EFFECT OF DIETARY-PROTEIN LEVEL ON PERFORMANCE OF EARLY-WEANED DOUBLE-MUSCLED CALVES

The effect of the protein content of the concentrate on the performanc e during a 20-week rearing period was investigated, using thirty-two m ale and thirty-seven female newborn double-muscled calves, belonging t o the Belgian White-Blue breed. A restricted milk diet was fed. Weanin g occurred when daily concentrate consumption reached 0.5 kg. The crud e protein content of the concentrate amounted to 15% (LP) or 18% (HP) on an as-fed basis. Concentrate and grasshay were fed from a 2-week ag e onward. Daily concentrate intake was limited to a maximum of 3 kg, w hile hay was freely available. Weaning occurred at a similar live weig ht (LP: 80.1 vs. HP: 80.7 kg) and after a similar number of experiment al days (LP: 60.5 vs. HP: 57.4 days). Total dry matter (DM) intake dur ing the entire period (LP: 260.2 vs. HP: 267.2 kg) was not affected by dietary crude protein. Liveweight gain after weaning (LP: 0.98 vs. HP : 1.05 kg/d) and during the entire rearing period (LP: 0.78 vs. HP: 0. 84 kg/d) was increased when the HP concentrate was fed. DM and net ene rgy were more efficiently used in calves fed the HP concentrate, while protein was less efficiently converted at the higher dietary protein level. Higher dietary protein also increased serum urea concentration. Based on an increased Liveweight gain and a better conversion of DM a nd net energy, on the one hand, and a reduced protein efficiency and a higher serum urea concentration on the other hand, it is concluded th at a dietary level of 200 g crude protein (CP) or 114 g true protein d igested in the small intestine (DVE) per kg DM is near the optimum in early-weaned double-muscled calves. It improved daily liveweight gain and feed conversion, compared to 167 g CP or 100 g DVE per kg DM. Thes e results give evidence that the optimal dietary protein level in earl y-weaned double-muscled calves seems to be higher than in non-double-m uscled calves. (C) 1998 Elsevier Science B.V.