Abstract
Urinary urea nitrogen to creatinine ratios, urinary Nt-methylhistidine to creatinine ratios, serum urea nitrogen concentrations (SUN mg/dl), and serum Nt-methylhistidine concentrations were compared with physical measures of body composition in adult female barren-ground caribou (Rangifer tarandus groenlandicus) from the Bathurst and Southampton Island herds during late winter. Body weight and UUC were used to estimate urinary urea nitrogen (urea-N) excretion in free ranging caribou. Only mean UUC reflected differences in fat reserves between populations. None of the biochemical indicators were directly related to body composition. However, elevated UUC were only observed in caribou with depleted fat reserves as demonstrated by low kidney fat index (KFK40) and/or reduced femur marrow fat (FMF<80). UUC greater than 0.25 were indicative of undernourished animals with depleted fat reserves. SUN and UN -MHC showed no clear relationship with fat reserves. The mean estimated daily urea-N excretion for adult female caribou in late winter was extremely low (0.11+0.01SE g urea-N/day, n=76, range=0.011-0.510). The results of my study suggest that UUC can be used to detect nutritionally stressed caribou with depleted fat reserves on lichen winter ranges.
Highlights
Physical condition and nutritional status are impor tant parameters i n assessing the demography of carib o u (Rangifer tarandus) populations (Messier et al, 1988; Couturier et al, 1990)
39% (34 o f 87) o f the Bathurst caribou harvested had a K F I less than 30 and 6% (4 o f 70) had a F M F less than 50%. These differences i n fat reserves are reflected i n the significant (P
T h e results o f my study suggests that U U C can be used to monitor the nutritional status o f free ranging caribou o n lichen winter ranges and that analysis o f urine i n snow can be used to conduct physiological assessments caribou, as has been demonstrated i n deer (DelGiudice et al, 1989) and wapiti (DelGiudice et al, 1991c)
Summary
Physical condition and nutritional status are impor tant parameters i n assessing the demography of carib o u (Rangifer tarandus) populations (Messier et al, 1988; Couturier et al, 1990). B o d y measurements, tissue weights, and standard fat measurements were identified as useful indicators o f physical condition (Adamczewski et al, 1987a; H u o t , 1988; Allaye - C h a n , 1991). Allof these measurements required either killing or at least handling the animals. T h e nutritional status o f animals has often been inferred from condition analyses given that undernutrition will result i n depletion o f body reserves. Condition indicies provide little information about current nutritional status
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