Differences In Energy Requirements Research Articles

Energy requirement for primiparous Holstein × Gyr crossbred dairy cows

Our objective was to estimate the requirements of metabolizable energy (ME) and net energy for the maintenance (NEm) of lactating and dry cows, the efficiency of ME utilization for milk production (kl) and tissue gain (kg), and the use of body energy mobilization for milk production (kt) throughout the lactation of primiparous crossbred Holstein × Gyr cows, using open-circuit respiration chambers. Twenty-nine primiparous Holstein × Gyr crossbred cows with an initial BW averaging 563 ± 40.1 kg and 2.5 ± 0.09 years old were used throughout lactation and dry periods. The cows were kept non-pregnant throughout the study to eliminate possible confounding factors. Apparent digestibility assays, followed by calorimeter measurements, were performed 6 times throughout the lactation period. In the dry-off period, the cows were also evaluated but fed with restricted intake (DMI = 1.1% BW/d) to achieve heat production close to maintenance. After 21 d of diet adaptation, an apparent digestibility assay followed by calorimeter measurements was performed. Parameter estimates for lactation period were obtained by mixed models including lactation stage as repeated measures. For restricted feeding at dry-off and fasting period assays, the requirements were estimated by exponential regression. For whole lactation, the values of MEm and NEm were 0.588 and 0.395 MJ/BW0.75, respectively. The efficiencies klkgkt were 0.672, 0.771, and 0.814, respectively. However, MEm and NEm were higher in early and mid-lactation than late, while kl was higher in early than other lactation stages. Dry and non-pregnant cows had MEm of 0.434 MJ/BW0.75 and NEm of 0.351 MJ/BW0.75 for maintenance level, and MEm of 0.396 MJ/BW0.75 and NEm of 0.345 MJ/BW0.75 for fasting metabolism level and efficiency of ME utilization for maintenance was 0.80. Our findings confirmed that F1 crossbred Holstein × Gyr dairy cows have differences in energy requirement and efficiency throughout the lactation stages, suggesting the use of different values in each stage. The estimated values of energy requirement for maintenance and efficiencies for primiparous lactating crossbred Holstein × Gyr were similar to those reported in the literature in specific studies and requirements systems.

Among-individual variation in thermal plasticity of fish metabolic rates causes profound variation in temperature-specific trait repeatability, but does not co-vary with behavioural plasticity.

Conspecifics of the same age and size differ consistently in the pace with which they expend energy. This among-individual variation in metabolic rate is thought to influence behavioural variation, since differences in energy requirements should motivate behaviours that facilitate energy acquisition, such as being bold or active in foraging. While there is evidence for links between metabolic rate and behaviour in constant environments, we know little about whether metabolic rate and behaviour change together when the environment changes-that is, if metabolic and behavioural plasticity co-vary. We investigated this using a fish that becomes dormant in winter and strongly reduces its activity when the environment cools, the cunner (Tautogolabrus adspersus). We found strong and predictable among-individual variation in thermal plasticity of metabolic rates, from resting to maximum levels, but no evidence for among-individual variation in thermal plasticity of movement activity, meaning that these key physiological and behavioural traits change independently when the environment changes. The strong among-individual variation in metabolic rate plasticity resulted in much higher repeatability (among-individual consistency) of metabolic rates at warm than cold temperatures, indicating that the potential for metabolic rate to evolve under selection is temperature-dependent, as repeatability can set the upper limit to heritability. This article is part of the theme issue 'The evolutionary significance of variation in metabolic rates'.

Hard life for sons in the nest? Sex-dependent offspring mortality in Great Tits in urban and forest areas

Sex-biased mortality can occur in birds during development, for example due to sexual differences in energy requirement and/or environmental sensitivity, or the effects of sex hormones or sex differences in the expression of mutations linked to sex chromosomes. The extent of sex-bias in mortality may also be related to environmental conditions that influence offspring development and survival. Urban areas often provide poorer conditions for nestling development resulting in higher offspring mortality compared to natural areas, which may accelerate sex differences in offspring mortality in cities. To test this hypothesis, we examined the sex ratio of dead offspring in Great Tits (Parus major), using 427 samples of unhatched eggs and dead nestlings collected in two urban and two forest sites between 2013 and 2019. The ratio of males in the whole sample of dead offspring (56.9%) was significantly higher than expected by an 1:1 ratio, and the strongest sex biases were detected in urban areas (57.6% males) and in young nestlings (<14 days old, 59.0% males). However, the sex ratios of dead offspring did not differ significantly among study sites and between offspring developmental stages. 29.3% of unhatched eggs contained a visible embryo, and the proportion of embryo-containing unhatched eggs did not differ significantly between urban and forest study sites. These results suggest male-biased offspring mortality in Great Tits, and highlight the need of large datasets to detect subtle differences between habitats and developmental stages.

328 Comparison of Predicted Nutritional Requirements of Two Feeding Systems for Dairy Cattle Implemented in a Monte-Carlo Simulation Model of Herd Dynamics

Abstract There is increased interest in precision-feeding systems that account for individual-animal variation and temporal dairy herd dynamics to increase feed-efficiency and reduce environmental footprints. The Ruminant Farm Systems (RuFaS; Hansen et al., 2021) model simulates individual animals on a daily timestep using a stochastic, Monte Carlo framework to represent the phenotypic diversity and population dynamics expected in a dairy herd. Within RuFaS, individual animal nutrient requirements are used to inform pen-level diet formulations and feed delivery. However, nutritional requirements for feeding dairy cattle were recently updated via consideration of both animal and diet-related factors. Our aim was to calculate individual animal predictions for dry matter intake (DMI), as well as energy and metabolizable protein requirements, and compare the methods described in the 7th (NRC, 2001) and 8th (NASEM, 2021) editions of the Nutrient Requirements for Dairy Cattle. For that purpose, we simulated dairy herds (ca. 6,000 individual Holstein animals per simulation, mean adult body weight = 671 kg, standard deviation = 79, mean daily milk production = 39.8 kg·day-1·cow-1 , standard deviation = 7.5) for 10+ year time periods with an updated version of RuFaS. The simulated herds provided a wide range of values with which to test the nutrient requirement models, and their implications. The NASEM DMI estimates were less across the board but began to converge towards NRC calculated values at the larger simulated animal body weights. The principal differences in energy requirements between the two models (NRC vs. NASEM) were: 1) predicted requirements for pregnancy were significantly greater for NASEM than NRC across all life history stages; 2) NASEM displayed slightly greater energy requirements for growth in first and second lactation cows, and; 3) NASEM predicted decreased maintenance requirements for all heifer stages but the opposite was true for mature cows. Metabolizable protein requirements were greater following NASEM calculations in heifers over 300 kg, but strikingly similar to NRC-computed values for lactating cows. Overall, results from this modeling study align with our expectations and demonstrate successful implementation of the two nutrition models within the RuFaS model. These outputs confirm the usefulness of data obtained to explore applications of the two nutrient requirement models under different precision feeding management practices and, to some extent, to quantitatively evaluate their viability of the models in edge cases that can occur within the expected variation of a herd’s population. Future work will explore downstream consequences of the nutrient requirement models within the automated, least-cost ration formulation framework using nonlinear programming and metrics related to manure output and storage. These data will guide further developments of RuFaS as whole farm simulation model and provide insights into expected variation in nutritional requirements within a dynamic set of animals.

Size and body condition of sympatric killer whale ecotypes around the Antarctic Peninsula

Killer whales Orcinus orca are apex predators, and their health can indicate trophic dynamics in ecosystems that support them. We used aerial photogrammetry to estimate body lengths, to better understand size differences and food requirements, and widths, to infer current nutritional condition, of killer whales in the rapidly warming waters around the Antarctic Peninsula. A remotely controlled hexacopter drone was used to collect aerial images of 242 killer whales of 3 sympatric ecotypes (Type A, n = 34; Type B1, n = 19; and Type B2, n = 189) in the austral summers between 2015/2016 and 2018/2019. Total length (TL) varied between ecotypes, with B2s being diminutive in size, indicating large differences in energy requirements. The mean length for adult females ranged from 5.82 m (B2s) to 6.93 m (B1s), and the mean for adult males ranged from 6.44 m (B2s) to 7.80 m (As). We also found significant differences in head width (HW, proxy for body condition), with B2s being significantly leaner. Although this variation may reflect natural shape differences, we also estimated divergent regression lines of HW~TL indicating that this difference was greater at larger body sizes, with some anomalously thin adult female B2s. We suggest that these dissimilarities may indicate a density-dependent response, with leaner body condition in adults with higher energetic requirements, as the abundance of B2s is almost an order of magnitude greater than that of B1s and As. We hypothesize that food limitation resulted from a decline in carrying capacity during recent reductions in sea ice and warmer ocean temperatures.

Gymnosperm species richness patterns along the elevational gradient and its comparison with other plant taxonomic groups in the Himalayas

Phylogenetic constraints on ecophysiological adaptations and specific resource requirements are likely to explain why some taxonomic/functional groups exhibit different richness patterns along climatic gradients. We used interpolated species elevational distribution data and climatic data to describe gymnosperm species richness variation along elevational and climatic gradients in the Himalayas. We compared the climatic and elevational distributions of gymnosperms to those previously found for bryophytes, ferns, and angiosperm tree lineages to understand the respective drivers of species richness. We divided our study location into three regions: Eastern; Central; and Western Himalayas, in each calculating gymnosperm species richness per 100-m band elevational interval by determining the sum of species with overlapping elevational distributions. Using linear regression, we analyzed the relationship between species’ elevational mid-point and species’ elevational range size to test the Rapoport’s rule for gymnosperms in the Himalayas. Generalized linear models were used to test if potential evapotranspiration, growing degree days, and the number of rainy days could predict the observed patterns of gymnosperm species richness. We used the non-linear least squares method to examine if species richness optima differed among the four taxa. We found supporting evidence for the elevational Rapoport’s rule in the distribution of gymnosperms, and we found a unimodal pattern in gymnosperm species richness with elevation, with the highest species richness observed at ca. 3000 m. We also found a unimodal pattern of gymnosperm species richness along both the potential evapotranspiration and growing degree day gradients, while the relationship between species richness and the number of rainy days per year was non-significant. Gymnosperm species richness peaked at higher elevations than for any other plant functional group. Our results are consistent with the view that differences in response of contrasting plant taxonomic groups with elevation can be explained by differences in energy requirements and competitive interactions.

Exploration profiles drive activity patterns and temporal niche specialization in a wild rodent

Abstract Individual niche specialization can have important consequences for competition, fitness, and, ultimately, population dynamics and ecological speciation. The temporal window and the level of daily activity are niche components that may vary with sex, breeding season, food supply, population density, and predator’s circadian rhythm. More recently, ecologists emphasized that traits such as dispersal and space use could depend on personality differences. Boldness and exploration have been shown to correlate with variation in foraging patterns, habitat use, and home range. Here, we assessed the link between exploration, measured from repeated novel environment tests, activity patterns, and temporal niche specialization in wild eastern chipmunks (Tamias striatus). Intrinsic differences in exploration should drive daily activity patterns through differences in energy requirements, space use, or the speed to access resources. We used collar-mounted accelerometers to assess whether individual exploration profiles predicted: 1) daily overall dynamic body acceleration, reflecting overall activity levels; 2) mean activity duration and the rate of activity sequences, reflecting the structure of daily activity; and 3) patterns of dawn and dusk activity, reflecting temporal niche differentiation. Exploration and overall activity levels were weakly related. However, both dawn activity and rate of activity sequences increased with the speed of exploration. Overall, activity patterns varied according to temporal variability in food conditions. This study emphasizes the role of intrinsic behavioral differences in activity patterns in a wild animal population. Future studies will help us understand how yearly seasonality in reproduction, food abundance, and population density modulate personality-dependent foraging patterns and temporal niche specialization.

Energy metabolism and partition of lactating Zebu and crossbred Zebu cows in different planes of nutrition.

The aim of this study was to determine the energy metabolism and partition of lactating Gyr and F1 Holstein x Gyr (F1 HxG) cows in different planes of nutrition. Six F1 HxG and six Gyr cows with 130 days in milking (DIM) fed corn silage and concentrate were evaluated. The experiment consisted of four periods with different levels of feeding: 1st ad libitum dry matter intake (DMI) and the others with 5, 10 and 20% restricted DMI, related to the first one. An apparent digestibility assay was performed before measurements in the respiration chamber. Total feces were collected for three days. The cows were confined for 24h in the chamber in each period to determine methane and heat production (HP). F1 HxG had higher gross energy intake (GEI), metabolisable energy intake (MEI) and digestible energy intake (DEI). GE lost in feces was higher in F1 HxG (23.7% GEI) than in Gyr (20.5%) cows. Energy lost as methane and urine was similar between the groups. The metabolisability (q) was 0.67, and the efficiency of converting ME to NE (k) was 0.56. There was no difference in the energy requirements for maintenance between breeds (426.6 MJ/kg BW0,75 average value). The energy requirements for lactation were higher in F1 HxG animals due to the higher volume of milk produced, since there was no difference in energy requirements for production of one kg of milk.

Transformer incipient fault diagnosis on the basis of energy-weighted DGA using an artificial neural network

In this paper, a transformer incipient fault diagnosis model has been developed with the help of an artificial neural network (ANN), taking into account the difference in the energy required to produce the different fault gases. The key fault gases are indicative of the fault type prevailing in the transformer. However, in conventional studies, the energy difference in fault gas formation is not considered while adopting the key gas method for fault diagnosis. In this work, a weighting factor has been used to take into account this relative difference in energy requirement for various fault gas formations. The fault gas concentrations have been suitably weighted by their respective weighting factors before being used in the incipient fault diagnosis process. A backpropagation ANN has been appropriately trained using the weighted fault gas concentration for transformer incipient fault identification. The model has been trained to identify fault types as enlisted in the transformer fault-interpreting standard IEC-599. The developed ANN model has been tested for its diagnostic capability using a reported fault database. The comparative diagnosis results presented here show clear improvement in the diagnosis of transformer internal faults using the energy-weighted ANN model over the unweighted ANN model.

Female dominance in two basal primates, Microcebus murinus and Microcebus lehilahytsara: variation and determinants

Female social dominance over males can only be found in a small number of mammalian species, but is unusually concentrated among Malagasy lemurs. Three major hypotheses are currently discussed to explain this phenomenon, namely the energy conservation hypothesis, sleeping site hypothesis and ancestral lemur condition hypothesis. Since proximate determinants of female dominance have rarely been studied, this study aimed to investigate the influence of factors connected to these hypotheses, focusing on sex-specific differences in energy requirements and group composition in two closely related nocturnal lemur species. More specifically, the effects of species, season and age on agonistic behaviour and the expression of female dominance were tested, while the effects of individuality, body mass, breeding experience and habituation were controlled. Seasonal variations in intersexual dominance relationships were investigated in captivity in grey mouse lemurs, Microcebus murinus , a prominent female-dominant species, and Goodman's mouse lemurs, Microcebus lehilahytsara , whose agonistic behaviour was studied for the first time. Data were collected during a series of encounter experiments between one male and one female (15 dyads of M. murinus and nine of M. lehilahytsara ) during the reproductive and nonreproductive seasons. Moderate female dominance was expressed in both species with females winning the majority of conflicts year round, independently of context. However, effects of season and species were found in conflict rates, in the probability for females to win conflicts, and in the number of dominant females. Moreover, the age difference between dyad partners and the breeding experience of females influenced whether conflicts were decided in favour of males or females. It can be concluded that female dominance probably represents an ancestral trait in mouse lemurs and it is proposed that its evolution might have been driven by sex-specific energetic constraints prevailing in the species-specific ancestral habitats, and may moreover be influenced by the species-specific social organization.

Age and Weight Loss After Bariatric Surgery: Cause or Consequence?

In spite of its indisputable role in the treatment of obesity,bariatric surgery is not absent of cutbacks and complica-tions. Cumulative experience is allowing the discovery offactors associated with weight loss after bariatric surgery[1], which may allow the development of more selectiveand effective interventions. In this regard, both Contreraset al. [2] and Scozzari et al. [3] reports bring an importantcontribution, by clearly showing that patients’ age nega-tively associates with success in weight loss. In the dis-cussion of their results, the authors consider a range offacts possibly interfering with weight loss in people ofmore advanced age: from differences in energy require-ments to social and psychological aspects and, probably ofgreat importance, an impaired metabolic capacity and alower lipolytic activity.Results obtained by our group [4], in a sample of 163obese patients, showed that, in good agreement with theresults of Scozzari et al., younger patients (<50 years)achieved a greater weight loss after 12 months of follow-up (80 % excess weight loss (EWL) vs 70 % EWL; p=0.01). More interestingly, in the preoperative period and incomparison with older patients, younger (and most respon-sive) patients had significantly lower fasting glucose levels(93 vs 111 mg/dL; p<0.001) [4] and were less contaminat-ed with persistent organic pollutants (POPs) in visceraladipose tissue (168.9±13.7 ng/g of fat vs 311.0±32.7 ng/goffat,p<0.0001) [POPs data to be published]. Specifi-cally in our analysis, the effect of age disappeared afteradjustment for fasting blood glucose levels.As both higher fasting glucose [ 5] levels and higher levels ofPOPs [6] in adipose tissue will decr ease lipolysis, this seems tobe a most important mechanism behind the difficulty of olderpeople to respond to weight-los ing interventions. It would beinteresting to study the influence of age on weight loss by otherinterventions and to further evaluate the capacity of fastingglucose and POPs levels to predict weight loss independentlyof age.

Relative Importance of Social Status and Physiological Need in Determining Leadership in a Social Forager

Group decisions on the timing of mutually exclusive activities pose a dilemma: monopolized decision-making by a single leader compromises the optimal timing of activities by the others, while independent decision-making by all group members undermines group coherence. Theory suggests that initiation of foraging should be determined by physiological demand in social foragers, thereby resolving the dilemma of group coordination. However, empirical support is scant, perhaps because intrinsic qualities predisposing individuals to leadership (social status, experience or personality), or their interactions with satiation level, have seldom been simultaneously considered. Here, we examine which females initiated foraging in eider (Somateria mollissima) brood-rearing coalitions, characterized by female dominance hierarchies and potentially large individual differences in energy requirements due to strenuous breeding effort. Several physiological and social factors, except for female breeding experience and boldness towards predators, explained foraging initiation. Initiators spent a larger proportion of time submerged during foraging bouts, had poorer body condition and smaller structural size, but they were also aggressive and occupied central positions. Initiation probability also declined with female group size as expected given random assignment of initiators. However, the relative importance of physiological predictors of leadership propensity (active foraging time, body condition, structural size) exceeded those of social predictors (aggressiveness, spatial position) by an order of magnitude. These results confirm recent theoretical work suggesting that ‘leading according to need’ is an evolutionary viable strategy regardless of group heterogeneity or underlying dominance structure.

Feedlot performance, feed efficiency reranking, carcass traits, body composition, energy requirements, meat quality and calpain system activity in Nellore steers with low and high residual feed intake

The aim was to evaluate growth, carcass traits, feed efficiency reranking, body composition, calpain system activity and meat quality in Nellore steers that were phenotypically ranked for high and low residual feed intake (RFI). Seventy-two Nellore steers (16–21 month-old, 334±19kg BW) had free access to a feedlot diet for 70d (feeding period 1, P1). Daily dry matter intake (DMI), body weight gain (ADG) and ultrasound carcass traits were measured individually. The 12 lowest and the 12 highest RFI steers were classed as low- and high-RFI groups and were fed for a second feeding period (feeding period 2, P2). Spearman's rank correlation was performed for RFI and gain-to-feed ratio (G:F) measured over P1 and P2. The carcass traits, meat quality and calpain system activity were evaluated at slaughter, and body composition was determined. In P1, low-RFI steers had greater G:F (0.159 vs. 0.134; P<0.001), lower DMI (9.30 vs. 11.1kg/d; P<0.0001), lower RFI (−0.80 vs. 0.85kg/d; P<0.0001), and tended to have lower rates of rump fat gain (4.48 vs. 6.05mm; P=0.06), but no differences were observed for ADG, BW, and other traits measured by ultrasound (P>0.05). In P2, no differences between RFI classes were observed for G:F and DMI as a percentage of BW (P>0.05), and small differences were observed for DMI (8.25 vs. 8.99kg/d, P<0.05) and RFI (−0.28 vs. +0.29kg/d, P=0.06). The ranking correlations for RFI and G:F measured consecutively in P1 and P2 were low to moderate (r=0.11–0.40). Low-RFI steers had lower requirements of metabolizable energy (ME) for maintenance (131 vs. 160Mcal/kg EBW0.75d−1, P<0.05), but no differences were observed for fat and protein gain, retained energy and efficiency of ME use for gain (P>0.05). No differences between low- and high-RFI steers were observed for carcass traits at slaughter; however, low-RFI steers had 8.1kg less gastrointestinal fat than high-RFI steers. There were no RFI effects on meat shear force and the activities of μ-calpain, m-calpain and calpastatin (P>0.05). High-RFI steers had greater MFI in 1d aged LM (53.9 vs. 40.8, P<0.05). The variation in feed efficiency between high- and low-RFI Nellore steers is related to differences in energy requirements and deposition of fat on internal organs. The ranking for feed efficiency is altered as cattle become older. The selection for improved RFI in Nellore cattle may reduce feed requirements for beef production without affecting meat tenderness and enzymatic activity of the calpain system.

Associations between fat, sugar and other macronutrient intakes in the National Diet and Nutrition Survey

SummaryObservational studies show an inverse relationship between fat and sugar within diets, described as the ‘fat‐sugar seesaw’. It has been suggested however, that this is a consequence of expressing macronutrient intakes as percentages of energy intake rather than by the dietary choices made by individuals. To test this we examined the associations between macronutrient intakes in the diets of adults (n = 1724) participating in the UK National Diet and Nutrition Survey (NDNS) and within the same adults across different days of the week. Pearson's correlations were calculated between the macronutrient intakes from fat, total sugar, intrinsic sugars, non‐milk extrinsic sugars (NMES), non‐sugar carbohydrate, protein and alcohol. Energy intakes relative to estimated basal metabolic rate (BMR) were calculated to partially account for differences in energy requirements. Pearson's correlations also examined associations between the same macronutrients in foods from the Nutrient Databank (ND), used to analyse dietary intakes in the NDNS. Correlations between fat and sugar(s) were calculated in five ways: (i) percentage energy between individuals; (ii) amount (g) between individuals; (iii) amount (g) relative to BMR between individuals; (iv) within individuals over seven days; and (v) between food items in the ND. Negative correlations were obtained between mean daily percentage energy intakes of fat and, total sugars, NMES and intrinsic sugars (all P &lt; 0.001). However, when mean daily macronutrient intakes were expressed in weight (g)/day, these were all positively correlated (all P &lt; 0.001). Mean estimated correlations between macronutrient intakes (g/day) for each individual across the days of the week were also positive, indicating a lack of fat‐sugar seesaw effect. Within the ND, the correlation between fat and total sugar (g/100g of food) was weakly positive (P = 0.006). Only when examining the correlation between fat and sugar(s) between individuals in percentage terms (% energy) was the fat‐sugar seesaw evident; in all other methods the correlations between fat and sugar(s) were positive. Examination of the effects of using percentage energy values to describe the macronutrient composition demonstrated that the fat‐sugar seesaw is only an inevitable mathematical consequence, rather than the result of dietary choice. Comparing diet composition in percentage terms alone can therefore be misleading. It is only when examined as absolute values (weight), as well as percentage contributions to energy, that the interrelationships between macronutrients can be studied fully.

La pneumonie tuberculeuse à propos de dix cas

SecE is an essential membrane component of theEscherichia coliprotein translocation machinery, which utilizes ATP and the proton motive force as energy sources. ThesecEhomologue of marineVibrio alginolyticus,in which protein translocation requires ATP and the sodium motive force, was cloned, sequenced, and characterized. Unlike most SecE homologues found in various organisms, SecE ofV. alginolyticus(Va-SecE) possesses three transmembrane sequences likeE. coliSecE (Ec-SecE) and complements the ΔsecEmutation ofE. coli.Alignment of the Ec-SecE and Va-SecE sequences revealed that the non-essential N-terminal half was less homologous than the essential C-terminal half between the two SecEs. TheE. colistrain was able to grow and translocate the secretory protein in the complete absence of Ec-SecE when Va-SecE was expressed. The stabilization of SecY overproduction by Va-SecE was as effective as that by Ec-SecE, indicating that Va-SecE interacts withE. coliSecY despite the difference in energy requirement.

Energy requirements of puppies of two different breeds for ideal growth from weaning to 28 weeks of age

To ensure an optimal growth is crucial in raising healthy dogs, especially in large and giant breeds. Dogs with a moderate growth velocity tend to have lesser problems with developmental orthopaedic diseases than those with forced or maximum weight gain. In this study, the energy needs of growing dogs from two different breeds (Beagles as a medium-size breed and Foxhound crossbreds as a large-size breed) to ensure a growth development as recommended by the National Research Council (NRC) were determined at the age of 6-28 weeks. After weaning at the age of 6 weeks, the food rations sufficient to meet the energy requirements of each individual puppy were adjusted every other day according to growth level, guaranteeing a development consistent with the recommended weight curve for the respective breed size. The food and therefore energy intake of the puppies was registered daily; it ranged from 0.72 to 2.34 times the maintenance requirements with little effect of age. During the whole period, however, there was a consistent breed difference: Foxhound-Boxer-Ingelheim Labrador crossbreds (FBIs) had higher energy intakes expressed as multiples of maintenance than Beagles, suggesting that during the major period of growth, the energy requirement is not a function of age. Adult Beagles and FBIs showed similar differences in energy requirements as already during growth as shown in this study. This indicates that breed differences in energy requirements have already to be taken into account during growth. On the other hand, the results showed clearly lower energy needs for growth in these two different breeds than recommended in the NRC.

Energy intake for maintenance in a mammal with a low basal metabolism, the giant anteater (Myrmecophaga tridactyla)

Giant anteaters (Myrmecophaga tridactyla) are among those mammals for which a particularly low metabolism has been reported. In order to verify presumably low requirements for energy, we used eight anteaters (two males, six females; aged 1-14 years; body mass between 46 and 64 kg) in a total of 64 individual trials, in which a variety of intake levels was achieved on various diets. Digestible energy (DE) intake was quantified by measuring food intake and faecal excretion and analysing representative samples for gross energy, and animals were weighed regularly. Maintenance DE requirements were calculated by regression analysis for the DE intake that corresponded to zero weight change. Differences between individuals were significant. Older anteaters (n = 3 animals aged 12-15 years in 29 trials) had lower relative requirements than younger ones (n = 5 animals aged 1-7 years in 35 trials); thus, giant anteaters resemble other mammals in which similar age-specific differences in energy requirements are known. However, estimated maintenance requirements were 347 kJ DE/kg(0.75)/day in the anteaters, which is low compared to the 460-580 kJ DE/kg(0.75)/day maintenance requirements of domestic dogs. The lack of knowledge that metabolic requirements are below the mammalian average could make species particularly susceptible to overfeeding, if amounts considered adequate for average mammals were provided. Non-scientific reports on comparatively fast growth rates and high body masses in captive giant anteaters as compared to free-ranging animals suggest that body mass development and feeding regimes in captivity should be further assessed.

Seasonal differences in energy requirements of Garden Warblers Sylvia borin migrating across the Sahara desert

The Sahara desert acts as an ecological barrier for billions of passerine birds on their way to and from their African wintering areas. The Garden Warbler Sylvia borin is one of the most common migrants involved. We used body mass of this species from Greece in autumn and spring to simulate the desert crossing and to assess how body mass relates to fuel requirement. The flight range estimates were adjusted to the seasonal extent of the desert, 2200 km in autumn and about 2800 km in spring. In autumn, with an average fuel load of about 100% of body mass without fuel, birds were not able to cross the desert in still air, but northerly winds prevail during September and with the average wind assistance only one in 14 was predicted to fail to make the crossing. Body mass data from spring, after the desert crossing, was used to estimate departure body mass from south of the desert. The average wind assistance in spring is close to zero and departure body mass of the average bird arriving at Antikythira, a small Greek island, under such conditions was estimated to be 34.6 g, which corresponded to a fuel load of 116%. Calculations based on 1% body mass loss per hour of flight showed slightly larger body mass loss than that calculated from flight range estimates. The results suggest that passerine birds about to cross the eastern part of the Sahara desert need to attain a larger fuel load in spring than in autumn.

Measurement of marine productivity using 15N and 13C tracers: Some methodological aspects

Various experiments involving the measurement of new, regenerated and total productivity using 15N and 13C tracers were carried out in the Bay of Bengal (BOB) and in the Arabian Sea. Results from 15N tracer experiments indicate that nitrate uptake can be underestimated by experiments with incubation time <4 hours. Indirect evidence suggests pico- and nano-phytoplankton, on their dominance over microphytoplankton, can also influence the f-ratios. Difference in energy requirement for assimilation of different nitrogen compounds decides the preferred nitrogen source during the early hours of incubation. Variation in light intensity during incubation also plays a significant role in the assimilation of nitrogen. Results from time course experiments with both 15N and 13C tracers suggest that photoinhibition appears significant in BOB and the Arabian Sea during noon. A significant correlation has been found in the productivity values obtained using 15N and 13C tracers.

The influence of selected factors on energy requirements for plain milling of beech wood

The paper deals with differences in energy requirements for cutting input at plain milling of beech wood with and without false heart with different changing parameters of cutting and feed speed and angular geometry of the tool. Created on optimal model from the aspect of not only energy consumption but also the quality of milling, which would also decisively affect the economic indicators of the wood &amp;ndash; working process. &amp;nbsp;