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Energy Content (energy + content)

Distribution by Scientific Domains
Life Sciences52%
Earth and Environmental Science18%
Medical Sciences12%
Chemistry10%
3 Other Domains8%

Kinds of Energy Content

  • gross energy content
    		•

    Selected Abstracts

    Effects of dietary l -carnitine supplements on growth and body composition in beluga sturgeon (Huso huso) juveniles

    JOURNAL OF APPLIED ICHTHYOLOGY, Issue 6 2008
    M. Mohseni
    Summary The effects of dietary l -carnitine on growth performance, whole body composition and feed utilization were studied in beluga, Huso huso. Fish were randomly allocated in 15 tanks (30 fish per tank) and triplicate groups were fed to satiety during 84 days one of five isonitrogenous (41% CP) and isoenergetic (20 MJ kg,1) diets, each differing in l -carnitine content [0 (control), 300, 600, 900 and 1200 mg kg,1 diet]. At the end of the trial, fish grew from 19- to 23-fold in weight, from 8.4 g to a maximum of 191 g. Fish fed 300,600 mg l -carnitine had the highest specific growth rate (SGR, 3.69 and 3.72% day,1) and protein efficiency ratio (PER, 0.95 and 0.99), and the lowest feed conversion ratio (FCR, 1.4 and 1.3) than the other groups (P < 0.0001). SGR, PER and FCR were the poorest for fish fed 1200 mg l -carnitine, while fish fed the unsupplemented and 900 mg l -carnitine supplemented diet showed intermediate performance. Body lipid concentration decreased significantly from 5.8 to 5.1% (P < 0.0001) with dietary l -carnitine supplementation increasing from 0 to 300 mg. Energy content was significantly lower in fish fed the 900 and 1200 mg l -carnitine diet (5.8 MJ kg,1), when compared with the other treatment groups (6.4,6.6 MJ kg,1). The results indicated that feeding sturgeon on diets supplemented with 300 mg l -carnitine kg,1 diet improved growth performance, and stimulated protein-sparing effects from lipids. [source]

    Response of SDOF system to non-stationary earthquake excitation

    EARTHQUAKE ENGINEERING AND STRUCTURAL DYNAMICS, Issue 15 2004
    R. S. Jangid
    Abstract Earthquake excitation is often modelled by non-stationary random process (i.e. uniformly modulated broad-band excitation) for analysis of structural safety subjected to seismic hazards. In this paper, the non-stationary response of a single-degree-of-freedom (SDOF) system to non-stationary earthquake motion is investigated for different shapes of modulating functions. The evolutionary power-spectral density function (PSDF) of the displacement of the SDOF system is obtained using the time-varying frequency response function and the PSDF of the earthquake excitation. The close form expressions for time-varying frequency response function are derived for different shapes of the modulating functions. In order to study the effects of the shape of the modulating function, a comparison of the non-stationary earthquake response of the SDOF system is also made for different modulating functions having the same energy content. Copyright © 2004 John Wiley & Sons, Ltd. [source]

    Prey protein influences growth and decoration building in the orb web spider Argiope keyserlingi

    ECOLOGICAL ENTOMOLOGY, Issue 5 2009
    SEAN J. BLAMIRES
    Abstract. 1. Protein is important for a foraging animal to consume, as it promotes growth and enhances survival, particularly in web-building spiders, which need to invest considerable protein into web building and may trade-off growth for web investment. 2. The influence of dietary protein uptake on growth and web investment was tested in the orb web spider Argiope keyserlingi, by feeding them flies reared on three different media: (1) high protein, (2) low protein, and (3) standard (control) media. There was a negative correlation between protein and energy content of the flies across treatments; flies reared on the high protein media had the highest protein, but lowest energy, while flies reared on the low protein media had the lowest protein but highest energy. 3. It was found that silk investment and web architecture in A. keyserlingi was not affected by diet. Growth and decoration building were both enhanced when spiders were fed a high protein diet. 4. It was concluded that protein intake, rather than energy, influenced both growth and decoration building because: (1) protein intake enhances growth in other animals, (2) protein is essential for silk synthesis, especially aciniform silk, and (3) protein is a limiting factor actively sought by foraging animals in natural environments. [source]

    Bacterial traits, organism mass, and numerical abundance in the detrital soil food web of Dutch agricultural grasslands

    ECOLOGY LETTERS, Issue 1 2005
    Christian Mulder
    Abstract This paper compares responses to environmental stress of the ecophysiological traits of organisms in the detrital soil food webs of grasslands in the Netherlands, using the relationship between average body mass M and numerical abundance N. The microbial biomass and biodiversity of belowground fauna were measured in 110 grasslands on sand, 85 of them farmed under organic, conventional and intensive management. Bacterial cell volume and abundance and electrophoretic DNA bands as well as bacterial activity in the form of either metabolic quotient (qCO2) or microbial quotient (Cmic/Corg) predicted the response of microorganisms to stress. For soil fauna, the logarithm of body mass log(M) was approximately linearly related to the logarithm of numerical abundance log(N) with slope near ,1, and the regression slope and the proportion of predatory species were lower in intensive agroecosystems (more reduced substrates with higher energy content). Linear regression of log(N) on log(M) had slope not far from ,3/4. The approach to monitoring data illustrated in this paper could be useful in assessing land-use quality. [source]

    A new optimal foraging model predicts habitat use by drift-feeding stream minnows

    ECOLOGY OF FRESHWATER FISH, Issue 1 2002
    G. D. Grossman
    Abstract , There is substantial need for models that accurately predict habitat selection by fishes for purposes ranging from the elaboration of ecological theory to the preservation of biodiversity. We have developed a new and highly tractable optimal foraging model for drift-feeding fishes that is based on the profitability of occupying varying focal-point velocities in a stream. The basic model can be written as: Ix = (Ex * Px) = {(D * A * V) * [1/(1 + e(b + cV))]} , Sx, where: (1) Ix is the net energy intake at velocity x; (2) E is prey encounter rate; (3) P is prey capture success rate which can be modelled as 1/(1 + e(b + cV)) where b and c are fitting constants from the prey capture success curve; (4) D is the energy content of prey (J/m3) in the drift; (5) A is the visual reactive area of the fish; (6) V is velocity (cm/s); and (7) S is the cost of maintaining position (J/s). Given that D, A and S can be considered constant over the range of velocities occupied by these fishes, the model reduces to e(b + cV) = 1/(cV , 1) which we solved iteratively to yield an optimal focal-point velocity for species in each sample. We tested the model by comparing its predictions to the mean focal-point velocities (i.e. microhabitats) occupied by four species of drift-feeding minnows in two sites in a stream in North Carolina, USA. The model successfully predicted focal-point velocities occupied by these species (11 out of 14 cases) in three seasonal samples collected over 2 years at two sites. The unsuccessful predictions still were within 2 cm/s of the 95% confidence intervals of mean velocities occupied by fishes, whereas the overall mean deviation between optimal velocities and mean fish velocities was small (range = 0.9 and 3.3 cm/s for the warpaint shiner and the Tennessee shiner, respectively). Available focal-point velocities ranged from 0,76 to 0,128 cm/s depending on site and season. Our findings represent one of the more rigorous field tests of an optimal foraging/habitat selection model for aquatic organisms because they encompass multiple species and years, and for one species, multiple sites. Because of the ease of parameterization of our model, it should be readily testable in a range of lotic habitats. If validated in other systems, the model should provide critical habitat information that will aid in the management of riverine systems and improve the performance of a variety of currently used management models (e.g. instream flow incremental methodology (IFIM) and total maximum daily load calculations (TMDL)). Resumen 1. Existe una grave necesidad de modelos que predigan con precisión la selección de hábitat por parte de los peces con fines que van del desarrollo de la teoría ecológica a la conservación de la biodiversidad. Nosotros hemos desarrollado un modelo nuevo y de fácil manejo de alimentación óptima para peces que se alimentan de la deriva que se fundamenta en los diferentes beneficios energéticos derivados de ocupar velocidades focales distintas en un río. 2. El modelo básico puede formularse como: Ix = (Ex * Px) = {(D * A * V) * [1/(1 + e(b + cV))]} , Sx, donde: (1) Ix es el energía neta obtenida a la velocidad, x; (2) V es la velocidad (cm/s); (3) A es el area visual de reacción del pez; (4) D es la energía contenida en las presas (J/m3) en la deriva; (5) E es la tasa de encuentro de presas; (6) P es la probabilidad de captura de la presa, que puede representarse como 1/(1 + e(b + cV)) donde b y c son constantes; y (7) S es el coste de nadar para mantener la posición en la corriente (J/s). Puesto que D, A y S pueden considerarse constantes en el rango de velocidades que ocupan estos peces, el modelo se reduce a e(b + cV) = 1/(cV , 1) que resolvimos iterativamente para obtener una velocidad focal óptima para cada especie en cada muestreo. 3. Probamos el modelo comparando su predicciones con la velocidades focales medias (i.e. microhabitats) ocupadas por cuatro especies de ciprínidos que se alimentan de la deriva en un río de Carolina del Norte. El modelo predijo con éxito las velocidades focales ocupadas por estas especies (11/14 casos) en tres muestreos estacionales llevados a cabo a lo largo de dos años en dos estaciones. Incluso las predicciones fallidas se diferenciaron en menos de 2 cm/s del límite de confianza al 95% CIs de las velocidades medias ocupadas, y la diferencia media entre predicciones y observaciones fue pequeña (rango = 0.9 cm/s warpaint shiner, a 3.3-cm/s Tennessee shiner). El rango de las velocidades focales medias disponibles fue de 0,76 cm/s a 0,128 cm/s dependiendo de la localidad y estación del año. 4. Nuestros resultados son una de las pruebas de campo más rigurosas de un modelo de alimentación óptima/selección de hábitat para organismos acuáticos puesto que incluyen diversas especies, años y, para una de las especies, localidades. La facilidad de la estima de los parámetros del modelo hace que sea fácil probarlo en diversos hábitats lóticos. Si es validado en ellos, el modelo debería proporcionar información valiosa que ayudará a la gestión de los sistemas fluviales y mejorará los resultados obtenidos a través de varios modelos usados actualmente para la gestión (p.e. IFIM y cálculos TMDL). [source]

    The distributional effects of carbon and energy taxes: the cases of France, Spain, Italy, Germany and UK

    ENVIRONMENTAL POLICY AND GOVERNANCE, Issue 4 2002
    Dr. E. J. Symons
    This paper examines the likely immediate impact effect of some pollution taxes on the tax burden of households in a number of European countries. The total effect on households of such taxes is assessed using input,output analysis. Thus both the direct effect of taxes, through increased fuel prices, and the indirect effect, through increased prices of other goods, can be assessed simultaneously. This input,output approach allows the generation of direct plus indirect pollution intensities for all household consumption categories, for, in principle, a number of pollutants (CO2, SO2, NOx, particulates). These intensities could then be used to assess the impact on households of pollution taxes. This paper concentrates on CO2 and energy, performing a static analysis of the effect of a tax on the carbon or energy content of goods using the known consumption patterns for the various countries, both in aggregate and for different income groups. This allows a first assessment of the regressive/progressive effects of such taxes and an indication of consumer welfare loss. Copyright © 2002 John Wiley & Sons, Ltd and ERP Environment. [source]

    Veligers of an introduced bivalve, Limnoperna fortunei, are a new food resource that enhances growth of larval fish in the Paraná River (South America)

    FRESHWATER BIOLOGY, Issue 9 2010
    ESTEBAN M. PAOLUCCI
    Summary 1.,Larvae of ,sábalo', Prochilodus lineatus, whose adults represent over 60% of overall fish biomass in the Río de la Plata Catchment, have been observed to feed intensively on veligers of the exotic bivalve Limnoperna fortunei. 2.,To assess the effects of this dietary shift on the growth of P. lineatus, 28-day laboratory experiments were carried out feeding newly hatched P. lineatus larvae with three diets: zooplankton artificially enriched with L. fortunei veligers; natural zooplankton; and zooplankton artificially enriched with cladocerans and copepods. The average length, weight and gut contents of the fish larvae were assessed weekly and metabolic rates of fish larvae were measured. 3.,Proportions of veligers in gut contents were always higher than those in the experimental diet: 100, 76 and 21% for veliger-enriched, natural and low-veliger diets, respectively. Larvae fed a veliger-enriched diet grew to a significantly larger size than larvae fed the other two diets. In energetic balance comparisons using metabolic rates and prey energy content, all three diets were sufficient to support metabolism and growth. The greatest values of excess energy at the end of each week were in the veliger-enriched experiments. 4.,Feeding on veligers of L. fortunei significantly enhances the growth of P. lineatus larvae and supports the idea that this new and abundant resource is selectively preyed upon by P. lineatus during its larval stage. Higher growth rates may stem from the higher energy contents of veligers compared to crustaceans and/or from the lower energy costs of capturing slower prey. [source]

    Migratory Atlantic salmon as vectors for the transfer of energy and nutrients between freshwater and marine environments

    FRESHWATER BIOLOGY, Issue 1 2003
    Bror Jonsson
    SUMMARY 1.,Annual energy, carbon, nitrogen and phosphorus fluxes across the river mouth by Atlantic salmon were estimated for 18 years (1976,94) in the Norwegian River Imsa. The total energy content of the emigrating smolts in each year varied considerably with a mean value of 237 × 103 kJ. That of returning adults also varied between years with a mean value of 141 × 104 kJ. One-sea-winter salmon (grilse) made up 65% of the total energy content of the spawners in the river. Dead carcasses remaining in the river after spawning were estimated to have a mean annual energy content of 175 × 103 kJ. 2.,The net annual energy flux from the sea to the river varied between 48 × 103 kJ (1987) and 152 × 104 kJ (1989) with a mean of 616 × 103 kJ, and a coefficient of variation of 67%. Average net marine import of the returning adults was 83 × 104 kJ year,1 with a coefficient of variation of 52%. Mean annual export of C, N and P to sea by the smolts was 595, 131 and 22 kg, and by kelts 1535, 352 and 70 kg, respectively, whereas gross import via the adults was 3176 kg C, 735 kg N and 132 kg P. The annual flux across the river mouth was 1046 kg C, 253 kg N and 39 kg P. The net marine import were 1585 kg C, 371 kg N and 60 kg P. The net flux was estimated at 0.2% for nitrogen and 5% for phosphorus of the total river load. 3.,The energy flux caused by Atlantic salmon spawning in the River Imsa was relatively high because the general nutrient load in the river is low. Thus, even though most Atlantic salmon survive spawning, their contribution to the nutrient flux in the river is significant. [source]

    Within- and between-year variation in the juvenile survival of Common Guillemots Uria aalge

    IBIS, Issue 3 2007
    MICHAEL P. HARRIS
    We studied juvenile survival of 20 cohorts of Common Guillemot Uria aalge chicks colour-ringed on the Isle of May, Scotland, using both live observations at the colony and dead recoveries, allowing estimation of fidelity to the colony as well as survival. In this seabird, chicks leave the colony when only partly grown and are cared for by the male parent for several weeks afterwards. First-year survival varied strongly between cohorts, with a mean of 56% (range 30,91%). We did not identify any covariates which could explain this variation, whether relating to climate, population size or prey density. Survival was low during two regime shift episodes in the North Sea (1987,90 and 2000 onwards). Early hatched chicks were substantially more likely to survive than those hatching later in most years, whereas body condition at ringing had no detectable effect. Ringing recoveries indicated that mortality was highest in mid-winter, i.e. well after the cessation of paternal care. These results do not support the hypothesis that variation in prey quantity or energy content before fledging is a primary driver of variation in juvenile survival. Rather, it seems that chicks of high-quality parents are more likely to survive, as high-quality females tend to lay earlier in the season, and high-quality males presumably are better able to prepare their chicks to survive their first winter at sea. Very few (4%) Guillemots emigrated permanently before age 3 years, but from age 5 onwards 25,30% of birds annually left the colony or otherwise became unobservable. [source]

    Effect of the Environmental Factors on the Caloric Content of Benthic and Phytophilous Invertebrates in Neotropical Reservoirs in the Paraná State, Brazil

    INTERNATIONAL REVIEW OF HYDROBIOLOGY, Issue 3 2010
    Yara Moretto Bagatini
    Abstract The complexity of the relations between the organisms and the environment are reflected through the energy content. So we tested the hypothesis on body energy content variation in invertebrates and its relation with some environmental factors (season, habitat type, trophic status and trophic guild). We expected higher energy values for phytophilous fauna, rainy season, in reservoirs with higher trophic levels and for herbivorous invertebrates. The results showed the influence of seasonality and trophic status of the reservoir on the energy content of invertebrates, which was higher in the rainy season and in the mesotrophic reservoirs, due to the input of allochthonous material during this season, confirming our initial prediction. A higher caloric content was recorded for carnivorous and detritivorous invertebrates. The differences between the trophic guilds were primarily related to the opportunistic feeding behavior, which may be considered as one of the main factors controlling the energy flow of benthic and phytophilous invertebrates. (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

    Predator size, prey size and threshold food densities of diving ducks: does a common prey base support fewer large animals?

    JOURNAL OF ANIMAL ECOLOGY, Issue 5 2009
    Samantha E. Richman
    Summary 1. Allometry predicts that a given habitat area or common prey biomass supports fewer numbers of larger than smaller predators; however, birds from related taxa or the same feeding guild often deviate from this pattern. In particular, foraging costs of birds may differ among locomotor modes, while intake rates vary with accessibility, handling times and energy content of different-sized prey. Such mechanisms might affect threshold prey densities needed for energy balance, and thus relative numbers of different-sized predators in habitats with varying prey patches. 2. We compared the foraging profitability (energy gain minus cost) of two diving ducks: smaller lesser scaup (Aythya affinis, 450,1090 g) and larger white-winged scoters (Melanitta fusca, 950,1800 g). Calculations were based on past measurements of dive costs with respirometry, and of intake rates of a common bivalve prey ranging in size, energy content and burial depth in sediments. 3. For scaup feeding on small prey <12 mm long, all clams buried deeper than 5 cm were unprofitable at realistic prey densities. For clams buried in the top 5 cm, the profitability threshold decreased from 216 to 34 clams m,2 as energy content increased from 50 to 300 J clam,1. 4. For larger scoters feeding on larger prey 18,24 mm long, foraging was profitable for clams buried deeper than 5 cm, with a threshold density of 147 m,2 for clams containing 380 J clam,1. For clams <5 cm deep, the threshold density decreased from 86 to 36 clams m,2 as energy content increased from 380 to 850 J clam,1. If scoters decreased dive costs by swimming with wings as well as feet (not an option for scaup), threshold prey densities were 11,12% lower. 5. Our results show that threshold densities of total prey numbers for different-sized ducks depend on prey size structure and depth in the sediments. Thus, heterogeneity in disturbance regimes and prey population dynamics can create a mosaic of patches favouring large or small predators. Whether a given area or total prey biomass will support greater numbers of larger or smaller predators will vary with these effects. [source]

    Sex differences in grey seal diet reflect seasonal variation in foraging behaviour and reproductive expenditure: evidence from quantitative fatty acid signature analysis

    JOURNAL OF ANIMAL ECOLOGY, Issue 3 2007
    CARRIE A. BECK
    Summary 1Intraspecific variation in diet can be an important component of a species niche breadth. We tested the hypothesis that sex differences in seasonal foraging behaviour and energy storage of sexually size dimorphic grey seals Halichoerus grypus (Fabrisius 1971) are reflected in differences in the diet and niche breadth. Diet composition was estimated for 496 adult (226 males, 270 females) and 91 juvenile (46 males/45 females; all 6 months old) grey seals sampled between 1993 and 2000 using quantitative fatty acid signature analysis. Niche breadth and overlap were estimated using the Shannon,Weaver diversity index (H,) and the Morisita,Horn index (CH), respectively. 2Sand lance Ammodytes dubius (Reinhardt 1837) and redfish Sebastes sp. (Cuvier 1829) accounted for a high proportion of the diet in both sexes and age groups. However, the diets of adult males were significantly more diverse across all seasons (H,: males 0·36 ± 0·007 vs. females 0·28 ± 0·007) and less energy dense in spring (male 5·3 ± 0·07 kJ g,1 vs. females 5·6 ± 0·09 kJ g,1) than those of adult females. 3Season and sex explained most of the observed variation in adult diets, but there were significant sex,season interactions. These differences were most evident during the post-breeding (spring) foraging period when energy acquisition is important to female recovery of nutrient stores needed to support pregnancy. Females selected fewer and higher quality prey species in spring than males. 4There were no sex differences in the diets of juvenile grey seals. Although many of the species overlapped with those eaten by adults, juvenile niche breadth (H,: 0·41 ± 0·014, n = 91) was significantly broader than that of adults (H,: 0·30 ± 0·011, n = 115). Juvenile diets were also of lower energy density (5·3 ± 0·04 kJ g,1) than those of adults (5·6 ± 0·09 kJ g,1), suggesting less selectivity in these young and relatively naïve predators. 5Sex-specific seasonal changes in diet correspond to seasonal changes in diving behaviour and rate of body energy accumulation of adult males and females. Sex-specific reproductive requirements appear to be a primary factor generating the intraspecific variation in the seasonal foraging ecology of this large marine carnivore. However, sex differences in the breadth and energy content of diets also suggest the influence of body-size dimorphism as a factor shaping the diet of this species. [source]

    Untersuchungen zum Einfluß einer Xylanaseergänzung in Legehennenrationen auf Weizenbasis 2.

    JOURNAL OF ANIMAL PHYSIOLOGY AND NUTRITION, Issue 1-2 2000
    Mitteilung: Auswirkungen auf die Leistungsparameter
    Summary The influence of a xylanase supplement on performance of laying hens fed different energy-graded, wheat-based rations was tested in a 12-week trial. Two varieties of wheat with different extraction viscosity were selected. In addition to the control ration, three test rations with reduced energy contents of ,3, ,6, and ,9% were used. Sixteen groups, each consisting of 30 hens were kept in single cages. At the beginning of the experiment hens were 24 weeks old. Single eggmass and daily eggmass production showed a statistically significant difference. This was not caused by the enzyme supplement or the energy content, but by the variety of wheat. Interaction effects between variety of wheat, enzyme supplement and energy content became obvious with regard to the yolk colour. The influence of the enzyme on the yolk colour is positive and statistically highly significant. Thus, the addition of xylanase to wheat-based rations does not affect the performance parameters of laying hens positively. Zusammenfassung In einem zwölfwöchigem Leistungsversuch wurde der Einfluß einer Xylanaseergänzung in Legehennenrationen auf Weizenbasis mit abgestuftem Energiegehalt auf die Leistungsparameter untersucht. Dazu wurden zwei Weizensorten (Alidos + Caprimus) mit unterschiedlicher Extraktviskosität ausgesucht und neben den jeweiligen Kontrollrationen drei Versuchsrationen mit abgestuftem Energiegehalt (,3%, ,6%, ,9%) eingesetzt. Den 16 Versuchsgruppen waren jeweils 30 Legehennen zugeordnet, die bei Versuchsbeginn 24 Lebenswochen alt waren. Es handelte sich um eine Einzelkäfigaufstallung. Statistisch signifikante Unterschiede ergaben sich bei der Einzeleimasse und der täglichen Eimasseproduktion, die sich jedoch weder dem Enzymzusatz noch dem Energiegehalt zuordnen ließen, sondern durch die Weizensorte bedingt waren. Es zeigten sich Wechselwirkungen zwischen Weizensorte, Enzymsupplementierung und Energiegehalt auf die Dotterfarbe. Es war ein statistisch hochsignifikanter positiver Enzymeinfluß auf die Dotterfarbe zu erkennen. Insgesamt gesehen, zeigte sich auch in diesem Legehennenversuch keine positive Wirkung der Xylanaseergänzung auf die Leistungsparamter zu Rationen auf Weizenbasis. [source]

    Effect of inclusion of blue-green algae meal on growth and accumulation of microcystins in gibel carp (Carassius auratus gibelio)

    JOURNAL OF APPLIED ICHTHYOLOGY, Issue 1 2006
    M. Zhao
    Summary Six isonitrogenous (crude protein content: 38%) and isoenergetic (gross energy content: 17 kJ g,1) diets were formulated to investigate the effects of inclusion of blue-green algae meal on gibel carp (Carassius auratus gibelio). In each diet, 15% of the protein was supplied by fishmeal; the remainder was supplied by soybean meal and blue-green algae meal. Diet 1 was used as control with no blue-green algae meal whereas the content in diets 2,6 was 15.15, 29.79, 44.69, 59.58 and 74.48%, respectively. Each diet was fed to five groups of gibel carp for 12 weeks in a flow-through system. Final body weight and specific growth rate (SGR) of fish fed diet 5 were significantly lower than the control diet (P < 0.05). Mortality of gibel carp increased with increase in algae meal inclusion (P < 0.05), but there was no significant difference between fish fed diets 3,6 (P > 0.05). Feed conversion efficiency (FCE) decreased with the increase in algae meal inclusion (P < 0.05). Fish-fed diet 6 showed the highest feeding rate (P < 0.05), while there were no significant differences among the other groups (P > 0.05). Apparent digestibility coefficient of dry matter, protein, and energy decreased with increasing algae meal inclusion in the diets (P < 0.05). Aspartate aminotransferase (GOT) activity in the liver was not significantly different among groups (P > 0.05). Liver alanine aminotransferase (GPT) activity of fish-fed diets 4, 5 and 6 was significantly lower than the control diet (diet 1; P < 0.05). Microcystins in the muscle, liver, gallbladder, and spleen increased with increasing algae inclusion (P < 0.05). [source]

    Growth and feed utilization in two strains of gibel carp, Carassius auratus gibelio: paternal effects in a gynogenetic fish

    JOURNAL OF APPLIED ICHTHYOLOGY, Issue 2 2001

    Gibel carp (Carassius auratus gibelio Bloch) is a natural gynogenetic fish which requires sperm of the same or related species to activate egg development. The eggs of one gibel carp were divided into two batches. One batch was ,fertilized' with sperm from gibel carp (strain DD), and the other ,fertilized' with sperm from red common carp (Cyprinus carpio red variety) (strain DR). The juveniles were transferred to the laboratory 36 days post-hatch. Triplicate groups of each strain were fed a formulated diet at either 3% or satiation ration for 8 weeks. At both the restricted and satiation rations, specific growth rate was significantly higher in strain DR than in strain DD. At the 3% ration, there was no significant difference in feeding rate or feed conversion efficiency between the two strains. At the satiation ration, strain DR had a significantly lower feeding rate but higher feed conversion efficiency than strain DD. At the satiation ration, strain DR had a significantly lower intake protein, but higher recovered protein than strain DD. There was no significant difference in faecal protein loss between the two strains. At the 3% ration, strain had no significant effects on intake protein, faecal protein or recovered protein. Neither faecal energy loss nor recovered energy was affected by strain or ration. At both the 3% and satiation ration, final body contents of dry matter and lipid were significantly lower in strain DR than strain DD, while there was no significant difference in protein and energy content between the two strains at either ration level. The results suggested that gibel carp ,fertilized' with sperm of common carp grew faster than those ,fertilized' with sperm of gibel carp through increased feed conversion efficiency and protein retention. [source]

    Food energy content influences food portion size estimation by nutrition students

    JOURNAL OF HUMAN NUTRITION & DIETETICS, Issue 3 2010
    C. C. Japur
    Abstract Background:, Food portion size estimation involves a complex mental process that may influence food consumption evaluation. Knowing the variables that influence this process can improve the accuracy of dietary assessment. The present study aimed to evaluate the ability of nutrition students to estimate food portions in usual meals and relate food energy content with errors in food portion size estimation. Methods:, Seventy-eight nutrition students, who had already studied food energy content, participated in this cross-sectional study on the estimation of food portions, organised into four meals. The participants estimated the quantity of each food, in grams or millilitres, with the food in view. Estimation errors were quantified, and their magnitude were evaluated. Estimated quantities (EQ) lower than 90% and higher than 110% of the weighed quantity (WQ) were considered to represent underestimation and overestimation, respectively. Correlation between food energy content and error on estimation was analysed by the Spearman correlation, and comparison between the mean EQ and WQ was accomplished by means of the Wilcoxon signed rank test (P < 0.05). Results:, A low percentage of estimates (18.5%) were considered accurate (±10% of the actual weight). The most frequently underestimated food items were cauliflower, lettuce, apple and papaya; the most often overestimated items were milk, margarine and sugar. A significant positive correlation between food energy density and estimation was found (r = 0.8166; P = 0.0002). Conclusions:, The results obtained in the present study revealed a low percentage of acceptable estimations of food portion size by nutrition students, with trends toward overestimation of high-energy food items and underestimation of low-energy items. [source]

    Making an informed choice in the catering environment: what do consumers want to know?

    JOURNAL OF HUMAN NUTRITION & DIETETICS, Issue 6 2009
    D. Mackison
    Abstract Background:, Eating outside the home is common in the UK, but it remains difficult for consumers to make informed choices based on menu information. The present study examines the reported preferences for the provision of nutrition (salt, fat and energy) and ingredient information in six types of UK catering outlets. Methods:, Participants completed a short postal survey, assessing their frequency of dining at specific catering establishments as well as their desire to see nutrition and ingredient information. Results:, The responses from 786 adults aged ,18 years (of whom 65% claimed to be ,motivated to eat a healthy diet') indicated that over 40% reported eating at a catering outlet at least once a week. Over half said that they would wish to see information on ingredients and the salt content of menu items at all venues. Preference for information on energy and fat content was less popular and varied in the range 42,56% for energy and 47,59% for fat. It is notable that 43% of respondents said they would welcome information on energy content of menu items in restaurants. Conclusion:, A significant proportion of consumers wish to see information on the ingredients and nutrition composition on menu items for sale in UK catering outlets. Such information is likely to raise an awareness and understanding of healthy food choices and assist the population in making informed choices about healthy eating. [source]

    EFFECTS OF INULIN AND BULKING AGENTS ON SOME PHYSICOCHEMICAL, TEXTURAL AND SENSORY PROPERTIES OF MILK CHOCOLATE

    JOURNAL OF TEXTURE STUDIES, Issue 5 2009
    HANNANEH FARZANMEHR
    ABSTRACT Chocolates are favorite foodstuffs with high sugar contents. Therefore, in the present study, the production of a low-sugar milk chocolate with prebiotic properties is evaluated. Various ratios of inulin (IN), polydextrose (PD) and maltodextrin (MD) along with sucralose (0.04% w/w) were used instead of sugar. Fifteen formulations were examined to determine some physicochemical, mechanical and sensory properties in order to find their optimum ratios. In general, formulations with high ratios of PD and MD were moister and softer than control. The lowest moisture content and highest hardness were observed for the moderate ratios. In addition, MD induced the least desirable sensorial effects, whereas PD and IN pronouncedly improved the overall acceptability. The optimum applicable range for IN, PD and MD were 14,32% and 71,84%, 7,26% and 67,77%, and 0,20% of sugar substitutes, respectively. Our findings on simultaneous fat and sugar reductions also indicated the possibility of fat cut up to 5% in comparison to previous fat content. PRACTICAL APPLICATIONS In this paper, we have reported the influences of inulin (IN) as a prebiotic as well as polydextrose (PD) and maltodextrin (MD) as bulking agents on physicochemical, energy content, texture and sensory properties of milk chocolate using simplex lattice mixture design. To the best of our knowledge, this is the first report in this field with very interesting results and practical applicability. Moreover, our findings showed that the use of aforementioned ingredients instead of sugar could lead to production of low-calorie milk chocolate without having the undesirable textural and physiological effects on the product and consumers. Moreover, the simplex lattice mixture design was found a very useful technique for finding optimum ratios of sugar replacers in formulation. [source]

    Estimation of metabolisable energy content of date pit and its effect on lipid and protein oxidation in broiler chicks

    JOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 13 2009
    Mojtaba Zaghari
    Abstract BACKGROUND: Two experiments were conducted to evaluate date pit as a feed ingredient in broiler chick diets. In the first experiment, apparent metabolisable energy (AME) of date pit was determined using 72 Ross (308) broiler chicks. Broiler chicks received experimental diets from 25 to 30 days of age. Two diets were fed: diet 1, basal diet and diet 2, 60% basal diet + 40% date pit. Date pit ileal AMEn was estimated to be 704 kcal kg,1. The second study was conducted to evaluate the AMEn value obtained and also the effectiveness of using a commercial multi-enzyme in diets containing date pit. Diets with three levels of date pit (10, 20 and 30% date pit) with or without enzyme supplementation were fed to broiler chicks from day old to 42 days of age. RESULTS: Chicks receiving different levels of dietary date pit had comparable body weight to those fed on corn,soybean meal diet. Both date pit levels and enzyme supplementation had a significant effect on feed conversion ratio. Plasma total antioxidant levels of positive control were significantly lower than the experimental diets. CONCLUSION: Results obtained in our study suggested that date pit could be used as a feed ingredient in the diet of broiler chicks without any negative effect on performance. Furthermore, date pit may have beneficial effects on plasma antioxidant status in broiler chicks. Copyright © 2009 Society of Chemical Industry [source]

    Factors affecting the predation of otter (Lutra lutra) on European pond turtle (Emys orbicularis)

    JOURNAL OF ZOOLOGY, Issue 2 2006
    J. Lanszki
    Abstract In this case study, the ecological background of an unusual hunting behaviour was investigated, when otters Lutra lutra preyed upon European pond turtles Emys orbicularis in a Hungarian fish pond system during an 18-month period. Predation on turtle was found only during cold periods (established by spraint analysis and also by the collection of 182 turtle carcasses in 2003). The relationship was not close between fish availability and turtle consumption (rP=,0.325, P=0.19). The crude protein content of the turtle head and leg was higher than that of fish, frog and turtle body, whereas the energy content of the samples was similar. The mean body weight of the killed turtles (460 g) fell within the range of the optimal prey size of the otter. Turtles were used as cache foods by otters during extreme environmental conditions (as in the long winter), but occurred only rarely as buffer foods during moderate winter. In fish ponds, the conservation of the coexistent otter and turtle depends on pond management. The maintenance of a higher fish availability in ponds during winter makes it possible to avoid the need to acquire a proper hunting technique on turtle, indicated by the scarcity of primary fish food. [source]

    Activation of large lons in FT-ICR mass spectrometry

    MASS SPECTROMETRY REVIEWS, Issue 2 2005
    Julia Laskin
    Abstract The advent of soft ionization techniques, notably electrospray and laser desorption ionization methods, has enabled the extension of mass spectrometric methods to large molecules and molecular complexes. This both greatly extends the applications of mass spectrometry and makes the activation and dissociation of complex ions an integral part of these applications. This review emphasizes the most promising methods for activation and dissociation of complex ions and presents this discussion in the context of general knowledge of reaction kinetics and dynamics largely established for small ions. We then introduce the characteristic differences associated with the higher number of internal degrees of freedom and high density of states associated with molecular complexity. This is reflected primarily in the kinetics of unimolecular dissociation of complex ions, particularly their slow decay and the higher energy content required to induce decomposition,the kinetic shift (KS). The longer trapping time of Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) significantly reduces the KS, which presents several advantages over other methods for the investigation of dissociation of complex molecules. After discussing general principles of reaction dynamics related to collisional activation of ions, we describe conventional ways to achieve single- and multiple-collision activation in FT-ICR MS. Sustained off-resonance irradiation (SORI),the simplest and most robust means of introducing the multiple collision activation process,is discussed in greatest detail. Details of implementation of this technique, required control of experimental parameters, limitations, and examples of very successful application of SORI-CID are described. The advantages of high mass resolving power and the ability to carry out several stages of mass selection and activation intrinsic to FT-ICR MS are demonstrated in several examples. Photodissociation of ions from small molecules can be effected using IR or UV/vis lasers and generally requires tuning lasers to specific wavelengths and/or utilizing high flux, multiphoton excitation to match energy levels in the ion. Photodissociation of complex ions is much easier to accomplish from the basic physics perspective. The quasi-continuum of vibrational states at room temperature makes it very easy to pump relatively large amounts of energy into complex ions and infrared multiphoton dissociation (IRMPD) is a powerful technique for characterizing large ions, particularly biologically relevant molecules. Since both SORI-CID and IRMPD are slow activation methods they have many common characteristics. They are also distinctly different because SORI-CID is intrinsically selective (only ions that have a cyclotron frequency close to the frequency of the excitation field are excited), whereas IRMPD is not (all ions that reside on the optical path of the laser are excited). There are advantages and disadvantages to each technique and in many applications they complement each other. In contrast with these slow activation methods, the less widely appreciated activation method of surface induced dissociation (SID) appears to offer unique advantages because excitation in SID occurs on a sub-picosecond time scale, instantaneously relative to the observation time of any mass spectrometer. Internal energy deposition is quite efficient and readily adjusted by altering the kinetic energy of the impacting ion. The shattering transition,instantaneous decomposition of the ion on the surface,observed at high collision energies enables access to dissociation channels that are not accessible using SORI-CID or IRMPD. Finally, we discuss some approaches for tailoring the surface to achieve particular aims in SID. © 2004 Wiley Periodicals, Inc., Mass Spec Rev 24:135,167, 2005 [source]

    Constraints on modified gravity from the observed X-ray luminosity function of galaxy clusters

    MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 2 2009
    David Rapetti
    ABSTRACT We use measurements of the growth of cosmic structure, as inferred from the observed evolution of the X-ray luminosity function (XLF) of galaxy clusters, to constrain departures from general relativity (GR) on cosmological scales. We employ the popular growth rate parameterization, ,m(z),, for which GR predicts a growth index ,, 0.55. We use observations of the cosmic microwave background (CMB), type Ia supernovae (SNIa) and X-ray cluster gas mass fractions (fgas), to simultaneously constrain the expansion history and energy content of the Universe, as described by the background model parameters: ,m, w and ,k, i.e. the mean matter density, the dark energy equation of state parameter and the mean curvature, respectively. Using conservative allowances for systematic uncertainties, in particular for the evolution of the mass,luminosity scaling relation in the XLF analysis, we find ,= 0.51+0.16,0.15 and ,m= 0.27 ± 0.02 (68.3 per cent confidence limits), for a flat cosmological constant, cold dark matter (,CDM) background model. Allowing w to be a free parameter, we find ,= 0.44+0.17,0.15. Relaxing the flatness prior in the ,CDM model, we obtain ,= 0.51+0.19,0.16. When in addition to the XLF data we use the CMB data to constrain , through the ISW effect, we obtain a combined constraint of ,= 0.45+0.14,0.12 for the flat ,CDM model. Our analysis provides the tightest constraints to date on the growth index. We find no evidence for departures from GR on cosmological scales. [source]

    Turbulent gas motions in galaxy cluster simulations: the role of smoothed particle hydrodynamics viscosity

    MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 3 2005
    K. Dolag
    ABSTRACT Smoothed particle hydrodynamics (SPH) employs an artificial viscosity to properly capture hydrodynamic shock waves. In its original formulation, the resulting numerical viscosity is large enough to suppress structure in the velocity field on scales well above the nominal resolution limit, and to damp the generation of turbulence by fluid instabilities. This could artificially suppress random gas motions in the intracluster medium (ICM), which are driven by infalling structures during the hierarchical structure formation process. We show that this is indeed the case by analysing results obtained with an SPH formulation where an individual, time-variable viscosity is used for each particle, following a suggestion by Morris & Monaghan. Using test calculations involving strong shocks, we demonstrate that this scheme captures shocks as well as the original formulation of SPH, but, in regions away from shocks, the numerical viscosity is much smaller. In a set of nine high-resolution simulations of cosmological galaxy cluster formation, we find that this low-viscosity formulation of SPH produces substantially higher levels of turbulent gas motions in the ICM, reaching a kinetic energy content in random gas motions (measured within a 1-Mpc cube) of up to 5,30 per cent of the thermal energy content, depending on cluster mass. This also has significant effects on radial gas profiles and bulk cluster properties. We find a central flattening of the entropy profile and a reduction of the central gas density in the low-viscosity scheme. As a consequence, the bolometric X-ray luminosity is decreased by about a factor of 2. However, the cluster temperature profile remains essentially unchanged. Interestingly, this tends to reduce the differences seen in SPH and adaptive mesh refinement simulations of cluster formation. Finally, invoking a model for particle acceleration by magnetohydrodynamics waves driven by turbulence, we find that efficient electron acceleration and thus diffuse radio emission can be powered in the clusters simulated with the low-viscosity scheme provided that more than 5,10 per cent of the turbulent energy density is associated with fast magneto-sonic modes. [source]

    Hydration and health: a review

    NUTRITION BULLETIN, Issue 1 2010
    B. Benelam
    Summary Water is essential for life and maintaining optimal levels of hydration is important for humans to function well. Water makes up a large proportion of our body weight (60% on average), distributed between the intracellular (inside cells) and extracellular (water in the blood and in between cells) compartments. Water is the major component of body fluids, such as blood, synovial fluid (fluid in the joints), saliva and urine, which perform vital functions in the body. The concentration of solutes (osmolality) in body fluids is closely controlled, and even very small changes in osmolality trigger a physiological response; either to increase body water by reducing urinary output and stimulating thirst; or to excrete excess water as urine. Generally, body water is maintained within narrow limits. However, if water losses are not sufficiently replaced, dehydration occurs. Extreme dehydration is very serious and can be fatal. More mild dehydration (about 2% loss of body weight) can result in headaches, fatigue and reduced physical and mental performance. It is also possible to consume too much water and in rare cases this can result in hyponatraemia (low levels of sodium in the blood). We can get water from almost all drinks and from some foods in the diet. Food provides about 20% on average and this could vary widely depending on the types of food chosen. We also get water from all the drinks we consume, with the exception of stronger alcoholic drinks like wines and spirits. All these can contribute to dietary water, but also have other effects on health both positive and negative. The major concerns with regards to beverages are their energy content and their effect on dental health. With obesity levels continuing to increase it is important for many in the population to control their energy intake, and drinks as well as foods must be considered for their energy content. With regards to dental health, there are two concerns; dental caries and dental erosion. Dental caries are caused by a reduction in pH due to bacterial fermentation of carbohydrates, and so the frequency of consumption of drinks containing sugars is a concern for risk of caries. Dental erosion occurs at a lower pH and is caused by the consumption of acidic foods and drinks, in particular, citrus juices and soft drinks containing acids. Individual water needs vary widely depending on many factors including body size and composition, the environment and levels of physical activity. Thus it is very difficult to make generic recommendations about the amount of water to consume. The FSA currently recommends drinking about 1.2 litres per day (about 6,8 glasses). [source]

    Junk-food in marine ecosystems

    OIKOS, Issue 7 2008
    Henrik Österblom
    The abundance and availability of food are critical determininants of reproductive success and population dynamics of marine top predators. However, recent work has indicated that the quality of the food may also be critically important for some marine predators. The ,junkfood hypothesis' was originally suggested as a potential explanation for a dramatic population decline of Stellers sea lions Eumetopias jubatus in the Gulf of Alaska. According to the hypothesis, a dietary switch to prey of low energy content led to detrimental effects on the population of sea lions. A number of observations indicate that the hypothesis is relevant for several population parameters. Recent work on piscivorous seabirds has provided substantial evidence indicating the relevance of this hypothesis in food webs in e.g. the North Pacific, the North Sea and the Baltic Sea. The emergence of ,junk-food' in these systems may be coupled to large scale changes in climatological and oceanographic forcing, although predation, fishing and competition provide additional plausible hypotheses. It may be possible to predict which kinds of animals will be particularly sensitive to food quality; these seem to be species with limited ability to carry food loads, with energetically-expensive foraging behaviour, and with digestive anatomy evolved to minimize mass at the cost of digestive efficiency. This review suggests that the junk-food hypothesis is a highly relevant factor in relation to sustaining ecosystem resilience, and is an important consideration in ecosystem management. Sustaining healthy populations of marine top-predators requires an understanding of the role of food quality, in addition to food abundance and availability. [source]

    Lower energy content of human milk than calculated using conversion factors

    PEDIATRICS INTERNATIONAL, Issue 1 2005
    Satoko Hosoi
    Abstract,Background:,Bodyweight gain of formula-fed babies is usually higher than that of breast-fed ones. The energy content of human milk is usually quantified not by direct measurement but by calculation based on The Standard Tables of Food Composition in Japan. For this study, the energy of human milk was quantified in two ways, using a direct measurement and a calculation method. Methods:,A total of 227 milk samples (192 colostrum, 21 transitional milk, and 14 mature milk) were collected from 114 healthy women. Energy of the whole milk was measured by ballistic bomb calorimetry. The content of protein, fat, and carbohydrate was determined by direct measurement methods. Energy of the milk was also calculated according to the indices in The Standard Tables. Results:,The mean value for all milk samples of directly measured energy was significantly lower than that of the calculated energy (58.1 ± 8.1 vs. 64.5 ± 10.6 kcal/100 g, n = 227, P < 0.05). Similar results were observed in colostrum and transitional milk but not in mature milk. Measured energy in mature milk was significantly higher than that in colostrum (64.2 ± 3.6 vs. 57.1 ± 8.0 kcal/100 g, P < 0.05). Protein concentration in mature milk was significantly lower than that in colostrum (1.4 ± 0.4 vs. 2.2 ± 0.7 g/100 g, P < 0.05). Conclusions:,The measured energy content of human milk was lower than the calculated energy based upon the Standard Tables, suggesting that formula milk contains excessive energy. [source]

    Infant sex predicts breast milk energy content

    AMERICAN JOURNAL OF HUMAN BIOLOGY, Issue 1 2010
    Camille E. Powe
    During human evolutionary history, and for many around the world, breast milk is the primary source of nutritional energy for infants. Variation in breast milk quality might logically have important effects on infant health, growth, and development, yet the sources of this variation remain largely unelucidated. We quantified nutrient and energy content of breast milk from 25 healthy, well-nourished Massachusetts mothers with infants aged 2,5 months. We examined several potential sources of variation in milk quality, particularly feeding patterns, infant sex, and maternal breast growth during pregnancy. After controlling for time since last feeding, a known correlate of milk composition, we found that mothers of male infants produced milk that had 25% greater energy content than mothers of female infants (P < 0.001). Change in maternal bra cup size during pregnancy was associated with 16.17 kcal/100 ml greater energy content of milk (P = 0.009), but was not significant after taking infant sex into account. Greater nutritional investment in sons may account for the greater observed growth rates in male compared to female infants. Am. J. Hum. Biol. 2010. © 2009 Wiley-Liss, Inc. [source]

    Plant foods consumed by Pan: Exploring the variation of nutritional ecology across Africa

    AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY, Issue 3 2010
    Gottfried Hohmann
    Abstract It has been shown that differences in resource density and nutrient supply affect variation in ranging patterns, habitat use, and sociality. Among nonhuman primates, chimpanzees (Pan troglodytes) and bonobos (P. paniscus) have often been used as models for the link between social system and habitat ecology. Field reports suggest that resource density is higher in habitats occupied by bonobos (compared to chimpanzee habitats), and in the West (compared to the East) of the range of chimpanzees. In this study we compared diet quality at the level of species and populations using information from nutritional analyses of fruit and leaves consumed by chimpanzees (three) and bonobos (one population). Quality of plant foods was assessed on the basis of a) the concentration of macronutrients, fiber, and anti-feedants, and b) associations of different nutrient components. Overall plant samples collected at each site differed in terms of macronutrient content. However, nutritious quality and gross energy content of food samples were similar suggesting that dietary quality reflects selectivity rather than habitat ecology. The quality of plant foods consumed by bonobos was within the range of chimpanzees and the quality of plant foods consumed by western chimpanzees was not higher than that of eastern chimpanzees. While the results showed significant variation across forests inhabited by Pan, they did not match with geographical patterns between and within Pan species as proposed in previous studies. This suggests that the nutritional quality of the habitat is not always a reliable predictor of the quality of the diet. Am J Phys Anthropol 2010. © 2009 Wiley-Liss, Inc. [source]

    The importance of ingestion rates for estimating food quality and energy intake

    AMERICAN JOURNAL OF PRIMATOLOGY, Issue 10 2006
    Oliver Schülke
    Abstract Testing ecological or socioecological models in primatology often requires estimates of individual energy intake. It is a well established fact that the nutrient content (and hence the energy content) of primate food items is highly variable. The second variable in determining primate energy intake, i.e., the ingestion rate, has often been ignored, and few studies have attempted to estimate the relative importance of the two predictors. In the present study individual ingestion rates were measured in two ecologically very different populations of Hanuman langurs (Semnopithecus entellus) at Jodhpur, India, and Ramnagar, Nepal. Protein and soluble sugar concentrations in 50 and 100 food items. respectively, were measured using standardized methods. Variation in ingestion rates (gram of dry matter per minute) was markedly greater among food items than among langur individuals in both populations, but did not differ systematically among food item categories defined according to plant part and age. General linear models (GLMs) with ingestion rate, protein, and soluble sugar content explained 40,80% of the variation in energy intake rates (kJ/min). The relative importance of ingestion rates was either similar (Ramnagar) or much greater (Jodhpur) than the role of sugar and/or protein content in determining the energy intake rates of different items. These results may impact socioecological studies of variation in individual energy budgets, investigations of food choice in relation to chemical composition or sensory characteristics, and research into habitat preferences that measures habitat quality in terms of abundance of important food sources. We suggest a definition of food quality that includes not only the amount of valuable food contents (energy, vitamins, and minerals) and the digestibility of different foods, but also the rate at which the food can be harvested and processed. Such an extended definition seems necessary because time may constrain primates when feeding competition is intense and foraging is risk-prone. Am. J. Primatol. 68:951,965, 2006. © 2006 Wiley-Liss, Inc. [source]

    The effects of polymorphisms in the DGAT1, leptin and growth hormone receptor gene loci on body energy, blood metabolic and reproductive traits of Holstein cows

    ANIMAL GENETICS, Issue 1 2009
    G. Oikonomou
    Summary The objective of this study was to examine the impact of polymorphisms in the acyl-CoA:diacylglycerol acyltransferase (DGAT1), leptin and growth hormone receptor genes on body energy (body condition score, total body energy content and cumulative effective energy balance) and blood metabolic traits (levels of ,-hydroxybutyrate, glucose and non-esterified fatty acids), measured once before the first calving and then repeatedly throughout first lactation in 497 Holstein cows. The influence of the same polymorphisms on cow reproductive performance and health during the first and second lactations was also assessed. Several reproductive traits were considered including interval, conception and insemination traits, as well as incidence of metritis and reproductive problems. Genotyping was performed using PCR-RFLP (DGAT1, leptin) or allele-specific PCR (growth hormone receptor). For each locus, the effect of allele substitution on body energy and blood metabolic traits was estimated using random regression models. The same effect on reproductive traits was assessed with single-trait mixed linear models. Significant (P < 0.05) effects on specific reproductive traits were observed. DGAT1 and growth hormone receptor alleles responsible for significant increases in milk production were found to have an adverse effect on reproduction, while the leptin allele responsible for significant increase in milk production was linked to marginally increased metritis frequency. Furthermore, the three studied loci were also found to significantly (P < 0.05) affect certain body energy and blood metabolic traits. Several associations are published for the first time, but these should be confirmed by other investigators before the polymorphisms are used in gene-assisted selection. [source]