A total of 22 measurements of fat depth, taken along the 13th rib, 5-6th lumbar vertebra, 3-4th sacrum vertebra, and the
2nd, 2-3rd, 3rd, 3-4th, 4th. 4-5th stemebra of the breast bone, were taken on intact carcasses with a sharpened steel rule,
and related to the carcass composition of 18 Rasa Aragonesa lambs. The objective was to study the accuracy of these
different measurements for predicting carcass composition and possible value, in the process of carcass grading or
classification of ‘Temasco’ Aragdn lambs. Cold carcass weight (CCW) accounted for 74% and 40% of the total variation of
muscle weight and total carcass fat weight, respectively. The addition of 4 cm fat depth over the 13th rib from the left side
accounted for a further 13% of muscle weight, and the addition of 4 cm fat depth over the 5-6th lumbar vertebra from the
right side accounted for a further 29% of the variation of total carcass fat weight. Regarding different fat depots, CCW
accounted for 49% and 31% of the total variation of the intermuscular fat and kidney and pelvic fat, respectively.
However, CCW alone only accounted for 21% (NS) of the total variation of subcutaneous fat weight, but the addition of
4 cm fat depth over the 13th rib from the right side or the addition of 4 cm fat depth over the 5-6th lumbar vertebra from the
right side accounted for a further 47% of the subcutaneous fat variation. A comparison of the residual standard deviations
(RSD) of the two measurements indicated that the fat depth over the 5-6th lumbar vertebra was more accurate for predicting
subcutaneous fat. The highest precision, after CCW, for predicting intermuscular fat, was fat depth over the 13th rib from the
left side, which accounted for a further 18% of total variation of this fat depot. Prediction of carcass composition was
improved by the addition of fat depth measurements, assisting in the commercial classification of ‘Temasco’ Aragdn lambs.
