Diets were formulated to exceed MP requirements
using the NRC (1996) model. Monensin (33 mg/kg, Rumensin;
Elanco Animal Health, Greenfield, IN), tylosin
(8.7 mg/kg, Tylan; Elanco Animal Health) and vitamins
and minerals to meet or exceed NRC (1996) requirements
were incorporated into a supplement premix. Steers were
fed for a total of 78 d. For Exp. 1 and 2, diets were mixed
3 times each week and stored indoors in a feed cart. Cleanout
of the mixer unit was monitored to ensure that cross contamination
of diets was minimized. The SFC (bulk
density of 350 g/L) was purchased 3 or 4 times per week
from a feedlot. GLY was purchased from Westway Feed
Products (Hereford, TX) as needed.