Sub-samples were lyophilized, partially defatted and ground for further evaluation. In experiment II 15 Nellore heifers were allocated by body weight into three groups: 127±24.2 kg (low), 221±22.3 kg (medium) and 434±29.2 kg (high). Heifers were fed a diet consisting of 60% of corn silage and 40% of concentrate.