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| 2. |
- Jenni-Eiermann, Susanne, et al.
(författare)
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Fuel use and metabolic response to endurance exercise: a wind tunnel study of a long-distance migrant shorebird
- 2002
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Ingår i: Journal of Experimental Biology. - 1477-9145. ; 205:16, s. 2453-2460
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Tidskriftsartikel (refereegranskat)abstract
- This study examines fuel use and metabolism in a group of long-distance migrating birds, red knots Calidris canutus (Scolopacidae), flying under controlled conditions in a wind tunnel for up to 10 h. Data are compared with values for resting birds fasting for the same time. Plasma levels of free fatty acids, glycerol and uric acid were elevated during flight, irrespective of flight duration (1-10h). Triglyceride levels, the estimated concentration of very-low-density lipoproteins (VLDLs) and beta-hydroxybutyrate levels were lower during flight, while glucose levels did not change. In flying birds, plasma levels of uric acid and lipid catabolites were positively correlated with the residual variation in body mass loss, and lipid catabolites with energy expenditure (as measured using the doubly labelled water method), after removing the effect of initial body mass. The plasma metabolite levels indicate: (i) that the rates of catabolism of lipids from adipose tissue and of protein are higher during flight; (H) that low ketone body concentrations probably facilitate fatty acid release from adipose tissue; (iii) that low triglyceride and VLDL levels do not indicate the use of an additional pathway of fatty acid delivery, as found in small birds; and (iv) that the relationships between energy expenditure, body mass loss and metabolic pattern suggest that a higher individual energy expenditure entails a higher rate of catabolism of both lipids and protein and not a shift in fuel substrate.
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| 3. |
- Klaassen, M, et al.
(författare)
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Flight costs and fuel composition of a bird migrating in a wind tunnel
- 2000
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Ingår i: The Condor: ornithological applications. - 0010-5422. ; 102:2, s. 444-451
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Tidskriftsartikel (refereegranskat)abstract
- We studied the energy and protein balance of a Thrush Nightingale Luscinia luscinia, a small long-distance migrant, during repeated 12-hr long Eights in a wind tunnel and during subsequent two-day fueling periods. From the energy budgets we estimated the power requirements for migratory flight in this 26 g bird at 1.91 Watts. This is low compared to flight cost estimates in birds of similar mass and with similar wing shape. This suggests that power requirements for migratory flight are lower than the power requirements for nonmigratory Eight. From excreta production during Right, and nitrogen and energy balance during subsequent fueling, the dry protein proportion of stores was estimated to be around 10%. A net catabolism of protein during migratory flight along with that of fat may reflect a physiologically inevitable process, a means of providing extra water to counteract dehydration, a production of uric acid for anti-oxidative purposes, and adaptive changes in the size of Eight muscles and digestive organs in the exercising animal.
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| 4. |
- Kvist, Anders, et al.
(författare)
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Basal metabolic rate in migratory waders: intra-individual, intraspecific, interspecific and seasonal variation
- 2001
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Ingår i: Functional Ecology. - : Wiley. - 1365-2435 .- 0269-8463. ; 15:4, s. 465-473
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Tidskriftsartikel (refereegranskat)abstract
- 1. Basal metabolic rates (BMR) were measured in 36 adult and 119 juvenile waders of 19 species on autumn migration in southern Sweden. 2. Ina comparison with literature data, it was found that juvenile BMR was generally lower than at the onset of migration in the Arctic and slightly higher than on African wintering grounds. 3. The seasonal differences may reflect local physiological adaptations or possibly a gradual decline from high premigratory levels due to growth. Our data contradict the idea that BMR is high during migration as an adaptation to generally high levels of energy expenditure. 4. The allometric exponent, scaling BMR to body mass, was significantly higher within individuals (1.19) and within species (1.82) than among species (0.62). 5. The high intra-individual exponent indicates that non-fat tissues, with a high metabolic activity, are involved in the mass changes during migratory stopover. 6. The high intraspecific exponent indicates that tissues with a high metabolic activity contributed disproportionately to variation in body mass among individuals or that larger individuals had elevated mass specific metabolic rates of some tissues.
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| 5. |
- Kvist, Anders, et al.
(författare)
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Carrying large fuel loads during sustained bird flight is cheaper than expected
- 2001
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Ingår i: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 413:6857, s. 730-732
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Tidskriftsartikel (refereegranskat)abstract
- Birds on migration alternate between consuming fuel stores during flights and accumulating fuel stores during stopovers. The optimal timing and length of flights and stopovers for successful migration depend heavily on the extra metabolic power input (fuel use) required to carry the fuel stores during flight(1,2). The effect of large fuel loads on metabolic power input has never been empirically determined. We measured the total metabolic power input of a long-distance migrant, the red knot (Calidris canutus), flying for 6 to 10 h in a wind tunnel, using the doubly labelled water technique(3). Here we show that total metabolic power input increased with fuel load, but proportionally less than the predicted mechanical power output from the flight muscles. The most likely explanation is that the efficiency with which metabolic power input is converted into mechanical output by the flight muscles increases with fuel load. This will influence current models of bird flight and bird migration. It may also help to explain why some shorebirds, despite the high metabolic power input required to fly, routinely make nonstop flights of 4,000 km longer(4).
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| 6. |
- Kvist, Anders
(författare)
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Fuel and fly: adaptations to endurance exercise in migrating birds
- 2001
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Birds on migration alternate between consuming fuel stores during flights and accumulating fuel stores during stopovers. This thesis highlights some of the ways in which migrating birds have adapted to the different demands of fuelling and flight. Most of the time on migration is spent at stopover sites accumulating fuel stores. To minimise the total time spent on migration, birds should fuel up as fast as possible. I show that migrating birds have an exceptional energy assimilation capacity, enabling rapid accumulation of fuel stores. Migrating birds can increase their daily energy assimilation, and fuel accumulation rates, by utilizing a larger part of the day for foraging. There is also evidence for an adaptive flexibility in this digestive capacity and that digestive capacity can be built up rapidly following depletion of fuel stores due to flight. Fuel economy is crucial during long distance migratory flights. I present the first estimates of metabolic power, or rate of fuel consumption, for migratory birds performing sustained flight in a windtunnel. The way metabolic power increases with body mass in the red knot (Calidris canutus) indicate that the flight muscles are adapted for fuel efficiency in long flights with heavy fuel loads. Metabolic power curves and minimum power speeds for a thrush nightingale (Luscinia luscinia) and a teal (Anas crecca), estimated from mass loss rate, indicate that the drag of the birds bodies in flight is lower than previously thought. Fat is the main fuel for long migratory flights. I show that protein makes a significant contribution to the energy metabolism during sustained flights in the thrush nightingale. Net protein catabolism may reflect physiologically inevitable processes, may provide extra water to counteract dehydration during flight, or may reflect adaptive changes in the size of organs. Intraindividual variation in BMR, protein catabolism during flight and protein deposition during fuelling all indicate that migrants flexibly adapt their morphology and physiology to the different demands of fuelling and flight. Changes in pectoral muscle size of red knots may be an adaptation to maintain optimal flight performance when body mass varies. Maintaining heat balance in flying birds, especially at high ambient temperatures, can create problems with water balance. Red knots flying at lower ambient temperatures regulated dry heat loss and maintained water loss at a constant low level. At higher temperatures evaporative heat loss increased sharply, resulting in a net water loss. Maximum flight range in migrating birds imposed by energy and water budgets are predicted using an updated physiological computer model. Comparing the outcome of this model with experimental data indicate that the model predictions appear to be realistic but are associated with considerable uncertainties.
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| 7. |
- Kvist, Anders, et al.
(författare)
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Gluttony in migratory waders - unprecedented energy assimilation rates in vertebrates
- 2003
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Ingår i: Oikos. - : Wiley. - 1600-0706 .- 0030-1299. ; 103:2, s. 397-402
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Tidskriftsartikel (refereegranskat)abstract
- Maximum energy assimilation rate has been implicated as a constraint on maximal sustained energy expenditure, on biomass production, and in various behavioural and life history models. Data on the upper limit to energy assimilation rate are scarce, and the factors that set the limit remain poorly known. We studied migratory waders in captivity, given unlimited food supply around the clock. Many of these waders assimilated energy at rates of seven to ten times basal metabolism, exceeding maximum rates reported for vertebrates during periods of high energy demand, for example during reproduction and in extreme cold. One factor allowing the high energy assimilation rates may be that much of the assimilated energy is stored and not concomitantly expended by muscles or other organs. The remarkable digestive capacity in waders is probably an adaptation to long and rapid migrations, putting a premium on high energy deposition rates. The upper limit to daily energy assimilation in vertebrates is clearly higher than hitherto believed, and food availability, total daily feeding time and, possibly, the fate of assimilated energy may be important factors to take into account when estimating limits to energy budgets in animals.
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| 8. |
- Kvist, Anders, et al.
(författare)
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Maximum daily energy intake: It takes time to lift the metabolic ceiling
- 2000
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Ingår i: Physiological and Biochemical Zoology. - 1522-2152. ; 73:1, s. 30-36
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Tidskriftsartikel (refereegranskat)abstract
- Conventionally, maximum capacities for energy assimilation are presented as daily averages. However, maximum daily energy intake is determined by the maximum metabolizable energy intake rate and the time available for assimilation of food energy Thrush nightingales (Luscinia luscinia) in migratory disposition were given limited food rations for 3 d to reduce their energy stores. Subsequently, groups of birds were fed ad lib. during fixed time periods varying between 7 and 23 h per day. Metabolizable energy intake rate, averaged over the available feeding time, was 1.9 W and showed no difference between groups on the first day of refueling. Total daily metabolizable energy intake increased linearly with available feeding time, and for the 23-h group, it was well above suggested maximum levels for animals. We conclude that both intake rate and available feeding time must be taken into account when interpreting potential constraints acting on animals' energy budgets. In the 7-h group, energy intake rates increased from 1.9 W on the first day to 3.1 W on the seventh day. This supports the idea that small birds can adaptively increase their energy intake rates on a short timescale.
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| 9. |
- Kvist, Thomas, 1959, et al.
(författare)
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Microbiological evaluation of one- and two-visit endodontic treatment of teeth with apical periodontitis: a randomized, clinical trial.
- 2004
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Ingår i: Journal of endodontics. - 0099-2399. ; 30:8, s. 572-6
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Tidskriftsartikel (refereegranskat)abstract
- The antimicrobial efficacy of endodontic procedures performed in one-visit (including a 10-min intraappointment dressing with 5% iodine-potassium-iodide) was compared with a two-visit procedure (including an interappointment dressing with calcium-hydroxide paste). Teeth with apical periodontitis (n = 96) were randomly assigned to either group. Root canal sampling and culturing were performed before and immediately after instrumentation, and after medication. Initial sampling demonstrated the presence of microorganisms in 98% of the teeth. Postinstrumentation sampling showed reduction of cultivable microbiota. Antibacterial dressing further reduced the number of teeth with surviving microbes. In the postmedication samples, residual microorganisms were recovered in 29% of the one-visit teeth and in 36% of the two-visit treated teeth. No statistically significant differences between the groups were discerned. It was concluded that from a microbiological point of view, treatment of teeth with apical periodontitis performed in two appointments was not more effective than the investigated one-visit procedure.
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| 10. |
- Lindström, Åke, et al.
(författare)
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Avian pectoral muscle size rapidly tracks body mass changes during flight, fasting and fuelling
- 2000
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Ingår i: Journal of Experimental Biology. - 1477-9145. ; 203:5, s. 913-919
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Tidskriftsartikel (refereegranskat)abstract
- We used ultrasonic imaging to monitor short-term changes in the pectoral muscle size of captive red knots Calidris canutus. Pectoral muscle thickness changed rapidly and consistently in parallel with body mass changes caused by flight, fasting and fuelling. Four knots flew repeatedly for 10 h periods in a wind tunnel. Over this period, pectoral muscle thickness decreased in parallel with the decrease in body mass. The change in pectoral muscle thickness during flight was indistinguishable from that during periods of natural and experimental fasting and fuelling. The body-mass-related variation in pectoral muscle thickness between and within individuals was not related to the amount of flight, indicating that changes in avian muscle do not require power-training as in mammals. Our study suggests that it is possible for birds to consume and replace their flight muscles on a time scale short enough to allow these muscles to be used as part of the energy supply for migratory flight. The adaptive significance of the changes in pectoral muscle mass cannot be explained by reproductive needs since our knots were in the early winter phase of their annual cycle. Instead, pectoral muscle mass changes may reflect (i) the breakdown of protein during heavy exercise and its subsequent restoration, (ii) the regulation of flight capacity to maintain optimal flight performance when body mass varies, or (iii) the need for a particular protein:fat ratio in winter survival stores.
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