Insectivorous bats alter relative use of metabolic substrates to match requirements of their activities, including energetically expensive flight. The “fasting while foraging” hypothesis states that the metabolic demands of flight often exceed energy intake while foraging, hence bats may metabolize fat stores (especially early in the night) to power flight with ketones, a byproduct of the normal oxidation of fatty acids. Previous studies in bats have found increases in the plasma ketone ß-hydroxybutyrate following food consumption paired with or without flight. However, no study has explored whether increases in plasma ß-hydroxybutyrate occur following flight without food consumption. We used metabolite analysis to examine changes in plasma ß-hydroxybutyrate as a function of flight duration in 2 groups (fall and spring) of captive big brown bats (Eptesicus fuscus). We fasted bats for 12 hours prior to flight (exercise treatment) or rest (control), and then collected interfemoral vein blood. Exercise activity was quantified as flight time. For the Fall group, we collected three rest samples and one flight sample. Results for the Fall group were variable; interpretation of data patterns for this group may be complicated by changes in metabolism that occur in the fall when bats physiologically prepare for hibernation. To control for seasonal effects, we tested a second group of bats in the spring, collecting two rest and three flight samples. We found a positive correlation between flight duration and levels of plasma ß-hydroxybutyrate in the Spring group, which supports the fasting while foraging hypothesis. / Thesis / Master of Science (MSc) / The “fasting while foraging” hypothesis states that the metabolic demands of flight can exceed energy intake from recently consumed prey items, so insectivorous bats may metabolize fat stores (especially early in the night) to power flight with ketones, a byproduct of the normal oxidation of fatty acids. Previous studies in bats have found increases in the plasma ketone ß-hydroxybutyrate following food consumption, but no study has explored whether increases in plasma ß-hydroxybutyrate occur following flight without food consumption. We collected and analyzed blood to examine changes in plasma ß-hydroxybutyrate following different flight durations in big brown bats. We explored both seasonal and captivity effects. To explore seasonal effects, we sampled blood from bats in the fall and the spring, times that are biologically significant to big brown bats. The spring is when bats move out of torpor, a form of hibernation, into an active state and the fall is when bats are preparing for entering into torpor. To explore captivity effects, we sampled blood from bats recently introduced to or established to captivity. Bats were fasted for 12 hours prior to flight (exercise treatment) or rest (control), and then blood was collected. We characterized exercise using flight time. We found that plasma ß-hydroxybutyrate increased after longer flight durations, which supports the fasting while foraging hypothesis.
| Identifer | oai:union.ndltd.org:mcmaster.ca/oai:macsphere.mcmaster.ca:11375/25394 |
| Date | 11 June 2020 |
| Creators | Byron, Taylor |
| Contributors | Faure, Paul, Gillespie, Deda, Psychology |
| Source Sets | McMaster University |
| Language | English |
| Detected Language | English |
| Type | Thesis |
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