Tritiated water for estimating total body water and water turnover rate in birds

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Abstract
The use of tritiated water (TOH) to estimate total body water (TBW) and total water turnover rate was validated in chukar partridges (Alectoris chukar) and sand patridges (Ammoperdix heyi). For 6 chikar partridges weighing between 315-475 g, TOH equilibration with body fluids was < 45 min after i.m. or i.v. injections. Mean TOH space in 8 chukar partridges was 99.8% of the mean TBW measured by desiccation with individuals ranging between 97.9-103.2%. TOH space best approximated TBW when TBW was calculated by using the mean body mass for a bird weighed at TOH injection and at TOH equilibration. Total water intake as estimated by TOH ranged between 90.7-113.3% of measured water intake in 3 sand and 3 chukar partridges, birds ranging in mass from 145-446 g. The TOH method provides accurate estimations of TBW and water turnover rates in birds. For birds of up to 500-g body mass, 45 min for TOH equilibration with body fluids, and i.m. injections of 0.05 .mu.Ci TOH/g body mass for TBW estimations and 0.1 .mu.Ci TOH/g body mass for water turnover estimations are recommended.