Ultrasonic estimates of fat thickness and Longissimus dorsi muscle depth for predicting carcass composition of live Aragon lambs

Abstract

Six ultrasonic fat and muscle depth measurements, taken on the left and the right side of the fourth lumbar vertebra and third stemebra of the breast bone, were related to carcass composition to determine the accuracy of these measurements for predicting carcass compositon of live Aragdn lambs (Temasco) . Live weight alone accounted for 21, 19,26, 18 and 47% of total variation of muscle, bone plus remainder, total fat, and subcutaneous and intermuscular fat, respectively. Addition of ultrasonic fat depth measurement on the right side of the lumbar region accounted for a further 18,31,33 and 36% of muscle, bone plus remainder, total carcass fat and subcutaneous fat, respectively. Addition of the same measurement taken on the left side accounted for a further 15% of intermuscular fat. Live weight alone accounted for only 4% of the total variation of kidney and pelvic fat, but the addition of ultrasonic fat depth measurement on breast bone accounted for a further 26% of the variation of this fat depot. The accuracy of prediction of carcass composition on live animals could be improved by the addition of ultrasonic fat measurements.

In vivo estimation of lamb carcass composition by real-time ultrasonography

“…In fact, 96% of the variation in the total amount of muscle was accounted for by live weight, and none of the ultrasound measurements admitted as independent variables in the model, as previously found by Teixeira and Delfa (1997) (R 2 = 0.94). Also, Delfa et al (1995) found similar results for muscle prediction, however, they obtained smaller determination coefficients (R 2 = 0.21; P < 0.01). For muscle content live weight alone accounted for 92% of the variation of total weight of carcass bone.…”

“…They found an improvement in the precision of the prediction when they used live weight in a multiple regression with the fat thickness measurement, using a 5 MHz probe, agreeing with the work of Fernández et al (1998). In the work of Delfa et al (1995), live weight accounts for only 18% of the total variation of the carcass subcutaneous fat weight. When fat thickness measured at the 4th lumbar vertebra was included in the model the variation explained was higher (R 2 = 0.54), however, this value is less than the value obtained in the present work.…”

“…the first variable used in the regression model, explaining, by itself, 82% of the variation of the weight of intermuscular fat, a value higher than that obtained by Delfa et al (1995) (R 2 = 0.47), Delfa et al (1996) (R 2 = 0.47) and Teixeira and Delfa (1997) (R 2 = 0.50). The values obtained in our work were more accurate than those observed by Teixeira and Delfa (1997) (R 2 = 0.70) and Delfa et al (1995) (R 2 = 0.60), although in this last paper, the predictor used was the fat thickness measured at the 4th lumbar vertebra.…”

“…For muscle content live weight alone accounted for 92% of the variation of total weight of carcass bone. Nevertheless, Delfa et al (1995) found that live weight only accounted for 19% of the variation of the bone weight. The inclusion of ultrasound fat thickness measurement at the 4th lumbar vertebra allowed a significant (P < 0.05) improvement in the accuracy of the prediction, providing an increase in the determination coefficient of 31% and a decrease in RSD of 20.4%.…”

“…Nevertheless, the potential use of this technique to predict the weight of the different tissues of the carcass has been demonstrated by several authors (Delfa, Teixeira, Gonzalez, & Blasco, 1995Fernández et al, 1998;Hopkins, 1990;Kempster, Arnall, Alliston, & Barker, 1982;Mendizabal et al, 2003;Teixeira & Delfa, 1997).…”