Relationships between chemical composition of meat from carcass cuts and the whole carcass in Iranian fat-tailed sheep as affected by breed and feeding level

To investigate the relationship between chemical composition of meat from the carcass cuts and the whole carcass, 48 nine-month-old randomly selected ram lambs of Ghezel and Mehraban (24 rams per breed) were used in a trial arranged as a 2 ´ 2 factorial experiment with two breeds and two feeding levels (high and low), in a completely randomized design. After 80 days, all animals were slaughtered and the right side of the carcass was cut into the leg, shoulder, back, neck, brisket and flap joints. Dry matter (DM), crude protein (CP), crude fat and ash were determined in meat from individual cuts and combined meat of all cuts (carcass meat). In general, average meat composition was not significantly affected by breed, feeding level and their interaction. Significant correlations were found between chemical composition of meat in most carcass cuts and carcass meat. Carcass DM in Ghezel sheep was highly correlated (P<0.001) with shoulder (r = 0.81) and back (r = 0.74) meat DM. In Mehraban sheep, back meat DM showed the highest correlation with carcass meat DM (r = 0.84, P<0.001). Back CP was significantly correlated with carcass meat CP in both breeds (r = 0.80, P<0.001). Carcass meat fat was significantly (P<0.001) correlated with back fat in both Ghezel (r = 0.76) and Mehraban (r = 0.84). In Ghezel, correlation coefficients of carcass meat ash and other parameters were generally small and non-significant. In Mehraban, carcass meat ash showed a small correlation with shoulder ash (r = 0.58, P<0.01) followed by back (r = 0.49, P<0.05) and brisket ash (r = 0.43, P<0.05). As a whole, chemical composition of the meat in the back joint showed the highest correlation coefficients with the corresponding parameters in the carcass, and may be used as a good predictor of carcass composition in these breeds. Regression analysis of the data indicated that percentages of fat and protein in back meat accounted for about 65% of total variation in carcass meat fat and protein.