Effect of slaughter weight and plane of feeding on growth, utilisation of feed and carcass quality of young bulls

Andersen, H.R.

Beretning fra Statens Husdyrbrugs Forsoeg 430: 124


Accession: 000355930

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Danish Red cattle reared together to 73 days of age, in 28 groups of 6, were fed to appetite or had 85, 70 or 55% of that in Scandinavian feed units (FU) and on each ration were killed at 180 kg liveweight or at 6 intervals of 60 kg to 540 kg. On each plane of nutrition greatest daily gain was at about 270 kg liveweight. On the higher levels of nutrition percentage carcass yield increased with liveweight. The yield also increased with feeding rate. The greatest daily gain in carcass weight was at about 300 kg liveweight. With feeding to appetite greatest growth of bone was before 200 kg liveweight, of lean at 275 kg and of fat at 480 kg. Ratio of lean to bone increased with weight. Restriction of intake reduced increase of fat more than increase of lean or bone, and difference was greater at heavier slaughter weight. On decreasing rates of feeding greatest daily gain of fat was at 480, 450, 375 and 300 kg liveweight. With killing at 200 kg ratio of lean to bone fell as ration decreased. The fall was proportionately less as slaughter weight increased because gain of bone decreased more than gain of lean. Estimated total requirement of FU from 95 kg to the end was least on 85% of intake to appetite. Difference among groups increased with liveweight. Requirement for gain also was least on restriction to 85%, and generally increased with liveweight. In carcass, proportions of lean and bone decreased and of fat increased with liveweight. Restriction of feed increased bone and decreased fat, and the effect was mainly at heavier slaughter weights. At low weights proportion of lean was greater with higher feeding rate, but above 150 kg carcass weight the reverse was true. At low weights the effect of plane of nutrition on carcass quality was small. Growth coefficients of tissues at different weights and of different parts are shown. Flank developed more and loin and rump less as liveweight increased. At equal weight of muscle in the carcass relative proportions of total muscle and flank, brisket and longissimus dorsi were greater on higher planes of nutrition, and proportion as neck was less. At equal carcass weight flank, rib, brisket, flat ribs and foreshank were less and forerib, neck and shoulder were more with restricted feeding, but proportions of loin and rump were little affected. Composition as lean, bone and fat with different planes of nutrition is shown. Subjective evaluation of live cattle and carcass favoured the higher planes of nutrition and on a high plane favoured heavier weights.