Laurel S. Duquette Ulysses S. Seal L. David Mech Glenn D. DelGiudice 1991 <p>We studied ²²sodium (²²Na) turnover as a means of estimating food intake in 6 captive, adult gray wolves (<i>Canis lupus</i>) (2 F, 4 M) over a 31-day feeding period. Wolves were fed white-tailed deer (<i>Odocoileus virginianus</i>) meat only. Mean mass-specific exchangeable Na pool was 44.8 <span>±</span>&nbsp;0.7 mEq/kg; there was no differeence between males and females. Total exchangeable Na was related (<i>r</i>² = 0.85, <i>P</i> &lt; 0.009) to body mass. Overall, ²²Na turnover overestimated Na intake by 9.8 <span>±</span>&nbsp;2.4% after 32 days. Actual Na intake was similar in males and females; however, Na turnover (<i>P</i> &lt; 0.05) and the discrepancy (<i>P</i> &lt; 0.01) between turnover and actual Na intake were greater in females than males. From Day 8 to the end of the study, the absolute difference (mEq) between Na intake and Na turnover remained stable. Sodium turnover (mEq/kg/day) was a reliable (<i>r</i>² = 0.91, <i>P</i> &lt; 0.001) estimator of food consumption (g/kg/day) in wolves over a 32-day period. Sampling blood and weighing wolves every 1-4 days permitted identification of several potential sources of error, including changes in size of exchangeable Na pools, exchange of ²²Na with gastrointestinal and bone Na, and rapid loss of the isotope by urinary excretion.</p> application/pdf 10.2307/3809241 en Wiley Validation of estimating food intake in gray wolves by 22Na turnover article