Meeting Abstract
Saturation level of fatty acids (FA) in birds’ tissues is known to affect the energetic costs of short and long-term flights: polyunsaturated fatty acid (PUFA) fed birds fly about 10% cheaper compared to monounsaturated fatty acid (MUFA) fed birds, but the underlying mechanism remains unknown. Membrane hypothesis, proposes that the saturation level of FA affects the fluidity of cell membranes and thus their functions across membrane processes. Specifically, FA composition of red blood cells (RBC) membranes can affect their deformability and thus cost of transport of blood. We fed 37 European Starlings with either a diet rich in PUFA or MUFA and split each diet group into flying birds (about 900 km in a wind-tunnel) and non-flying birds. For all birds, we measured basal metabolic rate (BMR) and haematological variables (HVs) (haematocrit, haemoglobin content, number and size of RBC). Neither BMR, nor any HVs were different between diet and training groups. The relationships between BMR and both, haemoglobin and haematocrit were significantly affected by diet, not training (individual correlations BMR-haemoglobin and BMR-haematocrit for each diet did not differ from 0). Significant interactions suggest different diet effect on HVs. Significant contribution of HVs, here haemoglobin content and haematocrit, to whole animal energy expenditure might be even more pronounced when considering flight costs instead of BMR. Lower heart-specific energy use for circulation of blood caused by lower blood viscosity due to more deformable cells for PUFA-fed birds may contribute to differences in flight costs.
