The effect of body-weight loss on the composition of Brahman cross and Africander cross steers: II. Dissected components of the dressed carcass

Abstract

SummaryComparative slaughter was used to assess the effects of body-weight loss on Brahman cross (BX) and Africander cross (AX) steers of the F3generation with respect to gross dissected carcass composition and the distribution of these components over the dressed carcass. Animals were slaughtered at design body weights of 325, 341, 358, 374 and 390 kg, some while during positive body-weight growth (Group A), and others during weight loss from 390 kg at a rate of approximately 0–5 kg/day (Group B).Gross composition was similar in the two breeds, irrespective of the body-weight loss treatment. Body-weight loss resulted in muscle and fat approximately reversing the path of development, while bone and fascia and tendon remained approximately constant. No evidence of proportionally early loss of fat and later loss of muscle was found. Of the fat components, kidney and channel fat showed the highest relative loss. The distribution of muscle was different between the breeds, the most statistically significant differences being that AX had heavier muscles around the spinal column and lighter shin muscles, at the same total muscle weight. Bone weight distribution differences also occurred, with AX tending to have lighter leg bones, at the same total bono weight. A breed difference in intermuscular fat distribution meant that the AX animals were earlier developing in the forequarter and later developing in the hind quarter in respect to its intermuscular fat, than the BX animals.Body-weight loss affected muscle-weight distribution, the most marked effect being that the relative proportion of abdominal muscles fell during body-weight loss. Boneweight distribution was affected to a minor extent, the effects mainly being in the leg bones rather than the axial skeleton. The distribution of neither fascia and tendons nor subcutaneous fat was affected by the body-weight loss treatment, but the distribution of intermuscular fat was affected.