Efficacy of deuterium oxide to estimate body composition of growing swine.

An experiment involving 73 pigs was conducted to evaluate the efficacy of the deuterium oxide (D2O) dilution procedure for in vivo estimation of body composition in swine. Pigs were infused with known quantities of D2O at 6.4 and 18 kg and then at approximately 18 kg increments to 145 kg body weight. Postinfusion blood D2O concentrations were partitioned into early- and total-equilibrating pools. Results from D2O analyses were compared with empty (ingesta-free) and total body water values obtained from chemical analysis of the ground animals. Both early- and total-equilibrating D2O pools seemed to be good estimators of empty body weight. Total body D2O space was similar to total body water at 6.4 kg, but consistently overestimated body water (averaged 20%) as the pigs attained heavier weights. Early- or total-body D2O pool measurements accurately predicted chemically determined components with residual coefficients of variation below 5% and R2 greater than or equal to .90. However, total body D2O space provided as accurate an estimate of empty body water as the early-pool technique and may be easier to use because catheterization of blood vessels is not required. The incorporation of live weight and sex in multiple regression equations did not improve the accuracy of empty body water prediction over that obtained from D2O measurements alone. A method to estimate total body composition (water, protein, fat, ash) from the total body D2O space measurements is presented.