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Accuracy of dual energy X-ray absorptiometry (DXA), weight and P2 back fat to predict whole body and carcass composition in pigs within and across experiments

Suster, D., Leury, B.J., Ostrowska, E., Bulter, K.L., Kerton, D.J., Wark, J.D., Dunshea, F.R.
Livestock production science 2003 v.84 no.3 pp. 231-242
X-radiation, backfat, body composition, body weight, bone density, computer software, dual-energy X-ray absorptiometry, energy, livestock production, mineral content, nondestructive methods, swine
An Hologic QDR4500 dual energy X-ray absorptiometer (DXA) was used to measure body composition in 151 pigs ranging from 10 to 120 kg live weight. Large White×Landrace pigs of mixed sexes were selected from five different experiments to evaluate DXA accuracy within and across experiments. Values predicted by DXA including total tissue mass, fat tissue mass, lean tissue mass and bone mineral content, for the live animal, carcass and half carcass were evaluated by comparison with chemically-determined values. Relationships between chemically-determined values and measurements of weight and backfat at the P2 site were also evaluated. Chemically-determined values were strongly related with DXA-derived values, more so than with weight and P2 or a combination of both, particularly in the measurement of fat composition. In contrast to estimates derived from weight and P2, DXA-derived estimates remained accurate when between experiment variation was included. Incorporation of subregions into a whole body software analysis influenced DXA’s ability to predict fat tissue mass with the most accurate measurements achieved by placing the entire scan image in the left arm region of the regional analysis grid. These results demonstrate the efficacy of DXA as a nondestructive method for determining body composition in the live animal and carcass, and its greater accuracy than current routinely used methods.