Our aim was to evaluate the effectiveness of inserting a cannula into the distal ileum for use in future digestibility studies in preweaning calves. A T-cannula was placed in the terminal ileum ca. 5 cm anterior to the ileocecal junction in 2 calves at 15 d of age, and 2 paired non-cannulated calves were used as controls. All calves were fed 2X daily a commercial milk replacer (MR) at a rate of 2% (DM) of BW adjusted weekly. Starter was offered ad libitum from wk 6. Body measurements were recorded weekly; intake and health scores were recorded daily. Samples of digesta were collected weekly during 12 h continuously (after a.m. feeding) during 2 consecutive days. Data collected during the 4 wk after post-surgical recovery (starting d 30) were compared using the MIXED procedure in SAS. Initial BW (wk 4; 47.1 ± 2.9 kg; P = 0.74), mean BW (81.6 ± 10.3 kg; P = 0.16), ADG (894.8 ± 440.8 g/d; P = 0.20), MR (1.41 ± 0.27 kg/d; P = 0.13) and water intake (0.8 ± 0.6 kg/d; P = 0.89), and body dimensions were not affected by cannulation. However, starter intake (0.07 vs 0.21 kg/d; P = 0.06), final BW (wk 8; 89.2 vs 94.6 kg; P = 0.05) and gain:feed (0.57 vs 0.65; P = 0.03) were lower in cannulated calves. There were no effects on health (fecal, nasal, respiratory, and ear scores), rectal temperature (38.3 ± 0.4°C; P = 0.58), or in the odds of incurring diarrhea (P = 0.57) or being medicated (P = 0.35). Flow of digesta samples (46.4 ± 0.04 g/h) tended to increase linearly after feeding, while there was a quadratic effect of time (P < 0.01) in digesta pH (Table 1). There were no differences across weeks or among calves in fresh weight (0.72 ± 0.13 kg/w/calf), DM (12.4 ± 1.2%) or pH (7.1 ± 0.6) of digesta. Despite the expected negative effect on BW and gain:feed, this technique permitted sampling of representative ileal digesta while allowing satisfactory growth and health. Table 1. Characterization of digesta sampling

Item	Hour after feeding												P-values
1	2	3	4	5	6	7	8	9	10	11	12	Linear	Quad.
Flow, g/h	26.4	36.6	42.0	36.0	43.3	43.4	42.7	47.1	49.0	70.6	71.9	32.2	0.08	0.5
pH	7.7	7.2	7.4	7.4	7.4	7.2	6.7	6.6	6.4	6.8	7.2	7.7	0.09	<0.001