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Using breath δ13C analysis to determine the effects of dietary carbohydrate and protein on glucose and leucine oxidation at rest in the yellow-rumped warbler (Setophaga coronata)
Fat is the major fuel for migratory flight of birds, but protein is also catabolized. Flight range could be reduced if protein is used too quickly from muscles and organs, and it is important to understand factors that influence protein catabolism. Previous correlative studies suggested high protein...
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| Published in: | Comparative biochemistry and physiology. Part A, Molecular & integrative physiology Molecular & integrative physiology, 2021-06, Vol.256, p.110936-110936, Article 110936 |
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| Main Authors: | , , , |
| Format: | Article |
| Language: | English |
| Subjects: | |
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| Online Access: | Get full text |
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| Summary: | Fat is the major fuel for migratory flight of birds, but protein is also catabolized. Flight range could be reduced if protein is used too quickly from muscles and organs, and it is important to understand factors that influence protein catabolism. Previous correlative studies suggested high protein diets may increase protein use in flight, although a wind tunnel study with yellow-rumped warblers (Setophaga coronata) did not support this relationship. We tested the hypothesis that diet composition affects nutrient oxidation in resting, fasted yellow-rumped warblers. For method development, we gavaged or subcutaneously injected warblers with 13C labelled glucose or leucine, and measured δ13C of breath CO2 in real time using infrared laser spectrometry. Regardless of route of administration, leucine had greater instantaneous and cumulative oxidation than glucose. Compared to subcutaneous injection, gavaged birds reached maximum oxidation rate faster for leucine and glucose, respectively, had a higher maximum oxidation rate, and reached final cumulative oxidation approximately faster for leucine or glucose, respectively, indicating immediate oxidation of the substrates by the digestive system. Warblers (N = 10 each) were fed isocaloric 60% carbohydrate or 60% protein diets for minimum 2 weeks, and subcutaneously injected with 13C labelled glucose or leucine. Diet composition had little effect on oxidation kinetics except that warblers fed high-carbohydrate reached final cumulative oxidation of leucine more quickly than those fed high-protein. The findings do not support the hypothesis that high protein diets increase the oxidation of protein during negative energy states in migratory birds, and provide methodology that could be applied to test it in flight.
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•Infrared laser spectrometry captures macronutrient oxidation at 1 s intervals•Substrates are oxidized faster when gavaged than when injected•Leucine is oxidized faster than glucose•Diet carbohydrate and protein proportion did not affect substrate oxidation |
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| ISSN: | 1095-6433 1531-4332 |
| DOI: | 10.1016/j.cbpa.2021.110936 |