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This Article Full Text (PDF) All Versions of this Article: jas.2008-1285v1 87/4/1455    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 Ripoll, G. Articles by Teixeira, A. Search for Related Content PubMed PubMed Citation Articles by Ripoll, G. Articles by Teixeira, A.

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

G. Ripoll, M. Joy, J. Alvarez-Rodriguez, A. Sanz and A. Teixeira

Unidad de Tecnología en Producción Animal. CITA. Avda. Montañana, 930. ZIP code 50059. Zaragoza (Spain) Escola Superior Agrária de Bragança. Centro Investigação de Montanha. P.O. box 172. ZIP code 5301-855. Bragança, Portugal

gripoll{at}aragon.es

Abstract

The objectives of this study were to study the relationship between in vivo ultrasound measurements and cold carcass measurements at 4 anatomical points of the backbone, and to establish regression equations to estimate carcass composition within the cold carcass weight range for Ternasco lambs (8-12.5 kg, B.O.E., 2006) using ultrasonic measurements taken at a single location. Measurements of subcutaneous fat and skin thickness, and muscle depth and width were taken over the 10^th-11^th, 12^th-13^th thoracic vertebrae and 1^st-2^nd and 3^rd-4^th lumbar vertebrae. These measurements were taken at 2 and 4 cm from the nearest end of the longissimus dorsi to the backbone and at 1/3 of the longissimus dorsi width with the probe perpendicular and parallel to the backbone. The left sides of the carcasses were dissected into muscle, fat and bone. BW (22.6 kg) and cold carcass weight (10.8 kg) were representative of Ternasco light lambs. Muscle depth measured at 2 cm, 4 cm and 1/3 had remained regular with slight ups and downs along the spine. All of the pairs of in vivo ultrasound and cold carcass measurements were significantly different (P<0.05) and had small correlations. All of the ultrasound measurements of muscle depth at any location or distance to the backbone were lower than their equivalent cold carcass measurements, with differences from 0.8 to 5.9 mm. Differences between ultrasound fat thickness+interface (US_FDGI) and cold carcass fat thickness were lower than differences between ultrasound fat thickness and cold carcass fat thickness, ranging from -0.9 to -1.0 mm for the former and from -2.1 to -0.5 mm in the latter case. The small differences in absolute values between US_FDGI and cold carcass fat thickness suggest that US_FDGI is the best measure to know the real fatness level of the lambs. The best prediction equations for muscle, bone and fat were developed with in vivo ultrasound data measured at 1-2L perpendicularly to backbone, but they had limited predictive value. To predict muscle content of carcass, BW and muscle depth were included and they explained 59% of variation. 51% of total fat was predicted by BW and fat thickness while only 17% of variation of bone was predicted by 2 fat- related variables. BW of lambs was an important predictor to improve regression equations but ultrasounds were the most important variables when a narrow range of BW was used.

Key Words: carcass composition • fat thickness • muscle depth • prediction • regression • ultrasounds