"Effects of Matching Protein to Requirements on Performance and Waste M" by Galen E. Erickson, Terry J. Klopfenstein et al.
Four experiments were conducted, two with calves in the winter/spring and two with yearlings during the summer, to evaluate the effects of decreasing protein levels on nutrient balance in the feedlot. The control diet was formulated for 13.5 percent protein; the experimental diets were formulated using the 1996 NRC model to predict protein requirements. Nutrient balances for organic matter (OM) and nitrogen (N) were measured. Nitrogen intake and subsequent excretion were decreased with steers fed the experimental treatment. During the summer more N was removed from pens on the experimental treatment since OM excretion was greater which led to decreased N volatilization. N losses were lower in the winter/spring feeding periods when expressed as percentage volatilized.