In four laboratories, a total of 52 adult rabbits were fitted with a single T glass cannula at terminal ileum. After surgery recovery, animals were fed ad libitum with the same batch of a diet labelled by the addition of ytterbium attached to fibre particles. The effect of time during the ileal digesta collection period (morning and evening) on ileal digesta composition and ileal digestibility of DM, CP, NDF and ADF was evaluated. Compared with the evening samples, the morning samples had higher content of ytterbium (+5%) and CP (+43%) but lower contents of NDF (-9%) and ADF (-11%). Consequently, ileal digestibility for DM, NDF and ADF resulted in higher figures when calculated from the morning samples as opposed to those from the evening samples. However, CP ileal digestibility results were just the opposite. When compared with the results obtained as a reference value from the 24-hour samples (a pool of collections obtained in the morning, evening and night), the data average from the morning and the evening samples did not differ significantly. Therefore, it is possible to reduce the number of collections and simplify ileal digesta sampling by avoiding night collections.
ileal digestibility; sampling procedure