ROLE OF DIETARY FATTY-ACIDS ON ENERGETICS AND TORPOR IN THE CHILEAN MOUSE-OPOSSUM THYLAMYS ELEGANS

We hypothetized that the Chilean mouse-opossum Thylamys elegans needs micronutrients that are in fruits and seeds, and the unsaturated fatty acids are such micronutrients that may allow individuals of this spec ies to experience longer torpor bouts, lower body temperatures during torpor and higher energy savings during wintertime. To test this hypot hesis, we studied: 1) wintertime preferences by artificial diets rich in saturated fatty acids, unsaturated fatty acids and control diets, a nd 2) the effect of acclimation to dietary fatty acids on the energeti cs and torpor patterns in this species. When individuals where allowed to choose between the experimental diets they always selected the uns aturated fatty acid diet. After 4 weeks of dietary acclimation, the av erage daily metabolic rate was not significantly different among treat ments, neither was minimum metabolic rate during torpor significantly different, in spite of a tendency to lower values that was detected un der unsaturated fatty acid treatment. A similar pattern was observed w hen body temperature during torpor was compared among treatments. Two explanations are proposed: 1) Acclimation time was not sufficient to o btain statistical significance, but physiological differences and 2) m etabolic rate during torpor are not affected by dietary lipids in this species. Copyright (C) 1996 Elsevier Science Inc.