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The interaction between the ruminal microflora and the host is examined by correlating bacterial diversity with fermentation measurements and feed efficiency traits, including dry matter intake, feed conversion ratio, average daily gain and residual feed intake, by using culture-independent methods. The results have shown that particular bacteria and their metabolism in the rumen has contributed to differences in host feed efficiency under a low-energy diet and have also correlated PCR-denaturing gradient gel electrophoresis (DGGE) bands representing specific bacteria to metabolites in the bovine rumen and to host feed efficiency traits.

Suppression hybridization is used for identifying the genes present in Fibrobacter succinogenes S85 but absent from Fibrobacter intestinalis DR7. Two gene clusters encoding NADH-ubiquinone oxidoreductase subunits shared by Fibrobacter genera have played a vital role in energy metabolism.

Byline: Y. Demirel Every developed and adapted biological system extracts useful energy from outside, converts, stores it, and uses for muscular contraction, substrate transport, protein synthesis, and other energy utilising processes. This energy management in a living cell is called the bioenergetics, and the useful energy is the exergy, which is destroyed in every irreversible process because of the entropy production. The converted exergy is the adenosine triphosphate (ATP) produced through the oxidative phosphorylation coupled to respiration in which the exergy originates from oxidation of reducing equivalents of nutrients. A living cell uses the ATP for all the energy demanding activities; it has to maintain non-vanishing thermodynamic forces, such as electrochemical potential gradient, and hence is an open, nonequilibrium system, which manages the exergy destruction and power production to adapt the fluctuations in energy demand and production within mitochondria. A simplified example presented here shows that the use of exergy analysis is helpful for understanding and analysing oxidative phosphorylation in bioenergetics.

The objective of this study was to determine the effect of varying concentrations of dietary fat and carbohydrate on changes in body composition of Holstein bull calves fed under isocaloric and isonitrogenous intake conditions. Thirty-two calves were assigned to a randomized block design with three dietary treatments, eight calves per treatment, and one baseline group of eight calves. Animals were reared from birth to 85 kg live BW (SEM = 0.57). All calves began treatments between 2 and 6 d of age. Three different milk replacer treatment diets were designed to deliver 14.8 (low fat, LF), 21.6 (medium fat, MF), or 30.6% of DM (high fat, HF) fat; 55.3, 46.7, or 35.4% of DM lactose; and 23.5, 24.8, or 27.0% of DM CP, respectively. Gross energy values were 4.62, 5.09, and 5.77 Mcal/kg for the LF, MF, and HF milk replacers, respectively. From d 1 to 14, calves were offered 0.24 Mcal intake energy/kg B[W.sup.0.75], adjusted weekly based on increases in BW, and 0.28 Mcal intake energy/kg B[W.sup.0.75] from d 15 to slaughter. Dry feed was not offered. Dry matter, energy, CP, and fat intakes were 55.2 kg, 257.6 Mcal, 13.0 kg, and 8.2 kg; 52.8 kg, 268.8 Mcal, 13.1 kg, and 11.4 kg; and 46.8 kg, 270.3 Mcal, 12.6 kg, and 14.3 kg for the LF, MF and HF treatments, respectively. Energy and CP intakes did not differ among treatments (P = 0.63 and 0.79, respectively). Fat and DMI were different among treatments (P = 0.001 and 0.02, respectively). Empty BW gains were 0.61, 0.61, and 0.65 kg/d for LF, MF, and HF, respectively, and were not different among treatments (P = 0.27). Empty body CP, water, and ash gain were not different among treatments (P = 0.65, 0.99, and 0.57, respectively). Empty body retained energy and fat gain were 27.2 and 57.7% greater for calves fed the HF than for those fed the LF diet (P = 0.06 and 0.006, respectively). Fat as a percentage of the whole empty body on a water-free basis was lower for calves consuming the LF diet (28.6%) than for those fed the HF diet (34.6%), whereas percentage of CP on an empty body, water-free basis was greater for calves consuming the LF diet (59.2%) than for those fed the HF diet (54.9%) (P = 0.006). The results of this study demonstrated that, under isocaloric and isonitrogenous intake conditions, equivalent dietary energy from fat compared to carbohydrate, above 15% fat, has no beneficial purpose unless additional fat deposition is required in the animal. Further, the data demonstrate significant changes in body composition independent of growth rate. Key Words: Body Composition, Calves, Energy, Fat, Growth, Protein

Compromising alterations in gastrointestinal architecture are common during the weaning transition of pigs. The relation between villous atrophy and epithelial barrier function at weaning is not well understood. This study evaluated in vitro transepithelial transport by Ussing metabolic chambers, local alterations in T-cell subsets and villous architecture at low energy intake level and their relation with lactose/protein ratios in the diet. Pigs (n = 66, 26 d old) were sampled either at weaning (d 0), d 1,2 or 4 postweaning. Piglets received one of three diets at a low energy intake level, which differed in lactose and protein ratio as follows: low lactose/high protein (LL/HP), control (C), or high lactose/low protein (HL/LP). Mean digestible energy intake was 648 kJ/pig on d 1, 1668 kJ/pig on d 2, 1995 kJ/pig on d 3 and 1990 kJ/pig on d 4 postweaning. The [CD4.sup.+]/[CD8.sup.+] T-lymphocytes ratio decreased after weaning (P [is less than] 0.05). Decreased paracellular transport (P [is less than] 0.01), greater villous height (P [is less than] 0.01), shallower crypts and lower villus/crypt ratios (P [is less than] 0.01) were observed on d 2 compared with d 0. Piglets consuming the HL/LP diet tended to have less paracellular transport (P [is less than] 0.10) and greater villous height (P [is less than] 0.10) compared with piglets fed the other diets. During the first 4 d postweaning, the effect of diet composition on mucosal integrity was not as important as the sequential effects of low energy intake at weaning. Stress and diminished enteral stimulation seem to compromise mucosal integrity as indicated by increased paracellular transport and altered T-cell subsets. J. Nutr. 131: 1520-1527, 2001. KEY WORDS: * piglets * weaning * energy intake * epithelial barrier function * T lymphocytes

Is there any ecological purpose in assuming that perception for action exists only through a global array of energy? Unlike Stoffregen & Bardy, who assume that behavior consists of movements, we would argue that behavior consists of a stable coupling between perception and action achieved through experience in an adaptive context. Determining target position in an aiming manual task and temporal control of impact movement illustrate that patterns of energy used for action are task-dependent.

Systematic problems exist in the quantification of food intake in populations using traditional self-reported measures. The objective of this study was to determine the effectiveness of an innovative multimedia diet record (MMDR) for dietary energy intake assessment, Dietary intake was estimated by combining the use of a microcassette tape recorder and 35-mm camera in 53 women whose ages ranged from 50 to 93 y (64.9 [+ or -] 11.3 y), with body weights of 62.4 [+ or -] 12.2 kg and body mass indexes (BMI) of 24.4 [+ or -] 4.0 kg/[m.sup.2], Using household measures, subjects voice-recorded and photographed all food and beverages consumed for four consecutive days. A two-point doubly-labeled water (DLW) method was used over 13 d to calculate carbon dioxide production, total body water, and subsequently, total energy expenditure (TEE) through the use of a food quotient. Mean body weight did not change between d 1 and 14. TEE and reported energy intake were compared using MMDR. Mean reported energy intakes 7.5 [+ or -] 1.9 MJ/d (1774 [+ or -] 476 kcal/d) were lower (P [is less than] 0.01) than TEE by 10.4 [+ or -] 3.1 MJ/d (2477 [+ or -] 736 kcal/d), indicating underreporting of food intake. Reporting accuracy (reported energy intake/TEE' 100%) was 76.0 [+ or -] 22.9%. Mean energy expenditure (MJ/d), as determined by doubly-labeled water, was higher (P [is less than] 0.01) in each stratified age range when compared to reported energy intake by MMDR. There were no significant differences in reporting accuracy among the stratified age groups. Using the MMDR method, this population of weight-stable women underreported their food intakes compared to their determined energy expenditure estimated by DLW. J. Nutr. 130: 802-805, 2000. KEY WORDS: * total energy expenditure * energy intake * doubly-labeled water * dietary assessment * humans

Six subjects walked on a programmable treadmill (Woodway mod. ERGO-LG2, Germany) both at constant (3.5 [+ or -] 0.0 km/h) and oscillating speed ([+ or -] 0.5, [+ or -] 1.0, +1.5, [+ or -] 2.0 km/h), set to change between the two limits in 3 seconds. In each condition oxygen consumption and 3D motion analysis were performed on 18 body joints at a frequency of 100 Hz. The same experimental protocols were reproduced on the walkway by allowing subject to adapt their stride frequency to an audio signal corresponding to the sinusoidal stride frequency changes, individually measured on the treadmill. Differently from what expected, only E [+ or -] 2.0 resulted to be different from E [+ or -] 0.0, both for the treadmill and the walkway conditions. The analysis of the time course of the mechanical external work, the one needed to accelerate and lift the body centre of mass, reveals that a strategy devoted to benefit from the normal mechanical energy fluctuations, as occurring at `constant speed', is likely to be used to cope with different time-sequences of acceleration/deceleration, within a given speed oscillation range.

Small hummingbirds in hovering flight achieve the highest known mass-specific metabolic rates among vertebrates. Their foraging activity provides the opportunity for studies that address a wide range of issues. What factors determine resting and active metabolic rates and what are their physiological and biochemical bases? How is behaviour integrated with physiology and biochemistry to facilitate net energy gain? We shall explore these issues in the context of their migratory flight from British Columbia to Mexico. In their southward migration, rufous hummingbirds stop to refuel by feeding on floral nectar in subalpine meadows. In such habitats, they face the task of achieving net energy gain despite the high energetic costs of flight and thermoregulation. On a cold morning in a subalpine meadow, rufous hummingbirds achieve the highest time-averaged metabolic rates (250 W/kg) known among vertebrates. Funded by NSF 9507407 and NSERC Operating Grant.

Many birds use an intermittent flap-bounding or flap-gliding (undulating) flight strategy in preference to flying continuously. Because of the aerodynamic demands and constraints of flight these mechanisms are significant for birds, although suprisingly are relatively rare in bats. Bounding flight is confined to small birds, while undulating flight is more common in larger species. For some birds intermittent strategies (particularly bounding) are obligate, while for others they are facultative responses to flight path geometry or environmental conditions. Intermittent flapping may be a means of balancing or `gearing' the energy required for flight against the energy available from the flight muscles, or may be to reduce the mechanical or aerodynamic power required to fly. Novel theoretical models of power consumption are combined with observations of varying flight patterns with speed and with new measurements of body aerodynamics in European Starling Sturnus vulgaris to explore alternative hypotheses.

The article discusses and reviews the physiology of weight gain as well as loss and how many calories it is necessary to reduce in order to achieve weight loss and avoid becoming overweight. Obesity is very difficult to reverse; however, small changes in lifestyle can go a long way in obesity prevention.

Oxygen is vital for the conversion of food into energy and for basic metabolic processes such as tissue respiration. The daily oxygen consumption of an average individual is equal to the amount of daily food intake. Quantitative analysis of oxygen consumption indicated that a moderately active individual needs 1.5 pounds of oxygen to metabolize 1.4 pounds of food which generate 3,000 kilocalories of energy.

Halophilic microorganisms spend large amounts of energy to maintain steep gradients of K+ and NA+ concentrations across their cytoplasmic membrane. The energetic cost of salt adaptation can probably determine what kind of metabolism can support life at the highest salt concentration. The halophilic homoacetogenic bacteria uses KCl as an intracellular solute to exist while producing acetate from H2 + CO2.

An extension of the symmetry-adapted basis defect patterns (BDPs), which is used to analyze the impact of static diagonal and off-diagonal energy disorder on the excitonic structure and spectroscopic features of cyclic arrays of coupled chromophores, was introduced. This follow-up work demonstrated that the BDP approach is most applicable to weak disorder. Findings revealed that interpretation of electric field effects on the B850 and B875 absorption bands must incorporate the influences of energy disorder.