HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text (PDF) All Versions of this Article: jas.2008-1002v1 87/5/1801    most recent Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Thériault, M. Articles by Castonguay, F.W. Search for Related Content PubMed PubMed Citation Articles by Thériault, M. Articles by Castonguay, F.W.

Accuracy of real-time ultrasound measurements of total tissue, fat and muscle depths at different measuring sites in lamb

M. Thériault^*,, C. Pomar^* and F.W. Castonguay^*,

^* Dairy and Swine Research and Development Centre, Agriculture and Agri-Food Canada, Sherbrooke, QC, Canada, J1M 1Z3 Département des sciences animales, Université Laval, Québec, QC, Canada, G1K 7P4

francois.castonguay{at}san.ulaval.ca

Abstract

Accuracy of live ultrasound measurements to evaluate the total tissue depth (GR), as well as fat and loin muscle depths at different scanning sites was studied in 96 purebred Suffolk and Dorset lambs of both sex harvested between 36 and 54 kg. Before harvest, 7 real-time ultrasound measurements were taken on lambs: fat and loin muscle depths between the 12th and 13th ribs (transverse) and between the 3rd and 4th lumbar vertebrae (transverse and longitudinal), and total tissue depth (GR). After harvest, the measurements equivalent to ultrasound measurements were taken on digitized images of the cuts on the left half carcass of each lamb. Ultrasound GR and fat depth measurements were closely correlated with the corresponding carcass measurements (0.76 < r < 0.81). Ultrasound GR measurement exhibited a large error of central tendency (ECT), but the level of error due to the disturbance (ED) was comparable to fat depth measurements (ED = 8.5%, RSD = 2.24 mm; Cve = 9.5%). Ultrasound fat depth measurements were more accurate between the 12th and 13th ribs (error due to regression (ER) = 1.20; ED = 0.82) than between the 3rd and 4th lumbar vertebrae (ER = 5.58 and 5.4; ED = 1.10 and 0.93, transverse and longitudinal, respectively), owing mainly to image interpretation errors in the lumbar region. Measurements of loin muscle depth demonstrated low variability in the population under study (SD = 2.6 mm), and these ultrasound measurements showed low correlation with the corresponding carcass measurements (0.34 < r < 0.43). The results of this study demonstrated that ultrasound measurements were more accurate for evaluating fat depth and the GR measurements than for estimating loin muscle depths. Ultrasound GR measurement is a promising measurement, especially where carcass grading systems are based on this carcass measurement.

Key Words: Fat Depth • GR Measurement • Lamb • Live Measurement • Loin Muscle Depth • Ultrasound