Information relating to the carcass composition of grass-fattened beef cattle in the UK is not only limited in extent, but is also frequently uni-dimensional, in that the quantitative changes in carcass composition with time cannot be readily assessed. Furthermore, the methods used in selecting animals for slaughter (the visual appraisal of condition) introduces a source of non-random variation that cannot be removed with statistical confidence.

The primary objective of the analysis reported here, therefore, was to evaluate the effects of time on carcass composition and thereby provide information upon which objective production strategies could be based.

48 fattening steers and heifers (16-19 months old and 355 kg liveweight) of two contrasting breed types (Charolais x Hereford x Friesian and Hereford x Friesian) were summer grazed at a stocking rate of 5 animals per hectare. The animals were randomly allocated (at the start of the grazing season) to three slaughter points covering a 12 week period from early July to early October. The commercial saleable meat yield of the left side of each animal was measured together with compositional data from rib sample joints.