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The estimation of energy expenditure is key to resolve ecological questions and conservation strategies. The puma (Puma concolor (Linnaeus, 1771)) has been the subject of several efforts to measure the daily energy expenditure (DEE). Most of the estimations have been made using movement or activity models that have been questioned because of discrepancies with kill rates. This study looks at one movement model estimation and validates it using doubly labeled water (DLW), which can also account for energy expenditures beyond those associated with activity. We captured six pumas (51.5 [+ or -] 9.9 (SD) kg) during the winter in Colorado that were GPS collared and injected with DLW for an approximately 3-week trial. We found that DEE obtained from the DLW (14.5 [+ or -] 6.1 MJ*[day.sup.-1]) did not differ from that estimated using the movement model or from the predicted allometric equation based on DLW studies on other mammals. Decreasing air temperature and increasing daily distance movement were correlated with increasing DEE for monitored pumas. Both DLW and movement models provide a reasonable proxy to estimate DEE at the population level but exhibit low precision in estimating individual values for free-ranging puma. Key words: doubly labeled water, energetic expenditure, felids, field metabolic rate, mountain lion, Puma concolor, thermogenesis, Introduction Quantifying energetics provides a portal to understand how physiological, morphological, and behavioral traits of organisms optimize energy budgets on ontogenetic or evolutionary scales (Hedenstrom 2008). Evaluation of the daily [...]

Author(s): Diana M. Thomas [sup.1] , Krista Watts [sup.1] , Sara Friedman [sup.2] , Dale A. Schoeller [sup.2] Author Affiliations: (1) Department of Mathematical Sciences, United States Military Academy, West [...], Background/objectives Accurately predicting energy requirements form a critical component for initializing dynamic mathematical models of metabolism. The majority of such existing estimates rely on linear regression models that predict total daily energy expenditure (TDEE) from age, gender, height, and body mass, however, there is evidence these predictors obey a power function. Subjects/methods Baseline, free-living TDEE measured by doubly labeled water (DLW) in 20 studies with no overlapping subjects were obtained from the core lab at the University of Chicago and the University of Wisconsin-Madison (N = 2501 adults, 628 males, 1873 females). Linear regression models of log-transformed equations of the form: [Formula omitted] and [Formula omitted] were developed to determine the values of the exponents of body mass (M (kg)) and height (H (cm)) along with a gender effect (Sex). A nonlinear curve fit was performed to develop a power model that also includes age [Formula omitted]. Results The power for body mass, [beta].sub.1 = 0.45 and the power for height was [beta].sub.2 = 1.52 in the database with both genders combined. Adding gender reduced these to [beta].sub.1 = 0.43 and [beta].sub.2 = 1.04. All terms were significant (p < 0.01) except for height when including gender. The powers for height in the additive gender-specific models were both closer to 1 and the power for body mass was similar across all models ranging between 0.41 and 0.57. Conclusions A nonlinear scaling relationship was found to hold for body mass and needs to be considered when adjusting TDEE for body mass or predicting human energy requirements as a function of body mass especially in individuals with obesity.

Mammalian homologues of YiiP are responsible for zinc sequestration into secretory vesicles, thus playing important roles in neurotransmission (11) and hormone secretion (12). Zinc efflux catalysed by YiiP is coupled [...], The proton gradient is a principal energy source for respiration-dependent active transport, but the structural mechanisms of proton-coupled transport processes are poorly understood. YiiP is a proton-coupled zinc transporter found in the cytoplasmic membrane of Escherichia coli Its transport site receives protons from water molecules that gain access to its hydrophobic environment and transduces the energy of an inward proton gradient to drive Zn(II) efflux (1,2). This membrane protein is a well- characterized member (3-7) of the family of cation diffusion facilitators that occurs at all phylogenetic levels (8-10). Here we show, using X-ray-mediated hydroxyl radical labelling of YiiP and mass spectrometry, that Zn(II) binding triggers a highly localized, all-or-nothing change of water accessibility to the transport site and an adjacent hydrophobic gate. Millisecond time-resolved dynamics reveal a concerted and reciprocal pattern of accessibility changes along a transmembrane helix, suggesting a rigid-body helical re-orientation linked to Zn(II) binding that triggers the closing of the hydrophobic gate. The gated water access to the transport site enables a stationary proton gradient to facilitate the conversion of zinc-binding energy to the kinetic power stroke of a vectorial zinc transport. The kinetic details provide energetic insights into a proton-coupled active-transport reaction.

The purpose was to compare a mathematical model of oxygen uptake and bioenergetic systems to an experimental protocol. Twelve (N = 12) noncyclists (NC), age (21.8 [+ or -] 1.4 years), and 8 (N = 8) cyclists (C), age (30.5 [+ or -] 5.7 years), were subjects. All subjects signed an informed consent. Oxygen consumption ([[??]o.sub.2], ml x [kg.sup.-1] x [min.sup.-1]) was measured with steady-state [[??]o.sub.2] requirements and responses determined using the mathematical model from the following equation: [[??]o.sub.2] (WR) = [[??]o.sub.2] (rest) + [[??]o.sub.2] (unloading pedaling) + [alpha]. WR; [MATHEMATICAL EXPRESSION NOT REPRODUCIBLE IN ASCII]. Exercise means (SD) included the following: [[??]o.sub.2]NC(WR)=48.4 (16.6)[ml.sup.-1]. [min.sup.-1] for NCs and [[??]o.sub.2]C(WR)=56.4(24.95) [ml.sup.-1] x [min.sup.-1] for Cs; [DELTA][[??]o.sub.2]NC(t, WR)=6.38 [ml.sup.-1] x [min.sup.-1] for NCs and [DELTA][[??]o.sub.2]C(t, WR)=7.44 [ml.sup.-1] x [min.sup.-1] for Cs. The correlation between the mathematical model and actual measure was statistically significant (p < 0.01) with a coefficient of r = 0.947. The experimental protocol was significantly associated with the mathematical model. This allows for a quantitative analysis and safe prediction of steady-state oxygen uptake conditions on populations before exposure to exercising conditions. Through more precise analysis of conditions, greater specificity of training may lead to more predictable adaptation outcomes. KEY WORDS bioenergetic systems, prediction equation, oxygen capacity

Simultaneous equations have become increasingly popular for describing the effects of nutrition on the utilization of ME for protein (PD) and lipid deposition (LD) in animals. The study developed a multivariate nonlinear mixed effects (MNLME) framework and compared it with an alternative method for estimating parameters in simultaneous equations that described energy metabolism in growing pigs, and then proposed new PD and LD equations. The general statistical framework was implemented in the NLMIXED procedure in SAS. Alternative PD and LD equations were also developed, which assumed that the instantaneous response curve of an animal to varying energy supply followed the law of diminishing returns behavior. The Michaelis-Menten function was adopted to represent a biological relationship in which the affinity constant (k) represented the sensitivity of PD to ME above maintenance. The approach accommodated inclusion of a PD potential ([PD.sub.potential]) concept. This was described by a Gompertz function, which was parameterized in terms of the maximum rate of PD ([PD.sub.Max]) and corresponding BW ([BW.sub.PDMaz]) at that point. Metabolizable energy for LD was equated to the difference between ME intake and the sum of ME used for maintenance and PD. Metabolizable energy designated for PD and LD was used, with efficiencies [k.sub.p] and [k.sub.f], respectively. The new equations were compared with the van Milgen and Noblet (1999) equations using 2 comprehensive data sets on energy metabolism in growing pigs. The 2 equation sets were evaluated using information criteria, which showed that the new equations performed best for data set II, whereas the reverse was true for the first. For the data set I population, estimates for [k.sub.p] and [k.sub.f] were 0.57 (SE = 0.05) and 0.84 (SE = 0.03), respectively. Maintenance was quantified as 1.10 (SE = 0.08) MJ/d x [kg.sup.0.55]. The animal variation in the parameter kp was estimated to be 6% CV. The animal variation in [PD.sub.Max] and [k.sub.f] was estimated to be 9 and 10% of the population estimates, respectively. It was concluded that application of the MNLME framework was superior to the multivariate nonlinear regression model because the MNLME method accounted for correlated errors associated with PD and LD measurements and could also include the random effect of animal. It is recommended that multivariate models used to quantify energy metabolism in growing pigs should account for animal variability and correlated measurement errors. Key words: animal variability, energy metabolism, growth, multivariate nonlinear mixed effects modeling doi: 10.2527/jas.2009-2065

Diverse fish assemblages should feature a range of biological and ecological responses to temperature change. Using preliminary bioenergetics models, I simulated growth and maturation of three California Current groundfish (yelloweye rockfish (Sebastes ruberrimus), sablefish (Anoplopoma fimbria), and spiny dogfish (Squalus acanthias)) at fixed temperatures ranging from 5 [degrees]C to 11 [degrees]C. I examined three response variables (size at age 1 ([W.sub.1]), age at 50% maturity ([[tau].sub.50%]), and total prey consumption (C)). Yelloweye rockfish responded most strongly for [W.sub.1], which increased 496% as temperature increased from 5 [degrees]C to 11 [degrees]C. Spiny dogfish [[tau].sub.50%] was highly sensitive, declining from >48 years at 5 [degrees]C to Les peuplements diversifies de poissons devraient faire montre d'une gamme de reactions biologiques et ecologiques variees au changement de temperature. Des modeles bioenergetiques preliminaires m'ont permis de simuler la croissance et la maturation chez trois poissons de fond du courant de la Californie (le sebaste a yeux jaunes (Sebastes ruberrimus), la morue charbonniere (Anoplopoma fimbria) et l'aiguillat commun (Squalus acanthias)) a des temperatures fixes entre 5 [degrees]C et 11 [degrees]C. Trois variables de reaction ont ete examinees, la taille a l'age 1 ([W.sub.1]), l'age a 50 % de maturite ([tau].sub.50%]) et la consommation totale de proies (C). Les sebastes aux yeux jaunes reagissent le plus fortement en ce qui a trait a [W.sub.1] qui a augmente de 496% lorsque la temperature est passee de 5 [degrees]C a 11 [degrees]C. Le [[tau].sub.50%] des aiguillats communs est tres sensible, ayant diminue de >48 ans a 5 [degrees]C a 5 fois sur la gamme de temperatures, bien que les morues charbonnieres aient vraisemblablement un plus grand impact au niveau de la communaute dans son ensemble a cause de leur niveau trophique et de leurs taux absolus d'alimentation plus eleves. Les changements de regime, les anomalies thermiques ou le changement climatique global peuvent affecter directement les bilans energetiques des poissons, entrainant des changements de repartition ou produisant des interactions ecologiques complexes. Des etudes comme celle-ci aideront les gestionnaires a identifier les especes sensibles a la temperature et a anticiper les changements potentiels dans les populations et les communautes diversifiees. [Traduit par la Redaction], Introduction Temperature plays a central role in the biology of fishes. A considerable body of research has focused on the effect of temperature on fish feeding, growth, and reproductive rates [...]

Development of quantitative tools to characterize the nature of predator-prey interactions is an essential component of the science supporting ecosystem-based management and conservation. A common constraint is our capacity to estimate the feeding rates of fishes at the temporal and spatial scales at which predation occurs. This study developed a new field-based modeling approach for estimating consumption rates of large predatory fishes that requires fewer assumptions and may be more flexible than other field-based methods. We compared the field-based model results with consumption estimates from a bioenergetics model for lingcod (Ophiodon elongatus), a top predator in nearshore rocky habitats along the west coast of North America. The models were used to determine population-level consumption of rockfishes (Sebastes spp.) by lingcod in marine reserves and nonreserve areas in the San Juan Channel, Washington, USA. Based on these models, rockfish consumption by lingcod may have been 5-10 times greater in marine reserves than in nonreserves during fall and summer, 2005-2007. Understanding whether lingcod predation may limit the efficacy of marine reserves for rockfish recovery requires site-specific information on the abundance and size structure of lingcod and rockfishes. La mise an point d'outils quantitatifs pour caracteriser la nature des interactions predateurs-proies est un element essentiel des bases scientifiques sur lesquelles s'appuient la gestion et la conservation centrees sur les ecosystemes. Un obstacle courant est la necessite d'estimer les taux d'alimentation des poissons aux echelles temporelles et spatiales auxquelles se produit la predation. Notre etude a developpe une approche de modelisation basee sur le terrain pour estimer les taux de consommation des grands poissons predateurs qui necessite un moins grand nombre de presuppositions et qui est pent-etre plus flexible que les autres methodes basees sur le terrain. Nous comparons les resultats de notre modele base sur le terrain aux consommations estimees par un modele bioenergetique chez la morue-lingue (Ophiodon elongatus), un predateur superieur dans les habitats rocheux littoraux le long de la cote occidentale de l'Amerique du Nord. Les modeles ont servi a determiner la consommation de sebastes (Sebastes spp.) an niveau de la population par les morues-lingues dans des reserves marines et hors des reserves dans le chenal de San Juan, Washington, E.-U. D'apres ces modeles, la consommation de sebastes par les morues-lingues a pu etre plus elevee par un facteur de 5-10 dans les reserves marines que hors des reserves durant l'automne et l'ete en 2005-2007. Pour comprendre si la predation par les morues-lingues pent limiter l'efficacite des reserves marines dans le retablissement des populations de sebastes, il sera necessaire d'obtenir des informations specifiques aux sites sur l'abondance et la structure en taille des morues-lingues et des sebastes. [Traduit par la Redaction], Introduction Ecosystem-based management of marine resources requires the development of modeling and empirical approaches for quantifying ecological interactions (Francis et al. 2007) and elucidating potential trade-offs in multispecies management and [...]

Skeletal muscle plays a major role in the regulation of whole-body energy metabolism during physiological stresses such as ischemia, hypoxia, and exercise. Current experimental techniques provide relatively little in vivo data on dynamic responses of metabolite concentrations and metabolic fluxes in skeletal muscle to such physiological stimuli. As a complementary approach to experimental measurements and as a framework for quantitatively analyzing available in vivo data, a physiologically based model of skeletal muscle cellular metabolism and energetics is developed. This model, which incorporates key transport and reaction processes, is based on dynamic mass balances of 30 chemical species in capillary (blood) and tissue (cell) domains. The reaction fluxes in the cellular domain are expressed in terms of a generalized Michaelis-Menten equation involving energy controller ratios ATP/ADP and NADH/NA[D.sup.+]. This formalism introduces a large number of unknown parameters (~ 90). Estimating these parameters from in vivo sparse data and evaluating dynamic sensitivities of the model outputs with respect to these parameters is a challenging problem. Parameter estimation is accomplished using an efficient, nonlinear, constraint-based, optimization algorithm that minimizes differences between available experimental data and corresponding model outputs by explicitly utilizing equality constraints on resting fluxes and concentrations. With the estimated parameter values, the model is able to simulate dynamic responses to reduced blood flow (ischemia) of key metabolite concentrations and metabolic fluxes, both measured and nonmeasured. A general parameter sensitivity analysis is carried out to determine and characterize the parameters having the most and least effects on the measured outputs. Index Terms--Mathematical modeling; computer simulation; dynamic mass balances; skeletal muscle; cellular metabolism; ischemia; optimal parameter estimation; sensitivity analysis.

A novel water budget model was developed for the theoretical calculation of energy retention and other energy budget components in free-living animals based on the doubly labeled water (DLW) method. The DLW-based water budget model utilizes CO2 production, water influx and dietary habits to estimate energy expenditure, metabolizable energy intake and body energy balance in free-living animals. Furthermore, body mass change was not utilized in the model because animals that lose body mass can be in positive energy balance.

A mathematical model of lactating sow metabolism was evaluated using three types of tests. First, 16 experimental treatments from four experiments reported in the literature were simulated with the model, and the simulated values for change in BW and protein and fat content were compared to reported or calculated values. Second, the model's response to level of feed intake, level of milk production, BW and composition at farrowing, and dietary lysine concentration was compared to expected responses. Third, the model's sensitivity to changes in several of its kinetic parameters was measured. There was good agreement between simulated and measured values for BW and fat loss and reasonable agreement for body protein loss. All responses to changes in external conditions were in expected directions and biologically reasonable. The model seemed rather robust with respect to changes in the kinetic parameters considered, although important changes in simulated values were found in some cases. Overall, the model seems sound. It can be useful in evaluation of feeding programs and in understanding biological relationships.

An energy-based model for carrying capacity of quails is presented and applications for the model in wildlife management are suggested. The carrying capacity model can be used to estimate the usefulness of food management on a particular area and also to provide decision-support information for management planning.

Research was conducted to examine the factors that contribute to energy expenditure during cycling using ergometer tests. The first includes factors related to rider characteristics including sex, age, weight and training level. The second includes factors related to cycling techniques. The third pertains to factors related to environmental aspects such as humidity and temperature. The fourth includes components of the cycle itself. Results indicate that the most influential factors contributing to caloric consumption are pedal frequency and force.