Deuterium oxide dilution kinetics to predict body composition in dairy goats

Body composition and D2O dilution kinetics were studied in 15 female goats ranging from 38.0 to 70.1 kg live weight. Infrared spectrophotometric analyses of blood samples drawn during the 4 d following D2O injections were used to estimate D2O space. All does were slaughtered without shrinking and analyzed for dry matter, fat, nitrogen, and ash content. Estimates of D2O space from the late slope of the dilution curve, together with live weight, were used to predict body composition. Conclusions were 1) deuterium oxide space with live body weight accounts for about 90% of the variation in dairy goat empty body fat, empty body nitrogen, and empty body dry matter; 2) less than half the variation in empty body ash is related to live weight and D2O space; and 3) D2O space estimates would be biased by accelerations in water turnover.