Carcass and live measurements of 203 pigs representing seven genetic popula
tions and four target live weights (100, 114, 128, and 152 kg) were used to
evaluate alternative measures of carcass composition. Measures of carcass
lean (fat tissue-free lean, FFLM; lipid-free soft tissue, LFSTIS; and disse
cted lean in the four lean cuts, DL), fat (total carcass fat tissue, TOFAT)
, and lipid mass (soft tissue lipid, STLIP) were evaluated. Overall, LFSTIS
was 22.8% greater than FFLM (47.8 vs 38.9 kg) and TOFAT was 30% greater th
an STLIP (38.5 vs 29.6 kg). The allometric growth coefficients relative to
carcass weight were different for the measures: b = 0.776, 0.828, 0.794, 1.
37, and 1.49 for FFLM, LFSTIS, DL, TOFAT, and STLIP, respectively. At 90 kg
carcass weight, the predicted growth of FFLM, LFSTIS, TOFAT, and STLIP was
0.314, 0.420, 0.553, and 0.446 kg/kg increase in carcass weight. The diffe
rence between FFLM and LFSTIS, representing nonlipid components of the carc
ass fat tissue, was greater for barrows than for gilts (9.2 vs 8.6 kg). Lip
id-free soft tissue mass was predicted more accurately from carcass or live
animal measurements than FFLM with smaller relative RSD (4.6 vs 6.5% of th
eir mean values). The alternative measures of carcass composition were eval
uated as predictors of empty body protein (MTPRO) and lipid (MTLIP) mass. E
mpty body protein was predicted with similar accuracy (R-2 = 0.74 to 0.81)
from either DL, FFLM, LFSTIS, or ribbed carcass measurements. Empty body li
pid was predicted more accurately from TOFAT (R-2 = 0.92) or STLIP (R-2 = 0
.93) than ribbed carcass measurements (R-2 = 0.88). Although the alternativ
e measures of lean mass (LFSTIS vs FFLM) and lipid mass (TOFAT vs STLIP) we
re highly related to each other (r = 0.93 to 0.98), they had different rela
tive growth rates (allometric coefficients) and thus cannot be predicted as
linear functions of the similar alternative variable without significant w
eight group biases. From the 100- to 152-kg target weight groups, gilts gai
ned 12.9% greater FFLM and 12.1% greater MTPRO but only 4.4% greater LFSTIS
than barrows. Fat-free lean mass is more precise as a measure of muscle gr
owth and as a predictor of lysine requirements. Lipid-free soft tissue can
be obtained more quickly and predicted more accurately from carcass or live
animal measurements.