Sheep carcass composition estimated from Longissimus thoracis et lumborum muscle volume measured by in vivo real-time ultrasonography

Abstract

The use of Longissimus thoracis et lumborum muscle (LM) volume measured in vivo by real-time ultrasonography (RTU) to estimate carcass composition was evaluated in 47 female sheep. Animals were scanned over six sites (7th, 9th, 11th and 13th thoracic vertebrae and 2nd and 4th lumbar vertebrae). After slaughter carcass weight (CW) and composition by dissection were determined. RTU volume measurements were calculated by multiplying the LM area at each site by the vertebra lengths. Equivalent measurements to those taken in vivo were obtained on the carcass using a digital camera and image analysis. The correlation between LM volume measured by RTU and in the carcass was high for all scans. LM volume was better in predicting carcass muscle than carcass fat. Lower determination coefficients were obtained between LM volume and carcass tissues expressed in % of CW. The best estimates of carcass tissues weights and proportions were obtained using the LM volume between the 2nd and the 4th lumbar vertebrae for all tissues. Multiple regression equations were fitted using live weight (LW) and LM volume to predict carcass composition. For all tissues, the best fit was obtained with two, three or four independent variables and the stepwise procedure was consistent in selecting LW to establish the prediction equations. Weights and proportions of muscle, subcutaneous fat, intermuscular fat and total fat were accurately predicted. These results indicate that Longissimus thoracis et lumborum muscle volume measured in vivo by RTU can be used to predict sheep carcass composition (muscle and fat).

Real-time ultrasound (RTU) imaging methods for quality control of meats

“…(2006) Aloka 500V; 5 and 7.5 MHz Predicting carcass composition Hopkins et al . (2007) Honda HS-1201; 5 MHz Accuracy of RTU measurements and predicting carcass composition Silva et al . (2007a) Aloka 500V; 7.5 MHz Predicting carcass composition Leeds et al .…”

“…A large number of studies (McEwan et al ., 1989;Silva et al ., 2006a;Teixeira et al ., 2006;Hopkins et al ., 2007;Silva et al ., 2007a;Leeds et al ., 2008;Teixeira et al ., 2008;Thériault et al ., 2009;Emenheiser et al ., 2010;Orman et al ., 2010) have found a significant correlation ( r > 0.6; P < 0.01) between both fat and muscle RTU measurements and the corresponding carcass measurements in those regions. The placement of the probe at reference points must be correct, since SFD and LTL muscles vary significantly over short distances either cranio-caudally (Delfa et al ., 1991;Silva et al ., 2007a) or medium-laterally (Simm, 1983;Korn et al ., 2005). In addition, anatomical distortions arising from the position of the animals and skin flexibility may also contribute to discrepancies between RTU and carcass measurements (Thwaites, 1984;Leeds et al ., 2008).…”

“…This is undoubtedly a strong justification for recording ultrasonic images for later analysis. Other factors that justify the recording of images and their subsequent analysis are the shorter time required to evaluate the animals (Glasbey et al ., 1996;Silva et al ., 2006a); the possibility of obtaining several measurements from the same image including irregular areas (Silva et al ., 2007a); and improvements in repeatability, since the interpretation of the images is more important than its acquisition (McLaren et al ., 1991).…”

Estimation of light lamb carcass composition by in vivo real-time ultrasonography at four anatomical locations1

“…The BW variable is the most important measurement for predicting muscle weight (Shelton et al, 1977;Jones et al, 1982;Kempster et al, 1982a;Fortin and Shrestha, 1986;Silva et al, 2007), and the inclusion of ultrasound measurements normally provides only a little improvement in the accuracy of the prediction (Leymaster et al, 1985). However, the present results showed that narrow ranges of BW did not offer much as a predictor of the carcass composition of Ternasco lambs because many factors affect the rate and onset of fattening in meat animals, in agreement with , Berg et al (1996), and Puntilla (1986).…”

Models predict the proportion of bone, muscle, and fat in ewe lamb carcasses from in vivo measurements of the 9th to 11th rib section and of the 12th rib

“…The use of ultrasound in determining subcutaneous fat thickness and ribeye area would represent an excellent tool for the generation of models that estimate muscle-tofat ratios prior to slaughter, which would allow producers to sell animals with pre-defined carcass profiles (SILVA et al, 2007).…”