Silage or hay based diets supplemented with different levels of grain for fattening cattle

Abstract

Beef steers of liveweight (LW) 277kg were offered a basal ration of hay, untreated silage, or enzyme-treated silage supplemented with a barley + lupin + mineral (67:30: 3) concentrate at 0.5, 1.0, and 1.5% of LW for a maximum of 120 days. The quality of silage was significantly (P<0.001) higher than hay (in vitro DMD: 673.0 v. 609.2 g/kg DM), primarily due to a shorter ungrazed growing period before harvest. The enzyme additive did not improve the quality of the silage compared with untreated silage, as indicated by pH, lactic acid, and in vitro dry matter digestibility. Intake of silage was significantly (P<0.001) higher than that of hay (4.10 v. 3.68 kg DM/day). Final LW and LW gain of cattle fed silage were significantly (P<0.001) higher than of those fed hay (370 v. 345 kg; 1.03 v. 0.61 kg/day). As the level of grain increased there was a significant (P<0.001) increase in daily LW gain across all diets (0.63, 0.94, and 1.10 kg/day at 0.5, 1.0, and 1.5%). At slaughter, carcass weight was significantly (P<0.001) higher for cattle fed silage-based diets (207 v. 194 kg). When cattle were fed a higher quality conserved forage (silage), less grain (1.5 v. 4.5 kg/day) was required to achieve similar LW than with more traditional, forage (hay) based diets.