Published online by Cambridge University Press: 27 March 2009
This paper describes the chemical composition of dressed carcasses of Angus steers and relationships between chemical and dissected components of these carcasses. These cattle were grown from 300 to 440 kg at three different rates. The rates were: High (H, 0·8 kg/day), Low (L, 0·4 kg/day) and High-Maintenance (HM, 0·8 kg/day followed by a period during which body weight was maintained constant).
There were no significant differences between treatments in the regression equations for weight of water, protein or chemical fat against left side weight (half carcass). However, weight of ash was significantly greater in the HM group than in the H group. These results are similar to those obtained with dissection data on the right side of the same carcasses.
There were no significant differences between treatments for regression equations predicting dissected composition from chemical composition. The common regressions for each component are as follows:
log y (total side muscle) = 0·282 + 1·061 log × (protein) (Sν,× 3%), (i)
log y (total side bone) = 1·055 + 0·836 log × (ash) (Sν×) (ii)
log y (total side fat) = – 0·380 + 1·076 log × (chemical fat) (Sν,× 4%), (iii)
where all values of × and y are in grams.
Equations (i) and (ii) were used to predict the dissected composition of Angus steers from another experiment in which one group of cattle lost weight. Equation (i) gave useful predictions but equation (ii) did not.