Fat and Protein Supplementation of Calf-fed

Holstein steers have a greater maintenance energy requirement (Zinn and Borquez, 1993) and visceral organ mass (Istasse et al., 1990), and consume approximately 8% more feed than traditional beef steers (NRC, 1987; Fox et al., 1988). Because of their heavy mature weights, Holstein steers calves grow faster than beef steers at comparable weights (Thonney, 1987), capable to increasing their live weight by greater than 1%/d during the first 60 d in the feedlot (Smith et al., 1999; Zinn et. al., 1999; 2000)! Consequently, a primary constraint on growth during the early feedlot period is GI tract capacity. Thus, in order to fully express growth potential, receiving and growing diets for the calf-fed Holstein must be nutrient dense. Increasing diet nutrient density by modifying level and source of NDF (Ware and Zinn, 2004), grain processing, increasing the concentration and quality of protein (Zinn and Shen, 1998; Zinn et al., 2000), or addition of supplemental, are possible strategies to obtain better performance in the first days of feedlot to Holstein steers calves. This presentation we will focus primarily on fat, and to a lesser extent, protein supplementation.