Performance, Carcass Traits, and Nutrient Excretion of Beef Feedlot Cattle Fed a Corn Gluten Feed Diet1

Forty-eight crossbred steer calves (initial BW = 272 kg) blocked by BW were randomly assigned to eight pens and were fed either a 12.9% CP high concentrate diet with 15% corn silage (CS), 0.51% urea, and 0.30% P or a 13.4% CP high concentrate diet with 45 to 50% corn gluten feed (CG) and 0.60% P for the growing-finishing period to compare growth performance and carcass traits and to determine nutrient excretion. Steers were housed in outside pens with shelter and constant access to water. Steer BW were taken at the initiation, at 28-d intervals, and at the completion of the 186-d trial. Steers were harvested at approximately 540 kg, and carcass data were collected after a 24-h chill. Manure was collected and sampled from each pen for a 3-d period (d 146 to 148 of the trial) and pooled by treatment for analysis. Overall, CG-fed steers tended (P=0.11) to have higher daily gain. Dry matter intake was greater (P<0.05) for steers fed the CG diet during the last 56 d of the trial, which contributed to a poorer (P<0.05) feed conversion during this period. Fat thickness; percentage of kidney, pelvic, and heart fat (%KPH); and longissimus area (REA) were not different between treatments. Manure total N was not affected by dietary treatment, and total P excretion was 85% greater (P<0.05) when steers were fed the CG diet compared with the CS diet. Water-soluble P and organic P were also greater (P<0.05) for steers fed the CG treatment compared with the CS treatment. Manure ammonium N was 42% greater (P<0.05) from the CG treatment when compared with the CS treatment. Feedlot diets supplemented with CG dramatically exceed P requirements and can lead to P accumulation in manure, which must be carefully managed to minimize an adverse impact on the environment.