Measurement of Water Kinetics with Deuterium Oxide in Lactating Dairy Cows

Abstract

Following intravenous infusion with approximately 300 mg deuterium oxide per kg body weight, blood was drawn from lactating Holsteins (Trial 1, n = 4, and Trial 2, n = 5) at suitable intervals for up to 12 days while the cows were maintained on dietary regimens to which they were well adapted. Time results for deuterium oxide concentration in blood were described best by the three-compartment open model system, which showed that the central, shallow peripheral, and deep peripheral body water compartments contained 27.1, 25.0, and 23.2% body weight in trial 1 and 33.7, 27.1, and 19.9% body weight in trial 2. Total body water estimates averaged 75.3 and 80.7% body weight during trials 1 and 2. Estimates for biological half-life of water were 4.6 and 3.2 days and those for water turnover were 68.9 and 109.7 liters/day, respectively. The data fitted the two-compartment open model system when observations made prior to 25 min post-administration were excluded from the analyses, because the central and shallow peripheral compartments were apparently lumped into one. Blood sampling at 0.5, 1, and 1.5 days following infusion and thereafter at 1-day intervals was adequate for the estimates of the one compartment open model system. Estimates of total body water, water biological half-life, and water turnover were similar for the different models. It is concluded that the three-compartment open model provides greater detail and insight into the water dynamics of lactating dairy cows having regular access to food and water, whereas the two- and one-compartment open model systems provide good approximations only.

A two-pool model of tritiated water kinetics to predict body composition in unfasted lactating goats

“…Byers (1979) proposed that the two water pools generated from such a model approximated EBW and GW in cattle. Generally, if blood sampling did not commence until 15 min or longer after administration of the tracer, a second-order exponential model provided the best fit to the data (Byers, 1979;Ferrell and Jenkins, 1984;Odwongo et al, 1985;Martin and Ehle, 1986). Generally, if blood sampling did not commence until 15 min or longer after administration of the tracer, a second-order exponential model provided the best fit to the data (Byers, 1979;Ferrell and Jenkins, 1984;Odwongo et al, 1985;Martin and Ehle, 1986).…”

“…More recently, attention has been directed to using models of water kinetics which include two or more water pools in efforts to separate GIT water from empty body water (EBW) in ruminants (Byers, 1979;Ferrell and Jenkins, 1984;Odwongo, Conrad and Staubus, 1984;Arnold, Hentges and Trenkle, 1985;Faichney and Boston, 1985;Odwongo, Conrad, Staubus and Harrison, 1985). The work reported in this paper is part of a series of experiments investigating the amount of fat mobilized by' dairy goats during early lactation.…”

Evaluation of the Difference in Body Composition of Thai Native Cattle and Swamp Buffaloes from that of Holstein Cattle in Northeast Thailand Using Urea Space

“…Measurement of tritium and deuterium is another method for determining body composition. Tritium or deuterium spread evenly and rapidly and are not toxic; they result in no deleterious physiologic effect and are not selectively stored 1,10 . Measurements of body water or of tritium and deuterium are unsuitable for field experiments, because they require several days to determine body water turnover rate, and persons using the techniques need special equipment to analyze the tritium and deuterium 2 .…”

Modeling the movement and equilibration of water in the body of ruminants in relation to estimating body composition by deuterium oxide dilution

“…Thus, while isotope dilution methods have been developed using two-compartment kinetic models, the usefulness of this approach has not been evaluated by comparisons with directly measured body composition. A two-compartment kinetic model, without adjusting compartment volumes by regression equations, have been used (Woodford et al, 1984;Odwongo et al, 1985) to describe the water dynamics of dairy cows, but the relevancy of predicted compartment volumes to actual anatomical compartments are not known.…”

“…Thus, attempts have been made to increase the number of compartments in order to account for the total isotope disappearance curve for blood instead of truncating the curve. When the earliest sampling times for blood were every 5 min during the first 70 min after the isotope was dosed, three exponential components were fitted to the disappearance curve Odwongo et al, 1985), however, when blood was sampled every 10 min for the first hour after dosing the isotope, only two exponential components were fitted to the disappearance curve (Woodford et al, 1984). developed regression equations for predicting body composition from calculated water volumes of the three compartments.…”