure applied to data collected across transition and production periods.