Animals, Husbandry, and Diet
The Kansas State University Institutional Animal
Care and Use Committee approved all surgical, postoperative,
experimental, and animal husbandry procedures.
Six crossbred (predominately Hereford and Angus;
initial BW = 207 ± 7.8 kg) steers were surgically fitted
with double L-shaped (Streeter et al., 1991) duodenal
(approximately 10 cm distal to the pylorus and proximal
to the common pancreatic-bile duct) and ileal (approximately
10 cm proximal to the ileocecal junction) cannulas
30 d before experimentation. Cattle were tethered
in tie-stalls (1.7 by 1.2 m) in a temperature-controlled
room (20°C) under 16 h of light (0500 to 2100 h) and
8 h dark. Before and during experimentation, cattle
were fed a common soybean hull-based diet (Table 1)
twice daily (at 0700 and 1900 h) and allowed ad libitum
access to fresh water. The diet was formulated to
provide adequate ruminally available N and to meet or
exceed requirements for vitamins and minerals (NRC,
1996). The diet was specifically designed to contain little
starch, and it also was designed to provide only modest
amounts of RUP so that MP supply would be moderate