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Nutrient Requirements (nutrient + requirement)
Selected AbstractsNutrient requirements of ephemeral plant species from wet, mesotrophic soilsJOURNAL OF VEGETATION SCIENCE, Issue 3 2001Emiel; Brouwer van der Meijden (1996) Abstract. Nanocyperion plant communities occur on wet, more or less nutrient-poor and sparsely vegetated soils in temperate climates and are characterized by tiny, very shortlived plant species. Most of these have become locally extinct. It is generally assumed that drainage and eutrophication were the most important reasons for this decrease. However, chemical analysis of soil pore water from plots on growth sites of these ephemerals showed that phosphorus availability was relatively high. In a greenhouse experiment, the growth of ephemeral species was strongly limited by the amount of available phosphorus, whereas there was little or no limitation to the growth of other plant species from this habitat. At low phosphorus concentrations, the ephemeral species reached their reproductive phase within the same period, but showed a strong reduction in the amount of flowers that were produced. We concluded that ephemeral species in particular require a minimum amount of phosphorus for reproduction. Other species on nutrient-poor, wet soils have a longer life span and can postpone flowering in nutrient-poor soils. In contrast to other short-lived plant species from the same habitat, the growth of ephemeral species was barely stimulated by enhanced nitrogen availability. Apparently, the ephemerals are adapted to low nitrogen concentrations. The occurrence on nitrogen-poor and relatively phosphorus-rich soils suggests that this community may be very sensitive to nitrogen deposition. Reduced phosphorus availability below the minimum requirements of ephemerals, for example after acidification or the exclusion of human activities, has possibly contributed to the decrease of ephemeral plant species. [source] Improvement of a fed-batch process for high level xylanase production by a Bacillus strainJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 5 2001Gerhard Schneider Abstract In this paper, the improvement of a fed-batch fermentation from the point of view of an industrial xylanase production process is described. The Bacillus strain chosen for this study is able to produce high quantities of a xylanase that is suitable to be used as bleach boost agent in chlorine-free bleaching sequences of paper pulp. It was found that xylo-oligosaccharides (hydrolysis products from xylan by xylanase action) were indispensable for induction of the enzyme synthesis, but that their presence in quantities of only 0.1,g,dm,3 xylose equivalents led to catabolite repression. A substrate-limited fed-batch process, that is the most adapted, was furthermore improved with regard to nutrient requirement of the microorganism, especially the nitrogen source. A process with constant supply of a culture medium containing xylan, peptone and mineral nitrogen was able to produce 20,240,nkat,cm,3 with a productivity of 910,nkat,cm,3,h,1, which places the process among the best ever reported. © 2001 Society of Chemical Industry [source] Feed intake and growth performance of Senegalese sole (Solea senegalensis Kaup, 1858) fed diets with partial replacement of fish meal with plant proteinsAQUACULTURE RESEARCH, Issue 9 2010Joana M G Silva Abstract To be able to study nutrient requirement and utilization in any species, a diet supporting normal feed intake and growth equally well as a traditional fish meal-based diet is needed. Additionally the formulation of the diet should allow low levels of the nutrient under study. When studying the amino acid metabolism and requirements, one cannot rely on the fish meal-based diets as fish meal are nicely balanced according to requirements. Therefore the current study aimed to develop a plant protein-based diet (with low fish meal inclusion) to be used in the nutritional studies of Senegalese sole juveniles supporting feed intake and growth close to that obtained in a fish meal-based control feed. Two experiments were conducted to evaluate whether Senegalese sole juveniles would accept and utilize diets containing high plant protein inclusion. For testing the acceptance of high plant protein inclusion, two diets were formulated: a reference diet that contained fish meal as the main protein source (450 g kg,1 dry matter) whereas in the test diet, fish meal was substituted by a mixture of plant ingredients (soybean meal, corn and wheat gluten) with l -lysine supplementation. In order to improve the palatability, 50 g kg,1 squid meal was added to both diets. The indispensable amino acids (IAA) profile of the test diet was made similar to the control diet by adding crystalline amino acids. Further, automatic feeders were used to improve the feed intake. Fish (24 g initial body weight) were fed the diets for a period of 4 weeks. As fish accepted both diets equally well, a second study was undertaken to test the growth performance. Fish (6 g initial BW) were fed the diets for a period of 12 weeks. The use of automatic feeders to deliver the feed and the addition of both squid and balancing the indispensable amino acids resulted in growth performance and accretion not differing from the fish meal fed control. It can be concluded that juvenile Senegalese sole are able to grow and utilize high plant-protein diets when both diet composition and feeding regime are adequate for this species. [source] Challenges and opportunities in soil organic matter researchEUROPEAN JOURNAL OF SOIL SCIENCE, Issue 2 2009R. Lal Summary Soil organic matter (SOM) can be a source or sink for atmospheric CO2 depending on land use, and management of soil, vegetation and water resources. SOM is a source of atmospheric CO2, with the use of extractive farming practices that lead to a negative nutrient balance and exacerbate soil degradation. The historic loss of C from the SOM pool between the 1850s and 2000 is estimated at 78 ± 12 Gt compared with the emission of 270 ± 30 Gt from fossil fuel combustion. Despite its numerous direct and ancillary benefits, enhancing the SOM pool is a major challenge, especially in impoverished and depleted soils in harsh tropical climates. In addition to biophysical factors, there are also numerous social, economic and political constraints that limit increase in SOM pools. Conversion of plough-tillage to no-till farming, an important practice to enhance the SOM pool, is constrained by the limited access to herbicides and seed drill, and the competing uses of crop residues. Yet, enhancing the SOM pool is essential to restoring degraded soils, advancing food security and improving the environment. Important subjects among researchable topics include: assessing the rate of SOM accretion for a wide range of land use and management practices with reference to a baseline; evaluating the importance of biochar; measuring and predicting SOM at landscape and extrapolation to regional scale; establishing relationships between SOM and soil quality and agronomic productivity; determining on- and off-site effects of crop residues removal for ethanol/biofuel production; determining the fate of C in SOM translocated by erosional processes; evaluating nutrient requirements for increasing SOM in croplands; validating predictive models in tropical environments; and developing methodology for trading C credits. [source] Variability in the spawning habitat of Pacific sardine (Sardinops sagax) off southern and central CaliforniaFISHERIES OCEANOGRAPHY, Issue 6 2003Ronald J. Lynn Abstract The spatial pattern of sardine spawning as revealed by the presence of sardine eggs is examined in relation to sea surface temperature (SST) and mean volume backscatter strength (MVBS) measured by a 150 kHz acoustic Doppler current profiler (ADCP) during four spring surveys off central and southern California in 1996,99. Studies in other regions have shown that MVBS provides an excellent measure of zooplankton distribution and density. Zooplankton biomass as measured by survey net tows correlates well with concurrently measured MVBS. The high along-track resolution of egg counts provided by the Continuous Underway Fish Egg Sampler (CUFES) is a good match to the ADCP-based data. Large interannual differences in the pattern and density of sardine eggs are clearly related to the concurrently observed patterns of surface temperature and MVBS. The strong spatial relationship between sardine eggs and MVBS is particularly evident because of the large contrast in zooplankton biomass between the 1998 El Niño and 1999 La Niña. The inshore distribution of sardine spawning appears to be limited by the low temperatures of freshly upwelled waters, although the value of the limiting temperature varies between years. Often there is an abrupt offshore decrease in MVBS that is coincident with the offshore boundary of sardine eggs. Possible reasons for this association of sardine eggs and high zooplankton biomass include an evolved strategy that promotes improved opportunity of an adequate food supply for subsequent larval development, and/or adult nutrient requirements for serial spawning. Hence, the distribution of these parameters can be used as an aid for delineating the boundaries of sardine spawning habitat. [source] An integrated biogeochemical and economic analysis of bioenergy crops in the Midwestern United StatesGCB BIOENERGY, Issue 5 2010ATUL K. JAIN Abstract This study integrates a biophysical model with a county-specific economic analysis of breakeven prices of bioenergy crop production to assess the biophysical and economic potential of biofuel production in the Midwestern United States. The bioenergy crops considered in this study include a genotype of Miscanthus, Miscanthus×giganteus, and the Cave-in-Rock breed of switchgrass (Panicum virgatum). The estimated average peak biomass yield for miscanthus in the Midwestern states ranges between 7 and 48 metric tons dry matter per hectare per year ( t DM ha,1 yr,1), while that for switchgrass is between 10 and 16 t DM ha,1 yr,1. With the exception of Minnesota and Wisconsin, where miscanthus yields are likely to be low due to cold soil temperatures, the yield of miscanthus is on average more than two times higher than yield of switchgrass. We find that the breakeven price, which includes the cost of producing the crop and the opportunity cost of land, of producing miscanthus ranges from $53 t,1 DM in Missouri to $153 t,1 DM in Minnesota in the low-cost scenario. Corresponding costs for switchgrass are $88 t,1 DM in Missouri to $144 t,1 DM in Minnesota. In the high-cost scenario, the lowest cost for miscanthus is $85 t,1 DM and for switchgrass is $118 t,1 DM, both in Missouri. These two scenarios differ in their assumptions about ease of establishing the perennial crops, nutrient requirements and harvesting costs and losses. The differences in the breakeven prices across states and across crops are mainly driven by bioenergy and row crop yields per hectare. Our results suggest that while high yields per unit of land of bioenergy crops are critical for the competitiveness of bioenergy feedstocks, the yields of the row crops they seek to displace are also an important consideration. Even high yielding crops, such as miscanthus, are likely to be economically attractive only in some locations in the Midwest given the high yields of corn and soybean in the region. [source] The use of muscle protein for egg production in the Zebra Finch Taeniopygia guttataIBIS, Issue 2 2002Mat Cottam Pectoral muscle can be an important source of protein for birds. During egg formation Zebra Finches Taeniopygia guttata are able to compensate for nutritional inadequacies in their diet by utilization of the protein in their flight muscles. This analysis of flight muscle sarcoplasm supported earlier observations of protein depletion during egg production. However, SDS gel electrophoresis of the sarcoplasm produced no evidence to support a previous suggestion of the existence of a high molecular weight storage protein, and it is thought that the original observation may have arisen as an artefact of experimental methodology. During laying, protein removal from the sarcoplasm occurred over a range of different proteins and was not confined to any one specific protein band. Additionally, the protein band most reduced over the course of laying did not contain elevated levels of the amino acids most limiting to egg production. These results indicate that during laying, flight muscle sarcoplasm contributes towards the nutrient requirements of egg production from general protein reserves, rather than from a specific storage protein containing elevated levels of limiting amino acids. [source] Taught by animals: how understanding diet selection leads to better zoo dietsINTERNATIONAL ZOO YEARBOOK, Issue 1 2005B. D. Moore Wild animals invariably obtain their nutrient requirements, regulate their ingestion of toxins and even self-medicate. This review suggests that, while size and morphology dictate gross diet, the ability to select a diet is learnt. Animals learn to distinguish nutritious foods from less beneficial or toxic items through the positive and negative consequences of ingestion. In this process, early life experiences appear to be critically important. Zoo animals can rarely be provided with their wild diets and caretakers substitute nutrients from other sources. Thus, a suitable range of ingredients should be provided to give the animals a stimulating and nutritious diet that ensures excellent health. [source] Gene response elements, genetic polymorphisms and epigenetics influence the human dietary requirement for cholineIUBMB LIFE, Issue 6 2007Steven H. Zeisel Abstract Recent progress in the understanding of the human dietary requirement for choline highlights the importance of genetic variation and epigenetics in human nutrient requirements. Choline is a major dietary source of methyl-groups (one of choline's metabolites, betaine, participates in the methylation of homocysteine to form methionine); also choline is needed for the biosynthesis of cell membranes, bioactive phospholipids and the neurotransmitter acetylcholine. A recommended dietary intake for choline in humans was set in 1998, and a portion of the choline requirement can be met via endogenous de novo synthesis of phosphatidylcholine catalyzed by phosphatidylethanolamine N-methyltransferase (PEMT) in the liver. Though many foods contain choline, many humans do not get enough in their diets. When deprived of dietary choline, most adult men and postmenopausal women developed signs of organ dysfunction (fatty liver, liver or muscle cell damage, and reduces the capacity to handle a methionine load, resulting in elevated homocysteine). However, only a portion of premenopausal women developed such problems. The difference in requirement occurs because estrogen induces expression of the PEMT gene and allows premenopausal women to make more of their needed choline endogenously. In addition, there is significant variation in the dietary requirement for choline that can be explained by common polymorphisms in genes of choline and folate metabolism. Choline is critical during fetal development, when it alters DNA methylation and thereby influences neural precursor cell proliferation and apoptosis. This results in long term alterations in brain structure and function, specifically memory function. IUBMB Life, 59: 380 - 387, 2007 [source] Improving food purchasing choices through increased understanding of food labels, using itemized till receipts to measure these changesJOURNAL OF HUMAN NUTRITION & DIETETICS, Issue 4 2008P.M. Rigby Background:, Rising obesity and the associated risks of diabetes and heart disease require changes in diet to bring about healthier eating. To achieve this, people need to understand nutrition and daily requirements but are frequently confused by nutrition information on food labels. The introduction of the Food Standards Agency's ,Traffic Light' and the alternative ,Guideline Daily Amount' systems may help or further confuse the public. A previous study showed that although 63% of study participants read labels, only 25% claimed to understand them, also knowledge of nutrient requirements and functions was low (Rigby, 2004). Ransley et al., (2001) have shown that till receipts can be used to estimate fat and energy intake. The aim of the current study was to investigate whether an intervention designed to improve understanding of nutrition and labels could improve food purchases and whether these changes could be measured from till receipts. Method:, Participants were recruited from the general public (80 female; 23 males) (age <30 years (23), 31,45 years (25), 46,60 years (30), >60 years (22). Subjects were randomly assigned to either the intervention group (n = 78) who were provided with an information booklet and credit card sized nutrition and labelling information to use when shopping, or the control group (n = 25), who received the information after four weeks of normal shopping. The intervention group provided an initial till receipt pre intervention and was then given the nutrition and labelling material. Further till receipts were returned from successive shopping trips over the following 4 weeks. The nine categories of food used for comparison were: fruit and vegetables, saturated fats, monounsaturated fats, polyunsaturated fats, white cereals, wholegrain cereals, processed foods, full fat and reduced fat items. Ethics approval was obtained from NWW Wales NHS Trust ethics committee. Results:, Each of the nine food categories on till receipts were calculated as a percentage of the total shopping, excluding non-food items. General linear model repeated measures analyses showed differences between study participants' food purchases. For the intervention group, purchases in three of the nine food categories showed significant improvements: increased purchases of fruits and vegetables (P < 0.001); reduction in purchases of saturated fats (P < 0.001); and reduction of white cereal purchases (P < 0.050). The control group showed no differences in any category. Discussion:, Although the intervention group did show improvements in most of the other food categories, they were not statistically significant. Positive changes were found in seven of the nine categories, with only one, wholegrain cereals, showing a decrease in purchases rather than an increase. The control group displayed a random pattern over the four till receipts, with eight categories either showing negative change or no change; only one showed a positive change. The disproportionate group sizes may mean that it is not be possible to draw firm conclusions regarding the effectiveness of the intervention. Conclusions:, This study demonstrates that positive changes in improving food-purchasing choices, as measured by till receipts, can be made by using educational interventions. Further larger studies using routinely collected supermarket data would enable the study to be replicated on a much larger scale. References, Ransley, J.K., Donnelly, J.K., Khara, T.N., Botham, H., Arnott, H., Greenwood, D.C. & Cade, J.E. (1991) The use of supermarket till receipts to determine the fat and energy intake in a UK population. Public Health Nutr. 4, 1279,1286. Rigby, P. (2004) Effecting change. Understanding nutritional information. Can increased knowledge and understanding in relation to nutritional information bring about a change in eating habits? PhD Thesis WA: Bangor University. [source] What British children are eating and drinking at age 12,18 monthsJOURNAL OF HUMAN NUTRITION & DIETETICS, Issue 2 2000A. De La Hunty Background Health and growth during the first 2 years of life demand adequate nutrition. Proportionate to the toddler's size, the nutrient requirements exceed those of adults by up to six-fold. Objective This study reports the first national survey to assess the diets of British children at 14 months. Methods The data were gathered by postal questionnaire sent to the mothers who had participated in the 1995 National Survey of Infant Feeding. The results were evaluated in respect of the recommendations from COMA for the UK. Results A total of 5069 children of average age 14 months were included. Bread and cereal were consumed frequently. Fifty per cent of the children ate raw fruit, 51% ate cooked vegetables, 34% ate meat and 76% drank cow's milk daily. Consumption of sweetened drinks (such as squashes and carbonated drinks) was common. This study confirmed the influence of social, economic and educational inequalities on dietary practices. [source] When is an Individual an Individual Versus a Member of a Group?NUTRITION REVIEWS, Issue 5 2006An Issue in the Application of the Dietary Reference Intakes The Institute of Medicine (IOM) reports on Dietary Reference Intakes (DRIs) present a new paradigm for the description of nutrient requirements. Tradition and the DRI reports themselves have created an erroneous impression that the Recommended Dietary Allowance (RDA) is intended for use with individuals and the Estimated Average Requirement (EAR) is to be used with populations. Two recent IOM committee reports (one on nutrition labeling and one on Women, Infants and Children [WIC] food packages) challenge that interpretation, revealing the critical issues surrounding individuals versus groups or populations. The present paper examines the issues and concludes that the median requirement and Tolerable Upper Limit (UL) are the critical reference values for both individuals and populations. The RDA is both unneeded and lacking a sound scientific basis. [source] Meeting Requirements for Vitamin ANUTRITION REVIEWS, Issue 11 2000Clive E. West Ph.D., D.Sc. When the intake of foods or pharmaceutical preparations containing sufficient nutrients of adequate bioavailability are consumed, nutrient requirements are met and optimal nutritional status is maintained. Recent studies have shown that the basis for describing vitamin A activity of carotenoids overestimates the bioavailability of provitamin A carotenoids and their bioconversion to retinol (vitamin A). It is therefore proposed that instead of 6 pg from a mixed diet, 21 ,g ,-carotene are required to provide 1 ,g of retinol or 1 RE (retinol equivalent) of vitamin A. Based on this assumption and on data from food balance sheets, estimates of daily per capita vitamin A intake expressed in RE in Africa, South America, and Asia are reduced from 895, 599, and 667, respectively, to 371, 372, and 258, respectively. Such intakes are well below the recommended daily intake of 600 RE for adult males. A new combination of approaches will therefore have to be used to combat vitamin A deficiency rather than that used up until now. [source] Nutrient utilization and manure P excretion in growing pigs fed corn-barley-soybean based diets supplemented with microbial phytaseANIMAL SCIENCE JOURNAL, Issue 1 2009Adewale EMIOLA ABSTRACT The effect of high levels of microbial phytase supplementation in diets for growing pigs was studied in a 2-week performance and nutrient digestibility trial involving 28 growing pigs weighing 16.4 ± 1.06 (mean ± SD) kg. Seven corn-barley-soybean meal-based diets consisting of a positive control (PC) formulated to meet or exceed NRC nutrient requirements; a negative control (NC) with non-phytate P reduced by 0.1% unit from NRC requirement and fed without or with 500 or 1000 U/kg; a doubled negative control (DNC) with no added inorganic P and fed without or with 2000 or 4000 U/kg. Chromic oxide was added as an indigestible marker and all diets were fed as mash. Pigs fed the PC diet had a higher P digestibility compared with those fed the NC (P < 0.02) and the DNC (P < 0.001) diets. Supplementing the NC diet with pyhtase tended to improve P digestibility (P < 0.10). However, addition of phytase to the DNC diet resulted in linear (P < 0.001) and quadratic (P < 0.03) increases in P digestibility with an overall improvement of 8% and 121% at 4000 phytase U/kg of diet, respectively, compared with the PC and DNC diets. Apparent total tract digestibility of N, OM and DM were higher (P < 0.05) in the PC diet compared with the DNC diet, but not the NC diet (P < 0.10). No effect of phytase addition to NC was observed on Ca, N, DM and OM digestibility. Phytase addition to the DNC diet resulted in a linear increase (P < 0.05) in N, DM and OM digestibility but not Ca. Increasing the levels of phytase supplementation in the NC and the DNC diets linearly decreased fecal P (P < 0.05) content by 45 and 42%, respectively. Adding phytase at 1000 or 4000 U/kg increased P retention (P < 0.05) by 14.3 or 15.6% units, respectively, compared with the PC diet. Urinary P excretion was higher in the group fed the PC diet compared with those fed the NC and DNC diets (P < 0.05). The results of this study show that complete removal of inorganic P from growing pig diets coupled with phytase supplementation improves digestibility and retention of P and N, thus reducing manure P excretion without any negative effect on pig performance. [source] Lecithin requirements of juvenile Australian red claw crayfish Cherax quadricarinatusAQUACULTURE NUTRITION, Issue 4 2003K.R. Thompson Abstract Australian red claw crayfish Cherax quadricarinatus is considered a popular crustacean species in several countries around the world because of its large size potential and resemblance to high-priced American lobsters. However, little is currently known of the nutrient requirements and practical diet formulations for red claw. Lecithin has been shown to be required in the diets of several crustacean species, but there are no reports of dietary lecithin requirements for red claw. A 10-week feeding trial was conducted in an effort to evaluate lecithin requirements for juvenile red claw. Juvenile red claw (mean individual weight of 1.6 ± 0.91 g) were individually stocked in a recirculating system at random into 80 plastic-mesh culture units, each containing its own individual water line. There were 20 red claw per treatment (diet). Water was recirculated through biological and mechanical filters. Four semi-purified diets were formulated to contain increasing percentages of commercial soya bean lecithin (0, 0.5, 1.0 and 2.0%). Diet ingredients included solvent-extracted menhaden fish meal (FM), casein, dextrin, wheat flour, pellet binder, vitamin and mineral mix, cod liver oil, and corn oil. Semi-purified diets were formulated to contain 40% protein using casein, menhaden FM, and wheat flour as protein sources. After 10 weeks, no significant differences (P > 0.05) were found in final weight, percentage weight gain and specific growth rate with average values of 13.0 g, 934%, and 3.14% day,1, respectively. Percentage survival was high during the 10-week period (100, 95, 100 and 95%) as only two individuals died during the study; one of these, because of an escape from the culture unit. There was also no significant differences (P > 0.05) in percentage moisture, protein, fat and ash in whole-body red claw carcasses (wet-weight basis) among any treatment (diet) and averaged 77.1, 12.6, 1.3 and 6.2%, respectively. Based upon the present study, these results indicate that a diet containing 5% cod liver oil and 1% corn oil, and having no supplemental lecithin, may be sufficient for growth and survival of juvenile red claw crayfish. [source] | ||||||||||||||||