Meeting Abstract
Thermoregulation accounts for a substantial part of an endothermic animal’s energy budget. Higher metabolic requirements due to thermoregulation are typically met by aerobic metabolism, thus temperature acclimation may also affect oxygen supply via the blood. We investigated the relationship between metabolic rates (MRs) and hematological variables (HVs), specifically hemoglobin concentration (Hb); hematocrit (Hct); red blood cell count (RBCc) and red blood cell area (RBCarea) in birds acclimated to different temperatures. Female zebra finches (Taeniopygia guttata) were maintained for seven weeks either in cold Ta = 12 °C (N = 39) or thermo-neutral Ta = 32 °C conditions (N = 40). Following acclimation, we also determined mass specific food intake, basal metabolic rate during rho phase (BMRρ) and maximum metabolic rate (MMR); we drew blood samples to measure HVs. Principal component analysis (PCA) was used to reduce the number of variables and its components were used to analyze the relationship between HVs and MRs. Body mass and food intake were higher in cold- than in warm-acclimated birds, while BMRρ and MMR were not different between the temperatures. Principal component analysis revealed that PC1 explains 63% and PC2 25% of the variations, with Hb, Hct, and RBCc grouping in PC1 with equally high, positively related Eigenvalues. Erythrocyte area (RBCarea) largely accounted for PC2. Both PC1 and PC2 were negatively related to food intake, but not significantly related to BMRρ and MMR. Lower values for Hb, Hct and RBCc in concert (PC1) and smaller red blood cells (PC2) relate to higher food intake. The HVs appear to be negatively related to daily energy use, but not related to energy costs of self-maintenance.
