Use of dorsal and caudal real-time ultrasonic measurements in predictingin vivo carcass composition of fat-tail Barbarine lambs

Abstract

The study was carried out on 21 fat tailed Barbarine lambs in the aim to predict in vivo carcass composition (body fat and muscle) from body weight (BW) or carcass weight (CW) and ultrasonic measurements taken on dorsal and caudal sites. In vivo measurements included subcutaneous fat thickness (FTh), longissimus dorsi muscle depth (MTh), muscle area (MAr) and muscle circumference (MCir) between the 12th and 13th ribs and the fat tail thickness (FTTV) using real time ultrasound “falco vet” with a 3.5-MHz probe. The same measurements were also taken on carcasses. The carcasses were weighted (CW), then dissected on bone, fat and muscle. Predicting models of muscle and fat content were established using BW and in vivo measurements or CW and carcass ultrasonic measurements. The BW was the most important in vivo indicator to predict carcass composition (54 and 70% for muscle and fat, respectively). These accuracies increased by 11 and 8%, respectively with CW. The in vivo prediction of muscle weight was improved by FTV rather than FTTV (5 vs. 0%). The muscle optimal prediction accuracy (75%) was attended by whole carcass ultrasonic measurements in dorsal and tail sites added to CW. The carcass fat was estimated with the same accuracy (72%) when FTh or FTTh was added to BW. A higher in vivo fat prediction accuracy was obtained when The FTTh was used as independent variable in addition to BW, MAV, MCV and MDV in the multiple regression equations in comparison with the same predicting model containing FTh (79 vs. 77%). The fat optimal prediction accuracy (92%) was reached by whole carcass ultrasonic measurements in dorsal and tail sites added to CW.