Carcasses of 156 pigs (78 gilts, 78 barrows) slaughtered at 200 lb live weight, were probed by introscope at six positions in line with the last rib. Backfat was measured directly and muscle depth was obtained as the difference between total probed depth from skin to rib and backfat depth. The various measurements were used to predict eye-muscle area measured on the exposed cross-section of the longissimus dorsi cut at the level of the last rib.

Depth of muscle at 7·5 cm and depth of fat at 10 cm were the best predictive measurements for both barrows and gilts, although muscle at 4·5 cm in gilts and at 10 cm in barrows were of equivalent value to muscle at 7·5 cm. The correlation between observed and predicted values of eye-muscle area was 0·8. The accuracy of these predictions compared favourably with those of carcass lean percentage from maximum depth of backfat at shoulder, minimum depth of fat at loin and fat depth at ‘C’.