Meeting Abstract

18.3  Tuesday, Jan. 4  The early developmental environment affects the energetic cost of homeothermy in ducklings. DURANT, S.E.*; HOPKINS, W.A.; AMANDA, A.F; HEPP, G.R.; Virginia Tech; Virginia Tech; Virginia Tech; Auburn University sdurant@vt.edu

Development of homeothermy requires maturation of integument and skeletal muscle tissues, with protein content of the latter being especially important for thermogenesis. A previous study in wood ducks (Aix sponsa) revealed that ducklings that hatched from eggs incubated at lower temperatures had lower protein content than ducklings incubated at higher temperatures. Therefore, we predicted that ducklings incubated at lower temperatures would be less effective and efficient at maintaining their body temperature during a thermal challenge. To test our hypothesis we incubated wood duck eggs at three temperatures (35.0, 35.9, and 37.0°C), that fall within the range of temperatures of naturally-incubated wood duck nests. Twenty-four hrs after hatching we used ducklings in one of two thermal challenge experiments. In the first experiment we measured the change in a ducklings’ body temperature after being held at thermoneutrality (36°C) for 1 hr and then exposed to either 5, 10, 15, 20°C, or 36°C (control) for an additional hr. In the second experiment we measured energy expenditure of ducklings for 1hr at 36°C then for 1hr at 15°C. We found that all ducklings were less effective at maintaining their body temperature at the lower thermal challenge temperatures, but incubation temperature did not influence the change in duckling body temperature. However, ducklings from the lowest incubation temperature exhibited a greater increase in respiration during the thermal challenge than ducklings incubated at the higher temperatures. These results suggest that ducklings incubated at the lowest temperature expend more energy to maintain their body temperature than ducklings incubated at the higher temperatures.