Meeting Abstract

P1.110  Sunday, Jan. 4  The effects of dietary (n-3) and (n-6) oils on basal metabolic rate in zebra finches. AMITAI, Oren*; BAUCHINGER, Ulf; MCCUE, Marshall D; PINSHOW, Berry; Ben-Gurion University of the Negev; Ben-Gurion University of the Negev; Ben-Gurion University of the Negev; Ben-Gurion University of the Negev orenamit@bgu.ac.il

Dietary fatty acid (FA) profiles play an important role in the composition of cell membranes. The unsaturation level of cell membranes of birds and mammals have been shown to be positively correlated with basal metabolic rate (BMR), but it is unclear whether the unsaturation levels of dietary FAs are the underlying cause of alterations in metabolic rate. Docosahexaenoic acid (DHA; 22:5 n-3), produced from dietary linolenic acid (18:3 n-3), is a highly unsaturated FA found in cell membranes of all vertebrates and is central to the Hulbert and Else membrane “pacemaker” theory. We therefore tested the prediction that birds fed a diet enriched with (n-3) FAs have higher BMR than birds fed a diet enriched with (n-6) FAs. We used 18 Zebra finches (Taeniopygia guttata, 9 males and 9 females) that were separated by sex and divided into three groups and fed millet diets supplemented with 8% safflower (n-6), 8% flaxseed oil (n-3), or no oil for 7-12 days. BMR was measured by indirect calorimetry on 6 birds at a time (2 from each group) on days 7, 9 and 12. Mean BMR’s for control, (n-3) and (n-6) were 0.29±0.02, 0.26±0.05 and 0.32±0.06 W, respectively, and were not significantly different (ANOVA, F_(2,14)=2.79, P = 0.095). The data in hand do not support the prediction; in fact they indicate that BMR is lower in (n-3) fed birds. We conclude that, as has been suggested (D.J. McKenzie, 2000) for sturgeon and other fish, the BMR response to dietary fat may not be confined to the cell membrane, but may operate at the whole cell, or organ level as well.