Heat increment of feeding and its thermoregulatory benefit in the muskrat (Ondatra zibethicus)

MacArthur, Robert A.; Campbell, Kevin L.

doi:10.1007/bf00301656

Cited by 34 publications

(21 citation statements)

References 17 publications

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“…A value of 3.0 was finally selected because it minimised r 2 . Within the range 2.0-4.0, Q 10 has a quantifiable effect on the scaling exponent Lusk (1915), Brody (1945), Gallivan and Ronald (1981), Costa and Kooyman (1984), Diamond et al (1985), McDonald et al (1988), MacArthur and Campbell (1994), Markussen et al (1994), Rosen and Trites (1997), Sherwood (1997), Clements et al (1998), Campbell et al (1999. .94, N=571.…”

Section: Body Temperaturementioning

confidence: 99%

Allometric scaling of mammalian metabolism

White

Seymour

2005

Journal of Experimental Biology

367

291

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SUMMARY The importance of size as a determinant of metabolic rate (MR) was first suggested by Sarrus and Rameaux over 160 years ago. Max Rubner's finding of a proportionality between MR and body surface area in dogs (in 1883) was consistent with Sarrus and Rameaux's formulation and suggested a proportionality between MR and body mass (Mb) raised to the power of 2/3. However, interspecific analyses compiled during the first half of the 20th century concluded that mammalian basal MR (BMR, ml O2 h-1) was proportional to Mb3/4, a viewpoint that persisted for seven decades, even leading to its common application to non-mammalian groups. Beginning in 1997, the field was re-invigorated by three new theoretical explanations for 3/4-power BMR scaling. However, the debate over which theory accurately explains 3/4-power scaling may be premature, because some authors maintain that there is insufficient evidence to adopt an exponent of 3/4 over 2/3. If progress toward understanding the non-isometric scaling of BMR is ever to be made, it is first essential to know what the relationship actually is. We re-examine previous investigations of BMR scaling by standardising units and recalculating regression statistics. The proportion of large herbivores in a data set is positively correlated both with the scaling exponent(b, where BMR=aMbb) and the coefficient of variation (CV: the standard deviation of ln-ln residuals) of the relationship. Inclusion of large herbivores therefore both inflates b and increases variation around the calculated trendline. This is related to the long fast duration required to achieve the postabsorptive conditions required for determination of BMR, and because peak post-feeding resting MR (RMRpp) scales with an exponent of 0.75±0.03 (95%CI). Large herbivores are therefore less likely to be postabsorptive when MR is measured, and are likely to have a relatively high MR if not postabsorptive. The 3/4 power scaling of RMRpp is part of a wider trend where,with the notable exception of cold-induced maximum MR(b=0.65±0.05), b is positively correlated with the elevation of the relationship (higher MR values scale more steeply). Thus exercise-induced maximum MR (b=0.87±0.05) scales more steeply than RMRpp, field MR (b=0.73±0.04), thermoneutral resting MR (RMRt, b=0.712±0.013) and BMR. The implication of this observation is that contamination of BMR data with non-basal measurements is likely to increase the BMR scaling exponent even if the contamination is randomly distributed with respect to Mb. Artificially elevated scaling exponents can therefore be accounted for by the inclusion of measurements that fail to satisfy the requirements for basal metabolism, which are strictly defined (adult,non-reproductive, postabsorptive animals resting in a thermoneutral environment during the inactive circadian phase). Similarly, a positive correlation between Mb and body temperature(Tb) and between Tb and mass-independent BMR contributes to elevation of b. While not strictly a defined condition for the measurement of BMR, the normalisation of BMR measurements to a common Tb (36.2°C) to achieve standard metabolic rate (SMR) further reduces the CV of the relationship. Clearly the value of the exponent depends on the conditions under which the data are selected. The exponent for true BMR is 0.686 (±0.014), Tb normalised SMR is 0.675 (±0.013) and RMRt is 0.712 (±0.013).

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Section: Body Temperaturementioning

confidence: 99%

Allometric scaling of mammalian metabolism

White

Seymour

2005

Journal of Experimental Biology

367

291

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“…O∑ were obtained from fasted muskrats at thermoneutrality (15±0.5°C) using positive pressure, open-circuit respirometry (MacArthur and Campbell, 1994). Short-term (15 min) diving trials were conducted in a fibreglass-lined, plywood tank (183 cm×175 cm×72 cm) housed in a controlled-environment room.…”

Section: Metabolic and Behavioural Recordings In Air And Watermentioning

confidence: 99%

Diving experience and the aerobic dive capacity of muskrats: does training produce a better diver?

MacArthur

Weseen

Campbell

2003

Journal of Experimental Biology

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SUMMARY We tested the hypothesis that the body oxygen stores, aerobic dive limit(ADL) and dive performance of muskrats can be enhanced by dive-conditioning in a laboratory setting. We compared several key variables in 12 muskrats trained to swim a 16 m underwater course to a feeding station (`divers') with those of 12 animals precluded from diving but required to travel identical distances in water to feed (`surface swimmers'). Acclimated muskrats assigned to each group were trained concurrently over a 9–11 week period. We observed significant gains in the haematocrit (P=0.0005) and blood haemoglobin concentration (P=0.015) of `divers', but not `surface swimmers'. The post-training blood O2 store calculated for `divers' (22.9 ml O2 kg–1) was nearly 26% higher than that (18.2 ml O2 kg–1) derived for `surface swimmers'(P=0.03). Dive-conditioning had no apparent effect on lung volume,whole blood and plasma volumes, nor on the glycogen level and buffering capacity of skeletal muscles. Cardiac and skeletal muscle myoglobin levels were also similar in both test groups following training. The mean total body oxygen store of `divers' (37.8ml O2 STPD kg–1) was 13.5% higher (P=0.037) than for `surface swimmers' (33.3 ml O2 STPD kg–1), an increase attributed entirely to the gain in blood O2 storage capacity of the former group. However,owing to a slightly higher estimate of diving metabolic rate in dive-conditioned animals, the calculated ADL for this group (61.3 s) was indistinguishable from that of `surface swimmers' (61.8 s). Few differences were observed in the post-training dive behaviour of `surface swimmers' and`divers', a finding consistent with the strong similarity in their calculated aerobic dive capacities.

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“…Ultimately, though, the functional significance and the exact nature of SDA are still unclear (Blaxter 1989). What is accepted, however, is that the energy utilized in SDA can be as much as 40%-50% of the metabolizable energy of ingested food (MacArthur and Campbell 1994;Jensen et al 1999) and, as a result, represents a substantial proportion of the energy budget of free-ranging animals.…”

Section: Introductionmentioning

confidence: 99%

Physiological Response to Feeding in Little Penguins

Green¹,

Frappell²,

Butler³

2006

Physiological and Biochemical Zoology

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Specific dynamic action (SDA), the increase in metabolic rate above resting levels that accompanies the processes of digestion and assimilation of food, can form a substantial part of the daily energy budget of free-ranging animals. We measured heart rate (f H ) and rate of oxygen consumption ( ) in 12 littlė Vo 2 penguins while they digested a meal of sardines in order to determine whether they show specific dynamic action. In contrast to some studies of other penguin species, little penguins showed a substantial SDA, the magnitude of which was proportional to the size of the meal. The energy utilized in SDA was equivalent to 13.4% of the available energy content of the fish. Furthermore, animals such as penguins that forage in a cold environment will probably expend further energy in heating their food to body temperature to facilitate efficient digestion. It is estimated that this additional energy expenditure was equivalent to 1.6%-2.3% of the available energy content of the fish, depending on the time of year and therefore the temperature of the water. Changes in f H during digestion were qualitatively similar to those in , implying that there were nȯ Vo 2 substantial circulatory adjustments during digestion and that the relationship between f H and in penguins is unaffecteḋ Vo 2 by digestive state.

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Heat increment of feeding and its thermoregulatory benefit in the muskrat (Ondatra zibethicus)

Cited by 34 publications

References 17 publications

Allometric scaling of mammalian metabolism

Allometric scaling of mammalian metabolism

Diving experience and the aerobic dive capacity of muskrats: does training produce a better diver?

Physiological Response to Feeding in Little Penguins

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