Evaluation of directly and ultrasound measurements of muscle and back fat for prediction of Carcass traits of live animals in Afshari sheep

To evaluate capability of sonography for estimation of carcass traits of live animals in Afshari sheep a study was conducted using 97 male lambs of Afshari breeds. Lambs were at age of 11 month before slaughtering. Muscle thickness, loin muscle area and back fat thickness, between 12th and 13th ribs was measured using the ultrasound. Back fat and muscle thickness was also measured directly using a metal ruler in same area on the carcasses. Carcasses were stored at cold room for 24 hours and afterward were divided into two halves of left and right. The right side of carcasses dissected into neck, leg, thigh, tail and waste. Ultrasound measurement of longissimous muscle showed a high accuracy and highly correlated with carcass weight (0.84), arm(0.8), flank area (0.78) and thigh (0.74) muscles with bone, respectively. Ultrasound muscle depth and its direct measurement on carcass were highly correlated (0.87). But its correlation with weight of carcass components was less than those of muscle area. Correlation between fat depth measured by ultrasound and fat depth measured on the carcass was 0.7. Regression equations for prediction of carcass traits using ultrasound and carcass measurements were calculated. The results of this study showed that measurement of loin muscle area and back fat by ultrasound has relatively good accuracy and can be used for estimation of some carcass traits.