Energy values of body in small mammals

Abstract

[With 3 Tables and 5 Figs.l Energy values cf the body were examined in 5 species of small mammals prevailing in the forest and field ecosystems: Sorex araneus L., Apodemus flavicollis (M e 1 c h.), Apodemus agrarius (Pal 1.), Clethrio-nomys glareolus (S c h r e b.), and Microtus arvalis (P a 11.). A total of 270 samples derived from 220 animals caught in 3 seasons (late winter and prevernal season, summer, and autumn) were burned in the bomb calorimeter. The caloric value per gram dry weight and the per cent water and ash were determined and the cal/g ash-free values and the values of biomass were calculated. In the examined rodents the cai/g dry weight value is the lowest at the end of winter (4508.44 cal/g). In the summer it goes up rapidly to reach 5261.05 cal/g and a similar value is maintained in the autumn (5204.08 cal/g). The caloric value of body for shrews does not show any seasonal changes, being low all the year round (4554.96 cal/g). The caloric value per gram ash-free weight exceeds by 10.2-13.7% the cal/g dry weight value, showing very similar specific and seasonal variations. The seasonal fluctuations and specific differences in these values depend mainly on the fatness and only slightly on the ash content. The energy value of biomass for all the species and seasons falls within a narrow range of 1301-1693 cal/g, with an average of 1501' cal/g. Consequently, either this mean value, 1.5 Kcal/g, will be used to calculate the productivity of populations of small mammals or the coefficient may be differentiated for seasons and species.