Thirty spring born Hereford bulls, 8-9 months oid, with average body weight of 235 kg, were fed with five different rations of rapeseed soap stock, molasses, and red dover hay, at Carillanca Exp. Sta. (INIA, Temuco). Rapeseed soap stock and molasses were included, respectively, at 0 and 25% (T I), 2 and 18.75% (T II), 4 and 12.5% (T III), 6 and 6.25% (T IV), and 8 and 0% (TV), on a D.M. basis. Red dover hay was given at 50, 54.25, 58.5, 62.15, and 67%, respectiveiy. Besides, oat grain, rapeseed meal, and minerals were offered at 15, 7.5, and 2.5%, respectively. The rations were isoproteic and isoenergetic. A randomized complete block design was used. Daily gains were close to 1 kg (P > 0.05). D.M. intakes were 9a, 8.7a, 8.7a, 8.1b, and 7.7c (P < 0.05) for the five rations respectively. The efficiencies of feed conversion were 8.8a, 8.0b, 7.8b, 8.0b, and 7.9b kg D.M./kg L.W., respectively. The in vivo digestibiliy of the rations was analized.