The nutritive value of maize residues, presented in three forms to growing Simmentaler steers (250 ± 31 kg), was evaluated by means of a growth and digestion study. The three forms of maize residues evaluated were: (i) selected material which implied free choice selection of approximately 33% of the residues presented (Treatment 1), (ii) material remaining after selection, which was milled (Treatment 2) and (iii) material remaining after selection which was thermo-ammoniated and milled (Treatment 3). Residues were supplemented with crude protein (CP) and phosphorus. Steers selected material with an in vitro dry matter digestibility (IVDMD) of 67,9 and 71,2%, leaving non-selected remains with an IVDMD of 51,8 and 51,5% during growth and digestion trials, respectively. The IVDMD values for ammoniated remains during growth and digestion trials were 59,7 and 59,2% respectively. These IVDMD values were determined for maize residue fractions without supplementation. Steers fed in Treatment 1 showed a mean mass increase of 0,65 ± 0,19 kg/d compared to 0,37 ± 0,10 kg/d (P < 0,05) for steers in Treatment 2. Mean dry matter (DM) intake for steers in Treatments 1 and 2 was 2,67 and 2,08% of body mass, respectively. Steers fed on ammoniated remains plus oilcake as protein supplement (Treatment 3) showed a mean mass increase of 0,67 ± 0,21 kg/d, which was higher (P < 0,05) than that of steers in Treatment 2. DM intake was 2,06% of body mass. Apparent DM digestibility for selected residues plus a CP supplement (Treatment 1) was 69,2 ± 3,0%.
