and feed additives were contained in a ground corn and
wheat-middling based pelleted supplement mixed at the
Oklahoma State University Feed Mill.
Ration samples were collected once/week, dried in a
forced air oven for 48 h at 60°C to determine DM. Average
DM was calculated for the feeding period, and actual DMI
consumption was calculated at the end of the study by
dividing total kilograms of feed consumed by total head
days of a pen. Ration samples were composited gravimetrically
and analyzed at a commercial lab (Servi-Tech,
Inc. Dodge City, KS) for nutrient composition. Samples
were assayed for monensin concentration (Covance
Labs, Greenfield, IN) and ZH (Merck Pharmaceutical
Laboratory; Lawrence, KS). Orts were obtained on each
weigh day and during inclement weather events. Dry matter
was obtained, and feed was removed from total feed
delivered for accurate DMI calculation. All performance
calculations are the same as those described in Maxwell
et al. (2014). Estimated carcass gain and feed efficiency
were calculated by estimating dressing percentage using
the equation described by Parr et al. (2011; predicted
dress = [0.03 × 4% shrunk BW, kg] + 46.742). The equations
described by Zinn (1992) and NRC (2000) were
used to determine dietary NEm and NEg.