THE PREDICTION OF SALEABLE MEAT YIELD IN LAMB CARCASSES

A total of 281 lamb carcasses covering three weight groups (18-22.9, 2 3-25.9 and 26-30 kg) and fatness (< 3 mm, 3-5 mm and > 5 mm) were used to determine the usefulness of several carcass measurements for predi cting saleable meat yield. Carcasses were measured for fat and muscle depth, 3-4 cm from the mid-line between the 10th and 11th ribs, 12th a nd 13th ribs and immediately adjacent to the 13th rib using a Hennesse y Grading Probe. This technique also determined total tissue depth at 11 cm from the mid-line between the 10th and 11th and 12th and 13th ri bs. The depth of tissues over the 12th rib, II cm from the mid-line wa s measured with a ruler. Carcasses were also visually assessed for mus cle development (conformation score) on a 5-point scale (1 = thinly fl eshed; 5 = thickly fleshed). All carcasses were fabricated into primal cuts which were trimmed to 5 mm of fat and deboned to provide an esti mate of saleable meat yield. Ewe lamb carcasses had a higher proportio n of kidney fat than wethers in all weight and fat groups (which range d from 2.6 to 17.9 g kg(-1) carcass weight). Saleable meat yield decre ased as carcasses became fatter, whereas weight group had little influ ence on saleable meat yield within a fat group. Ewe lamb carcasses had lower saleable meat yields than wether lamb carcasses, mainly because of their higher amounts of kidney fat. A ruler measurement of tissue depth over the 12th rib combined with carcass conformation score provi ded the most precise prediction (R(2) = 0.61; RSD 17.1) of saleable me at yield. It was concluded that a simple manual system based on these two measurements provided an adequate prediction of saleable meat yiel d. The accuracy of the procedure would be increased by excluding kidne y fat from carcass weight for the prediction of saleable meat yield.