Energetic costs of digestion in Australian crocodiles

We measured standard metabolic rate (SMR) and the metabolic response to feeding in the Australian crocodiles, Crocodylus porosus and C. johnsoni. Both species exhibit a response that is characterised by rapidly increasing metabolism that peaks within 24 h of feeding, a postfeeding metabolic peak (peak O2) of 1.4–2.0 times SMR, and a return to baseline metabolism within 3–4 days after feeding. Postfeeding metabolism does not significantly differ between species, and crocodiles fed intact meals have higher total digestive costs (specific dynamic action; SDA) than those fed homogenised meals. Across a more than 100-fold range of body size (0.190 to 25.96 kg body mass), SMR, peak O2, and SDA all scale with body mass to an exponent of 0.85. Hatchling (≤1 year old) C. porosus have unexpectedly high rates of resting metabolism, and this likely reflects the substantial energetic demands that accompany the rapid growth of young crocodilians.

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The scaling and temperature dependence of vertebrate metabolism

Biology Letters ◽

10.1098/rsbl.2005.0378 ◽

2005 ◽

Vol 2 (1) ◽

pp. 125-127 ◽

Cited By ~ 226

Author(s):

Craig R White ◽

Nicole F Phillips ◽

Roger S Seymour

Keyword(s):

Body Size ◽

Metabolic Rate ◽

Temperature Dependence ◽

Body Mass ◽

Standard Metabolic Rate ◽

Power Scaling ◽

Scaling Exponents ◽

Magnitude Variation ◽

Over 40 Years

Body size and temperature are primary determinants of metabolic rate, and the standard metabolic rate (SMR) of animals ranging in size from unicells to mammals has been thought to be proportional to body mass ( M ) raised to the power of three-quarters for over 40 years. However, recent evidence from rigorously selected datasets suggests that this is not the case for birds and mammals. To determine whether the influence of body mass on the metabolic rate of vertebrates is indeed universal, we compiled SMR measurements for 938 species spanning six orders of magnitude variation in mass. When normalized to a common temperature of 38 °C, the SMR scaling exponents of fish, amphibians, reptiles, birds and mammals are significantly heterogeneous. This suggests both that there is no universal metabolic allometry and that models that attempt to explain only quarter-power scaling of metabolic rate are unlikely to succeed.

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Metabolic response to feeding and fasting in the water python (Liasis fuscus)

Australian Journal of Zoology ◽

10.1071/zo01017 ◽

2001 ◽

Vol 49 (4) ◽

pp. 379 ◽

Cited By ~ 18

Author(s):

Gavin S. Bedford ◽

Keith A. Christian

Keyword(s):

Metabolic Rate ◽

Body Mass ◽

Metabolic Response ◽

Standard Metabolic Rate ◽

Meal Size ◽

Digestive Physiology ◽

Small Prey ◽

Feeding And Fasting

Compared with other reptiles, pythons have a relatively low standard metabolic rate (SMR) when post-absorptive, but metabolism increases substantially after feeding. This study examined the effects of feeding and fasting on adult and hatchling water pythons (Liasis fuscus). We compared ratios of peak digestive metabolic rate (PDMR) after feeding with the metabolic rate of both post-absorptive (SMR) and fasted water pythons. If metabolic rate of a fasting snake is taken as ‘SMR’, then the ratio PDMR/SMR becomes increasingly exaggerated as fasting continues. After 56 days of fasting in adults, or after 45 days in hatchlings, the metabolic rate of water pythons was significantly lower than that of post-absorptive animals. Peak digestive metabolic rate of post-absorptive adult water pythons was only 6.3–12.0 times SMR, but the ratio was twice that if fasted (metabolically depressed) animals were used to determine the ‘SMR’ denominator. Thus, this ratio should be used with caution. Peak digestive metabolic rate after feeding increased with increasing meal size for meals less than 20% of body mass, but PDMR did not increase for meals between 20% and 39% of body mass for adult water pythons. Similarly, the PDMR did not increase signif icantly between 25% and 50% meal sizes for hatchlings. The digestive physiology of water pythons is apparently better suited to frequent meals of relatively small prey compared with the digestive physiology of some other pythons.

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Effects of body mass and temperature on standard metabolic rate of the herbivorous desert lizardUromastyx philbyi

Journal of Arid Environments ◽

10.1006/jare.1996.0081 ◽

1996 ◽

Vol 33 (4) ◽

pp. 457-461 ◽

Cited By ~ 7

Author(s):

Talal A. Zari

Keyword(s):

Metabolic Rate ◽

Body Mass ◽

Standard Metabolic Rate

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Body size and temperature effects on standard metabolic rate for determining metabolic scope for activity of the polychaete Hediste (Nereis) diversicolor

PeerJ ◽

10.7717/peerj.5675 ◽

2018 ◽

Vol 6 ◽

pp. e5675 ◽

Cited By ~ 3

Author(s):

Helena Lopes Galasso ◽

Marion Richard ◽

Sébastien Lefebvre ◽

Catherine Aliaume ◽

Myriam D. Callier

Keyword(s):

Oxygen Consumption ◽

Body Size ◽

Metabolic Rate ◽

Growth Rates ◽

Reaction Rate ◽

Specific Growth ◽

Standard Metabolic Rate ◽

Metabolic Scope ◽

Specific Growth Rates ◽

Arrhenius Temperature

Considering the ecological importance and potential value of Hediste diversicolor, a better understanding of its metabolic rate and potential growth rates is required. The aims of this study are: (i) to describe key biometric relationships; (ii) to test the effects of temperature and body size on standard metabolic rate (as measure by oxygen consumption) to determine critical parameters, namely Arrhenius temperature (TA), allometric coefficient (b) and reaction rate; and (iii) to determine the metabolic scope for activity (MSA) of H. diversicolor for further comparison with published specific growth rates. Individuals were collected in a Mediterranean lagoon (France). After 10 days of acclimatization, 7 days at a fixed temperature and 24 h of fasting, resting oxygen consumption rates (VO2) were individually measured in the dark at four different temperatures (11, 17, 22 and 27 °C) in worms weighing from 4 to 94 mgDW (n = 27 per temperature). Results showed that DW and L3 were the most accurate measurements of weight and length, respectively, among all the metrics tested. Conversion of WW (mg), DW (mg) and L3 (mm) were quantified with the following equations: DW = 0.15 × WW, L3 = 0.025 × TL(mm) + 1.44 and DW = 0.8 × L33.68. Using an equation based on temperature and allometric effects, the allometric coefficient (b) was estimated at 0.8 for DW and at 2.83 for L3. The reaction rate (VO2) equaled to 12.33 µmol gDW−1 h−1 and 0.05 µmol mm L3−1 h−1 at the reference temperature (20 °C, 293.15 K). Arrhenius temperature (TA) was 5,707 and 5,664 K (for DW and L3, respectively). Metabolic scope for activity ranged from 120.1 to 627.6 J gDW−1 d−1. Predicted maximum growth rate increased with temperature, with expected values of 7–10% in the range of 15–20 °C. MSA was then used to evaluate specific growth rates (SGR) in several experiments. This paper may be used as a reference and could have interesting applications in the fields of aquaculture, ecology and biogeochemical processes.

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Incubation temperature and physiological aging in the zebra finch

PLoS ONE ◽

10.1371/journal.pone.0260037 ◽

2021 ◽

Vol 16 (11) ◽

pp. e0260037

Author(s):

Henrik H. Berntsen ◽

Claus Bech

Keyword(s):

Body Size ◽

Oxidative Damage ◽

Metabolic Rate ◽

Body Mass ◽

Basal Metabolic Rate ◽

Incubation Temperature ◽

Phenotypic Variability ◽

Body Growth ◽

Optimal Incubation

In birds, incubation temperature has received increased attention as an important source of phenotypic variability in offspring. A lower than optimal incubation temperature may negatively affect aspects of nestling physiology, such as body growth and energy metabolism. However, the long-term effects of sub-optimal incubation temperature on morphology and physiology are not well understood. In a previous study, we showed that zebra finches from eggs incubated at a low temperature (35.9°C) for 2/3 of the total incubation time suffered a lower post-fledging survival compared to individuals that had been incubated at higher temperatures (37.0 and 37.9°C). In the present study, we investigated whether these variations in incubation temperature could cause permanent long-lasting differences in body mass, body size, or basal metabolic rate. Furthermore, we tested whether the observed differences in survival between treatment groups would be reflected in the rate of physiological deterioration, assessed through oxidative damage and decreased metabolic rate with age (i.e. ‘metabolic aging’). Incubation temperature did not significantly affect embryonic or nestling body growth and did not influence final adult body mass or body size. Nor was there any long-term effect on basal metabolic rate. Birds from eggs incubated at the lowest temperature experienced an accumulation of oxidative damage with age, although this was not accompanied by an accelerated rate of metabolic aging. The present results suggest that the low survival in these birds was possibly mediated by increased oxidative stress, but independent of body growth and the basal metabolic rate.

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Metabolic reduction after long-duration flight is not related to fat-free mass loss or flight duration in a migratory passerine

Journal of Experimental Biology ◽

10.1242/jeb.215384 ◽

2020 ◽

Vol 223 (19) ◽

pp. jeb215384

Author(s):

Alexander R. Gerson ◽

Joely G. DeSimone ◽

Elizabeth C. Black ◽

Morag F. Dick ◽

Derrick J. Groom

Keyword(s):

Metabolic Rate ◽

Mass Loss ◽

Body Mass ◽

Lean Mass ◽

Migratory Birds ◽

Resting Metabolic Rate ◽

Fat Free Mass ◽

Flight Duration ◽

Long Duration ◽

Resting Metabolism

ABSTRACTMigratory birds catabolize large quantities of protein during long flights, resulting in dramatic reductions in organ and muscle mass. One of the many hypotheses to explain this phenomenon is that decrease in lean mass is associated with reduced resting metabolism, saving energy after flight during refueling. However, the relationship between lean body mass and resting metabolic rate remains unclear. Furthermore, the coupling of lean mass with resting metabolic rate and with peak metabolic rate before and after long-duration flight have not previously been explored. We flew migratory yellow-rumped warblers (Setophaga coronata) in a wind tunnel under one of two humidity regimes to manipulate the rate of lean mass loss in flight, decoupling flight duration from total lean mass loss. Before and after long-duration flights, we measured resting and peak metabolism, and also measured fat mass and lean body mass using quantitative magnetic resonance. Flight duration ranged from 28 min to 600 min, and birds flying under dehydrating conditions lost more fat-free mass than those flying under humid conditions. After flight, there was a 14% reduction in resting metabolism but no change in peak metabolism. Interestingly, the reduction in resting metabolism was unrelated to flight duration or to change in fat-free body mass, indicating that protein metabolism in flight is unlikely to have evolved as an energy-saving measure to aid stopover refueling, but metabolic reduction itself is likely to be beneficial to migratory birds arriving in novel habitats.

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