Variation In Energy Requirements Research Articles

Great tits (Parus major) in a west European temperate forest show little seasonal variation in metabolic energy requirements

Understanding how birds annually allocate energy to cope with changing environmental conditions and physiological states is a crucial question in avian ecology. There are several hypotheses to explain species' energy allocation. One prominent hypothesis suggests higher energy expenditure in winter due to increased thermoregulatory costs. The "reallocation" hypothesis suggests no net difference in seasonal energy requirements, while the "increased demand" hypothesis predicts higher energy requirements during the breeding season. Birds are expected to adjust their mass and/or metabolic intensity in ways that are consistent with their energy requirements. Here, we look for metabolic signatures of seasonal variation in energy requirements of a resident passerine of a temperate-zone (great tit, Parus major). To do so, we measured whole-body and mass-independent basal (BMR), summit (Msum), and field (FMR) metabolic rates during late winter and during breeding in Belgian great tits. During the breeding season, birds had on average 10% higher whole-body BMR and FMR compared to winter, while their Msum decreased by 7% from winter to breeding. Mass-independent metabolic rates showed a 10% increase in BMR and a 7% decrease in Msum from winter to breeding. Whole-body BMR was correlated with Msum, but this relationship did not hold for mass-independent metabolic rates. The modest seasonal change we observed suggests that great tits in our temperature study area maintain a largely stable energy budget throughout the year, which appears mostly consistent with the reallocation hypothesis.

Osteometabolism: Metabolic Alterations in Bone Pathologies.

Renewing interest in the study of intermediate metabolism and cellular bioenergetics is brought on by the global increase in the prevalence of metabolic illnesses. Understanding of the mechanisms that integrate energy metabolism in the entire organism has significantly improved with the application of contemporary biochemical tools for quantifying the fuel substrate metabolism with cutting-edge mouse genetic procedures. Several unexpected findings in genetically altered mice have prompted research into the direction of intermediate metabolism of skeletal cells. These findings point to the possibility of novel endocrine connections through which bone cells can convey their energy status to other metabolic control centers. Understanding the expanded function of skeleton system has in turn inspired new lines of research aimed at characterizing the energy needs and bioenergetic characteristics of these bone cells. Bone-forming osteoblast and bone-resorbing osteoclast cells require a constant and large supply of energy substrates such as glucose, fatty acids, glutamine, etc., for their differentiation and functional activity. According to latest research, important developmental signaling pathways in bone cells are connected to bioenergetic programs, which may accommodate variations in energy requirements during their life cycle. The present review article provides a unique perspective of the past and present research in the metabolic characteristics of bone cells along with mechanisms governing energy substrate utilization and bioenergetics. In addition, we discussed the therapeutic inventions which are currently being utilized for the treatment and management of bone-related diseases such as osteoporosis, rheumatoid arthritis (RA), osteogenesis imperfecta (OIM), etc., by modulating the energetics of bone cells. We further emphasized on the role of GUT-associated metabolites (GAMs) such as short-chain fatty acids (SCFAs), medium-chain fatty acids (MCFAs), indole derivates, bile acids, etc., in regulating the energetics of bone cells and their plausible role in maintaining bone health. Emphasis is importantly placed on highlighting knowledge gaps in this novel field of skeletal biology, i.e., "Osteometabolism" (proposed by our group) that need to be further explored to characterize the physiological importance of skeletal cell bioenergetics in the context of human health and bone related metabolic diseases.

Seasonal variations in the feeding ecology of Nephrops norvegicus in the Adriatic Sea: insights from stomach contents and stable isotope analyses

Norway lobster Nephrops norvegicus is one of the most important commercial species in the Mediterranean. This study focused on its feeding ecology in an important fishing ground within the Adriatic Sea, using an integrated approach of stomach content (SCA) and stable isotope (SIA) analyses. The simultaneous use of these tools represents a modern and complete approach that provides reliable data over time and reflects the feeding strategy of the analysed species. Monthly sampling was carried out (January-December 2019, July and October 2020; 589 specimens) to investigate seasonal changes in diet and trophic level. Variations in fullness, gonadosomatic and hepatosomatic indices were analysed to explore changes in feeding and variations in energy requirements linked to reproductive needs. Results showed that N. norvegicus mostly prey on decapod crustaceans and fish. Seasonal variations in prey consumption were likely linked to the reproductive patterns of the species. SIA results confirmed SCA findings and placed N. norvegicus at a high position within the benthic food web. Overall, considering that the Adriatic Sea represents one of the most important and productive fishing areas for Norway lobster, this study provides critical information for an effective ecosystem approach to fisheries management of this resource.

Moringa oleifera leaf extract influences oxidative metabolism in C2C12 myotubes through SIRT1-PPARα pathway

BackgroundMoringa oleifera is an important traditional multipurpose plant, due to the presence of many bioactive compounds. Moringa oleifera leaf extracts (MOLE) have been shown to have many beneficial properties in pathological conditions including diabete. However, the lack of information about its exact molecular mechanism of action might hinder other potential use in different areas such as skeletal muscle physiology. Hypothesis/purposeSkeletal muscle represents about 40-50% of the total mass of a lean individual and is an insulin-sensitive tissue with wide variations in energy requirements. We aimed to test the effects of MOLE on oxidative metabolism and the molecular mechanism involved on myotubes by using C2C12 cell line, a well known model for in vitro skeletal muscle studies. Study designC2C12 myotubes were treated with MOLE at different working solutions for 24 and 48 hours and then culture media and cellular extracts were collected. MOLE was screened for phytochemicals determination. MethodsGlucose and free fatty acids consumption along with lactate release were assessed in the culture media. Citrate sinthase, 3-hydroxy acylCoA dehydrogenase, alanine transglutaminase and creatine kinase enzyme activities, as well as the metabolic regulatory SIRT1 and PPARα protein levels were evaluated in cellular extracts. ResultsMOLE administration induced a dose and time dependent increase in substrates consumption accompanied by an increase in intracellular oxidative metabolism enzymatic activity levels. The extracts were also able to modulate positively the protein expression of SIRT1 and PPARα. ConclusionAltogether, these data indicate that MOLE could represent a valid nutritional support for improving skeletal muscle metabolism: in fact MOLE treatment increased oxidative energy metabolism and possibly favours mitochondrial biogenesis through SIRT1/PPARα pathway. future studies will clarify wether Moringa oleifera leaf extracts consumption may be useful to improve physical performance and metabolic-related skeletal muscle diseases.

The role of physiological traits in assortment among and within fish shoals.

Individuals of gregarious species often group with conspecifics to which they are phenotypically similar. This among-group assortment has been studied for body size, sex and relatedness. However, the role of physiological traits has been largely overlooked. Here, we discuss mechanisms by which physiological traits—particularly those related to metabolism and locomotor performance—may result in phenotypic assortment not only among but also within animal groups. At the among-group level, varying combinations of passive assortment, active assortment, phenotypic plasticity and selective mortality may generate phenotypic differences among groups. Even within groups, however, individual variation in energy requirements, aerobic and anaerobic capacity, neurological lateralization and tolerance to environmental stressors are likely to produce differences in the spatial location of individuals or associations between group-mates with specific physiological phenotypes. Owing to the greater availability of empirical research, we focus on groups of fishes (i.e. shoals and schools). Increased knowledge of physiological mechanisms influencing among- and within-group assortment will enhance our understanding of fundamental concepts regarding optimal group size, predator avoidance, group cohesion, information transfer, life-history strategies and the evolutionary effects of group membership. In a broader perspective, predicting animal responses to environmental change will be impossible without a comprehensive understanding of the physiological basis of the formation and functioning of animal social groups.This article is part of the themed issue ‘Physiological determinants of social behaviour in animals’.

Between‐lake variation in the trophic ecology of an invasive crayfish

Abstract The trophic ecology of invasive species has important implications for their impacts on recipient ecosystems, with omnivorous invaders potentially affecting native species and processes over multiple trophic levels. The trophic ecology of invaders might be affected by both their body size and the characteristics of their habitat due to variation in energy requirements and resource availability. Here, using stable‐isotope analysis, we investigated the trophic ecology of the invasive crayfish Procambarus clarkii in 15 populations in southwest France over a gradient of individual (crayfish body size), population (crayfish abundance) and ecosystem (lake size, productivity and predation pressure) characteristics. We predicted that population niche width, level of omnivory and trophic position of individuals would change with abiotic and biotic conditions, but that these relationships would vary with lake size. The trophic position of individual crayfish increased with body size in lakes with low productivity, but decreased with body size in more productive lakes. As crayfish abundance increased (and therefore potential intraspecific competition), individual trophic position and population niche width decreased. This was most apparent in smaller lakes, suggesting it related to an increase in encounter rates with conspecifics. Body size, population abundance, lake size and lake productivity influenced the trophic ecology of invasive crayfish, which can affect their interactions with native species. Our results demonstrated that the trophic ecology of invasive species can be variable across invaded landscapes, with implications for their ecological impacts on native communities. This emphasizes the importance of characterising the diet of invasive species across their non‐native range and environmental gradients to better predict and manage their impacts.

Correlates of objectively measured physical activity in dogs

To increase physical activity (PA) levels in dogs and to better evaluate their energy requirements, there is a need to understand which factors or correlates are associated with PA and/or sedentary behaviour. Improving our understanding of these correlates also has implications for prescribed energy requirements in dogs. PA was measured using accelerometry in 62 dogs from two common breeds (Labrador retrievers and Cocker spaniels). Five potential correlates (age, sex, breed, neuter status, body condition score) were tested for associations with total volume of PA, light-moderate intensity PA, vigorous intensity PA and sedentary behaviour. Age and breed were associated with total volume of PA, light-moderate intensity PA and sedentary behaviour in the final models. Age was associated with vigorous intensity PA. The final models explained 60%, 40%, 63% and 44% of variance in total volume of PA, light-moderate intensity PA, vigorous intensity PA and sedentary behaviour, respectively. These results should improve understanding of the variation in energy requirements of dogs, as well as the development of age and breed-specific diets and the prevention and treatment of canine obesity.

Comparison of multiple and novel measures of dietary glycemic carbohydrate with insulin resistant status in older women

BackgroundPrevious epidemiological investigations of associations between dietary glycemic intake and insulin resistance have used average daily measures of glycemic index (GI) and glycemic load (GL). We explored multiple and novel measures of dietary glycemic intake to determine which was most predictive of an association with insulin resistance.MethodsUsual dietary intakes were assessed by diet history interview in women aged 42-81 years participating in the Longitudinal Assessment of Ageing in Women. Daily measures of dietary glycemic intake (n = 329) were carbohydrate, GI, GL, and GL per megacalorie (GL/Mcal), while meal based measures (n = 200) were breakfast, lunch and dinner GL; and a new measure, GL peak score, to represent meal peaks. Insulin resistant status was defined as a homeostasis model assessment (HOMA) value of >3.99; HOMA as a continuous variable was also investigated.ResultsGL, GL/Mcal, carbohydrate (all P < 0.01), GL peak score (P = 0.04) and lunch GL (P = 0.04) were positively and independently associated with insulin resistant status. Daily measures were more predictive than meal-based measures, with minimal difference between GL/Mcal, GL and carbohydrate. No significant associations were observed with HOMA as a continuous variable.ConclusionA dietary pattern with high peaks of GL above the individual's average intake was a significant independent predictor of insulin resistance in this population, however the contribution was less than daily GL and carbohydrate variables. Accounting for energy intake slightly increased the predictive ability of GL, which is potentially important when examining disease risk in more diverse populations with wider variations in energy requirements.

Oxidative modification and aggregation of creatine kinase from aged mouse skeletal muscle

Creatine kinase catalyzes the reversible transfer of the gamma phosphate from ATP to creatine forming the high energy compound creatine phosphate. Muscle creatine kinase (CKm) activity maintains energetic homeostasis as variations in energy requirements dictate that ATP be readily available. Recent studies suggest that CKm activity is altered during aging. Proteomic analyses have shown that CKm is 3-nitrotyrosine (3-NT) modified and carbonylated in aged rodent skeletal muscle. However, it remains unknown if these modifications affect its structure and activity. To address this we characterized oxidatively modified CKm from the quadriceps of young, middle-aged, and aged mice. Our data indicate that 3-NT modified and carbonylated CKm are found predominantly in aged muscle and that it exists in high molecular weight oligomers and insoluble protein aggregates. CKm from middle-aged and aged mouse quadriceps also exhibits structural instability that may account for its reduction in function. These structural and functional changes correlate with the differential protein modifications. Interestingly, the majority of the age-related changes in enzyme activity and protein stability occurred by middle age. Our studies indicate that the age-associated oxidative and nitrative modification of CKm results in a decrease in its activity and may cause structural changes that promote oligomerization and aggregation.

An analysis of cross-sectional variations in total household energy requirements in India using micro survey data

Using micro level household survey data from India, we analyse the variation in the pattern and quantum of household energy requirements, both direct and indirect, and the factors causing such variation. An econometric analysis using household survey data from India for the year 1993–1994 reveals that household socio-economic, demographic, geographic, family and dwelling attributes influence the total household energy requirements. There are also large variations in the pattern of energy requirements across households belonging to different expenditure classes. Results from the econometric estimation show that total household expenditure or income level is the most important explanatory variable causing variation in energy requirements across households. In addition, the size of the household dwelling and the age of the head of the household are related to higher household energy requirements. In contrast, the number of members in the household and literacy of the head are associated with lower household energy requirements.

Sexual activity and cardiovascular risk

For the majority of patients, sexual activity in a familiar and monogamous setting poses a very modest coronary risk; in fact, some epidemiological studies suggest longevity benefits for sexually active persons. Although the relative risk for myocardial infarction is increased during and within 2h after sex, the absolute risk remains minuscule. The metabolic and haemodynamic demands of sexual activity, as well as any cardiac rhythm disturbances observed during sex, are generally consistent with those of daily activities, although there is considerable inter-individual variation in energy requirements. Risk for myocardial infarction during sex can be reduced through exercise training, and exercise testing plays a central role in determining the risks associated with sexual activity and treatment for erectile dysfunction. Consensus guidelines have been released to assist the clinician in risk-stratifying patients with concomitant cardiovascular disease and erectile dysfunction, determining the advisability of resuming sexual activity or treatment for erectile insufficiency, and otherwise counselling the cardiac rehabilitation patient. Phosphodiesterase type 5 inhibitors can potentiate the blood pressure lowering effects of nitrates and nitric oxide donors; concomitant administration of these agents with sildenafil citrate and likely other phosphodiesterase type 5 inhibitors is contraindicated. (Eur Heart J Supplements 2002; 4 (Suppl H): H13‐H18)

Stochastic simulation of growth in pigs: relations between body composition and maintenance requirements as mediated through protein turn-over and thermoregulation

AbstractA dynamic model for simulation of growth in pigs, extended to describe thermoregulatory processes, was made stochastic to simulate groups of pigs with between-animal variation in mature body protein (Pα) and lipid mass (Lα), in the potential rate at which mature mass is attained (B⋆), and in the distribution of body protein and lipid over pools and depots. The resulting variation in body composition leads to variation in energy requirements for protein turn-over and thermoregulation, causing between-animal variation in maintenance requirements (MEmaint).Simulated population means for Pα, Lα/Pαand B⋆were varied in three steps each. Excluding unrealistic parameter combinations this led to 33 – 6 = 21 simulated genotypes. Simulated within-population coefficients of variation (CV) were 7, 15 and 3%. Random replicates of each genotype were simulated five times, in climatic conditions that were in turn severely cold, mildly cold (about 5 and 1ºC below lower critical temperature), thermoneutral, mildly hot and severely hot (about 1 and 5ºC above upper critical temperature), during the entire growth period of 23 to 100 kg live weight. Simulated food intake was ad libitum.Simulated thermoneutral within-population standard deviations of body protein and lipid content were 0·21 to 0·46 kg and 0·78 to 2·14 kg at 100 kg body weight. On average, the corresponding values in cold and hot conditions were slightly higher.MEmaintshowed a protein-turn-over-related within-population CV of 1·5% at thermoneutrality. Thermoregulatory action contributed about 4% extra variance in cold and hot conditions but CV values were not affected. A genetic increase in the maximum protein deposition rate from 100 to 250 g/day would increase MEmaintas related to protein turn-over and thermoregulation by 11% at thermoneutrality, and by 6 to 11% in cold or hot conditions. Two relevant groups of genotypes could be distinguished based on the within-population regression coefficients of MEmainton daily or cumulative protein deposition (bdailyPdep, bcumPdep). These ranged from 0·250 to 0·428 kJ/kg0·75 per day per g/day and from 2·77 to 5·45 kJ/kg0·75per day per kg, respectively, in 12 ‘conventional’ genotypes at thermoneutrality. On average, bdailyPdepwas increased by 48%, 20%, –11% and –36% in the other climatic conditions mentioned above, respectively. The corresponding increase of bcumPdepwas 32%, 14%, 8% and 48%. Three fast-growing lean genotypes showed similar bdailyPdepand bcumPdepat thermoneutrality, but much more pronounced increases in cold and hot conditions: 137%, 49%, –12% and + 88% for bdailyPdepand 248%, 108%, 17% and 196% for bcumPdep.It is concluded that differences in body composition traits between pig genotypes do not cause important between-genotype differences in thermoregulatory MEmaint, and that thermoregulatory processes contribute little body-composition-related variation to hot or cold MEmaintwithin most genotypes.The inferences to be made from this with regard to experimental design are discussed. The verification of the above predictions will require a very elaborate and large-scale experiment.

Choice of Foraging Area with Respect to Predation Risk in Redshanks: The Effects of Weather and Predator Activity

Animals often trade off risk of predation and risk of starvation when making foraging decisions. Redshanks, Tringa totanus, wintering in an area of high sparrowhawk, Accipiter nisus. predation were studied to determine how simultaneous variations in energy requirements and the risk of predation determine choice of foraging area. In particular, we focus on the effects of weather on this trade-off. Redshanks could either feed on a saltmarsh where both food availability and predation risk are high, or on safer, but less productive, inter-tidal flats. On the saltmarsh, redshanks could choose to feed in profitable but high risk areas close to cover or in lower risk creeks. In general, low temperatures resulted in birds using the saltmarsh habitat more, foraging closer to cover, and making less use of safe creek micro-habitats. This is consistent with low temperatures increasing redshanks' metabolic costs, thus increasing their preparedness to accept higher predation risk for greater foraging returns. At low temperatures sparrowhawks were more successful at catching redshanks, probably as a consequence of adoption of more risky foraging options by the redshanks, but rate of attack was probably not strongly affected by weather. Redshanks responded to precipitation by foraging in areas that reduced their predation risk. When precipitation was high, redshanks also became more prone to false alarm flights. These effects suggest that precipitation may increase predation risk by making the approach of a predator harder to detect. Redshanks foraged further from cover in high winds, suggesting that wind affected predation risk more than starvation risk. Redshanks responded strongly to sparrowhawk activity: use of the saltmarsh was less and redshanks foraged further from cover during days with a high attack frequency.

Advances in Dietary Management of Obesity in Dogs and Cats

Recent evidence in humans has reemphasized the importance of specific lifestyle behaviors such as activity level on energy requirements. A recent survey of adult pet dogs has shown a clear association between the level of activity and energy requirement, and suggests that current feeding recommendations may overestimate the energy requirements of adult dogs. Although a reduction in feeding guides may help to reduce the risk of overfeeding and subsequent development of obesity in adult dogs, there is considerable individual variation in energy requirements, which emphasizes the importance of tailoring feeding practices to the individual. Diet clearly has a critical role to play in both the prevention and treatment of obesity. We have evaluated the effect of different dietary regimens on the treatment of obesity in companion animals. In cats, increased energy restriction results in more rapid weight loss. However, this is associated with less favorable changes in body composition. In dogs, we have evaluated the potential benefit of insoluble and soluble dietary fiber on satiety in dogs that have been restricted to an energy intake appropriate for weight reduction. Results of a series of studies have failed to show any benefit of either fiber type on satiety in energy-restricted dogs.

From individual variation in energy intakes...to variations in energy requirements and adaptations to them

Dr Widdowson and Professor McCance always expressed a great deal of interest in the inter-individual variability in their scientific data considering that extreme values often provided the most revealing results. Their interest developed as a result of Dr Widdowson’s studies of the individual diets of men, women and children conducted in the 1930s; she later used the phrase ‘nutritional individuality’ to describe between-individual variability in intake and expenditure (Widdowson, 1962). This paper continues Dr Widdowson’s theme of individual variability. It focuses on recent data which describe between-individual differences in daily energy expenditure, particularly the extremes, and also on the insights these have given into the measurements of energy intake (EI).

From individual variation in energy intakes ... to variations in energy requirements and adaptations to them.

From individual variation in energy intakes ... to variations in energy requirements and adaptations to them.

Stochastic simulation of growth in pigs: protein turn-over-dependent relations between body composition and maintenance requirements

AbstractA dynamic model for simulation of growth in pigs, that was extended by a module to describe protein turn-over, was made stochastic in order to simulate groups of pigs with among-animal variation in the maximum daily protein deposition (Pdep, maxK in the minimum lipid to protein deposition rate (Ri/pimin), and in the distributionof body protein over protein pools (muscle, connective tissue, and other proteins). As a result, these simulated pigs show among-animal variation in body protein content and composition. This in turn leads to among-animal variation in energy requirements for protein turn-over and this causes among-animal variation in maintenance metabolizable energy requirements (MEmaint)as a result of variation in body composition.Simulated population means for PieVimax were varied in seven steps from 100 to 250 g/day, with an among-animal variation coefficient of 0·10; the feeding level was also varied in seven steps. Dependent on the levels of these input variables, 100-kg pigs showed within-population standard deviations in body protein and lipid content of 0·31 to 0·54 kg and 1·22 to 2·17 kg, respectively. ME showed a protein-turn-over-related, within-population coefficient of variation of 0·014 to 0·02. Comparisons over populations suggests that a 1·50 proportional increase in Pdep, max (from 100 to 250 g/day) would increase protein-turn-over-related MEmaint by 11 to 15%, from between 470 and 486 to 541 k] ME per kg body weight0'75 per day. The inferences that can be made from this with regard to experimental design are discussed.

Variation in energy requirements to maintain liveweight in pigs divergently selected for efficiency of lean growth

The energy requirement for maintenance in pigs has been suggested to be a function of liveweight (W), using equations such as 0.46 MJ digestible energy (DE)/g W0.75 (ARC, 1981). For a 60 kg pig, the predicted energy required for maintenance can proportionately account for 0.30 of the daily energy intake. Therefore, substantial reductions in pig production costs could be achieved, if the energy required for maintenance was reduced. The present study estimated the energy required to maintain liveweight, rather than the energy required for maintenance, as the latter assumes no change in protein or lipid content of the animal. Genotypes from the Edinburgh lean growth selection experiment provided the experimental resource to determine if selection for lean food conversion ratio over seven generations had changed the DE required to maintain liveweight.

Variation in energy requirements to maintain liveweight in pigs divergently selected for efficiency of lean growth

The energy requirement for maintenance in pigs has been suggested to be a function of liveweight (W), using equations such as 0.46 MJ digestible energy (DE)/g W0.75 (ARC, 1981). For a 60 kg pig, the predicted energy required for maintenance can proportionately account for 0.30 of the daily energy intake. Therefore, substantial reductions in pig production costs could be achieved, if the energy required for maintenance was reduced. The present study estimated the energy required to maintain liveweight, rather than the energy required for maintenance, as the latter assumes no change in protein or lipid content of the animal. Genotypes from the Edinburgh lean growth selection experiment provided the experimental resource to determine if selection for lean food conversion ratio over seven generations had changed the DE required to maintain liveweight.

Variations in function and design: Testing symmorphosis in the respiratory system

We explore the question of whether and to what extent the large variation in energy requirements observed among mammals is related to variations in the design of the respiratory system, from the lung to the mitochondria in muscle cells. Resting metabolic rate is determined by body size (allometric variation). Maximal rates of O 2 consumption (V̇ O2max) also vary in a regular manner with body size, but adaptive variation allows some species to achieve much higher values than others of the same body size. We, therefore, consider adaptive variation as modulation of structures and functions above those determined by allometric variation. A model is presented that separates functional and design parameters at four steps of the respiratory cascade: the pulmonary gas exchanger, heart and blood, microvasculature, and mitochondria. The variations observed in these parameters are analyzed with respect to those in energy demand and are discussed in relation to the hypothesis of symmorphosis. We conclude that the design of the internal steps of the respiratory system (mitochondria, capillaries, blood, and heart) is matched to functional demand, whereas the lung maintains a variable excess of morphometric diffusing capacity which may be related to the facts that the lung has limited malleability and that it forms the interface with the environment.