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Title: Relationships among dual-energy X-ray absorptiometry (DXA), bioelectrical impedance (BIA), and ultrasound measurements of body composition of swine

Author
item Mitchell, Alva
item SCHOLZ, A - UNIV MUNICH GERMANY

Submitted to: Archives of Animal Breeding
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/18/2008
Publication Date: 2/1/2009
Citation: Mitchell, A.D., Scholz, A.M. 2009. Relationships among dual-energy X-ray absorptiometry (DXA), bioelectrical impedance (BIA), and ultrasound measurements of body composition of swine. Archives of Animal Breeding. 52(1):28-39.

Interpretive Summary: In recent years, a variety of approaches have been used to probe the animal in an attempt to gather information on live body composition. These include dual-energy X-ray absorptiometry (DXA), bioelectrical impedance (BIA) and real-time ultrasound. The purpose of this study was to provide a side-by-side comparison of these three techniques for measuring body composition (fat and lean content) of swine. For pigs measured at both 60 and 100 kg, there were high correlations between the BIA and ultrasound estimates of fat-free lean. This study also provided a side-by-side comparison of the BIA and ultrasound lean measurements relative to DXA and carcass composition. In both cases the correlation coefficients were higher for BIA compared to the ultrasound values. Also at 100 kg, DXA (fat and lean) and BIA (lean) correlated more highly with chemical analysis of the carcass than did ultrasound (lean). In conclusion, it appears that measurements of live body composition of pigs using DXA or BIA would be more reliable than ultrasound for predicting carcass composition.

Technical Abstract: In three separate studies (156 pigs total), DXA, BIA, and ultrasound were compared as methods for measuring live body composition of pigs at 60 and 100-110 kg BWt. DXA measured total body fat and lean content, BIA measurements of resistance (Rs) and reactance (Xc) were used to calculate total body lean mass, and ultrasound measurements of backfat (BF) depth and longissimus muscle area (LMA) was used to calculate total carcass lean mass. Following the 100-110 kg measurements the pigs were slaughtered and the half-carcass analyzed chemically for fat and water content. At 110 kg both DXA and ultrasound measurements were significantly correlated with the percentages of carcass fat and water, although correlations were higher for DXA. The correlations between DXA and BF measurements were higher at 110 kg than at 60 kg, whereas they were lower for DXA and LMA. For pigs measured at 100 kg there were high correlations between the DXA values and the BIA estimates for both FFM % and FFM kg; and the correlations between the BIA estimates of FFM and carcass fat and water content were similar to those for DXA and the carcass values. This study also provided a side-by-side comparison of the BIA and ultrasound lean measurements relative to DXA and carcass composition, in both cases the correlation coefficients were higher for BIA compared to the ultrasound values.