Effects of a grazing period on performance of finishing bulls: comparison with an indoor finishing system

Abstract

AbstractA 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 Fl 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.