EFFECTS OF A GRAZING PERIOD ON PERFORMANCE OF FINISHING BULLS - COMPARISON WITH AN INDOOR FINISHING SYSTEM

A comparison was made between two different finishing systems with Belgian Blue bulls. Two groups of bulls were grazed during an initial 140-day period and then finished indoors with concentrates. There were two stocking rates during the grazing period: a medium at six bulls per ha (MGFI) and a high at eight bulls per ha (HGFI). A third group of bulls was finished indoors on a concentrate diet during the whole finishing period (FI). The experiment was repeated over 2 years consecutively. The pasture which was grazed at the medium stocking rate was characterized by a higher sward height (P < 0.01), more refusals (P < 0.001), less Lolium perenne (P < 0.05) and more Trifolium repens (P < 0.05) than that grazed at eight bulls per ha. The live-weight gain was 1.15 kg/day during the grazing period for the MGFI bulls and 1.00 kg/day when they were taken indoors. The increase in stocking rate reduced the gain at grass (1.00 kg/day, P < 0.001) and improved the gain indoors (1.24 v. 1.01 kg/day, P < 0.001). In the groups which were initially grazed when compared with the indoor system, the fattening period was longer (236.0 and 241.0 v. 186.9 days, P < 0.01) and the live-weight gain lower (1.11 and 1.10 v. 1.44 kg/day, P < 0.001 for MGFI, HGFI and FI respectively). The dressing proportion was greater also (P < 0.05), and there were higher concentrations of muscles (P < 0.05) and bones (P < 0.05) in the carcass of the bulls which were grazed initially. With these bulls, the lean meat was darker (P < 0.05) and lost more water although there were no effects on the myoglobin content or on shear force. The net profit was in favour of the groups which were grazed.