Nutrient Dilution Research Articles

Feed Restriction on Productive Performance of Layer Chickens: A Review

Feed restriction is method of feeding where time, duration and amount of feed are limited, and it has an impact on whether a bird is capable of achieving the same productive performance as unrestricted birds. Feed restriction included of quantitative and qualitative restriction that is in quantitative to limiting the amount of feed daily given to the animals whereas a qualitative restriction is related to nutrient dilution in the diet. Different research results indicated that restriction of feed on layers production have controversial effect on feed intake, feed conversion efficiency, body weight gain, egg weight and quality. Overall, the potential of feed restriction programs as a management’s tool is important to increasing the egg production, egg quality, reduce maintenance requirements and improvement of feed efficiency in layers chickens. Also can be lead to economical saving in cost of feeding in layers chicken, thus may be usefulness for commercial layers chicks production farms. Keywords : feed restriction, Layers, performance, production DOI: 10.7176/JBAH/11-11-04 Publication date: June 30 th 2021

Photosynthetic Acclimation and Growth Responses to Elevated CO2 Associate with Leaf Nitrogen and Phosphorus Concentrations in Mulberry (Morus multicaulis Perr.)

Mulberry (Morus spp.) is a multipurpose tree that is worldwide planted because of its economic importance. This study was to investigate the likely consequences of anticipated future elevated CO2 (eCO2) on growth, physiology and nutrient uptake of nitrogen (N), phosphorus (P) and potassium (K) in two most widely cultivated mulberry (Morus multicaulis Perr.) varieties, QiangSang-1 and NongSang-14, in southwest China. A pot experiment was conducted in environmentally auto-controlled growth chambers under ambient CO2 (ACO2, 410/460 ppm, daytime/nighttime) and eCO2 (710/760 ppm). eCO2 significantly increased plant height, stem diameter, leaf numbers and biomass production, and decreased chlorophyll concentrations, net photosynthetic rate, stomatal conductance and transpiration rate of these two mulberry varieties. Under eCO2 leaf N and P, and root N, P and K concentrations in both mulberry varieties decreased, while plant total P and K uptake in both varieties were enhanced, and an increased total N uptake in NongSang-4, but not in QiangSang-1. Nutrient dilution and transpiration rate were the main factors driving the reduction of leaf N and P, whereas changes in plant N and P demand had substantial impacts on photosynthetic inhibition. Our results can provide effective nutrient management strategies for a sustainable mulberry production under global atmosphere CO2 rising scenarios.

Cultivar‐dependent increases in mycorrhizal nutrient acquisition by barley in response to elevated CO2

Societal Impact StatementModern agriculture is under pressure to meet yield targets while reducing reliance on finite resources to improve sustainability. Climate change represents an additional challenge—elevated atmospheric CO2 concentrations may increase plant growth and boost yield, but the nutritional value of crops grown at elevated CO2 is often reduced. Arbuscular mycorrhizal fungi (AMF) can improve plant nutrition, although how this symbiosis will be affected by climate change is unclear. Here, we demonstrate mycorrhizal contribution to nitrogen and phosphorus nutrition in barley under current and future CO2 concentrations. In one cultivar, AMF substantially increased phosphorus uptake at elevated CO2 and prevented phosphorus dilution, suggesting the symbiosis may become more important for crop nutrient uptake in the future.Summary Globally important cereals such as barley (Hordeum vulgare L.) often engage in symbiosis with arbuscular mycorrhizal fungi (AMF). The impact of elevated atmospheric CO2 on nutrient exchange between these symbionts remains unknown. In controlled environment experiments, we used isotope tracers (15N, 33P, 14C) to quantify nutrient fluxes between two barley cultivars (Moonshine and Riviera) and their associated AMF at ambient (440 ppm) and elevated (800 ppm) CO2. Elevated CO2 reduced shoot N concentration in Moonshine, and shoot N and P concentration in Riviera. Elevated CO2 substantially increased mycorrhizal 33P acquisition in Moonshine. Mycorrhizal contribution to P uptake in Moonshine may have prevented dilution of tissue P concentration at elevated CO2. In Riviera, AMF did not improve 33P acquisition. Both cultivars received 15N from their AMF symbionts, and this acquisition was not influenced by CO2 concentration, although Moonshine received more 15N than Riviera. Our results suggest that AMF may provide substantial contributions to barley nutrition at current and projected future CO2 concentrations. This is especially noteworthy for barley, which is generally considered to have low mycorrhizal receptivity. AMF may help alleviate or avoid nutrient dilution normally observed at elevated CO2. Variation between cultivars indicates that mycorrhizal contribution to cereal nutrition could be improved through selective breeding practices.

Impact of water content and dietary organic carbon richness on gut bacteria in the earthworm Lumbricus terrestris.

Many higher and lower animal gut ecosystems have complex resident microbial communities. In contrast, ingested soil is the primary source of the gut microbial diversity of earthworms, invertebrates of fundamental importance to the terrestrial biosphere. Earthworms also harbor a few endemic bacteria including Tenericutes-affiliated Candidatus Lumbricincola of unknown function. Gut microbes are subject to nutrient fluctuations due to dilution effects during gut passage, the nutrient richness of the anoxic gut, and dietary organic carbon, factors that could alter their activity/detection. This study's objective was to assess the potential impact of these factors on the occurrence and activity of ingested and endemic bacteria in gut content of Lumbricus terrestris. Fermentation product profiles of anoxic undiluted and diluted gut content treatments were similar, suggesting that experimental increase in water content and nutrient dilution had marginal impact on fermentation. However, 16S ribosomal Ribonucleic Acid (16S rRNA) sequence abundances indicated that stimulated bacterial taxa were not identical in undiluted and diluted treatments, with dominate potentially functionally redundant phylotypes being affiliated to the Firmicutes, Fusobacteria and Proteobacteria. Although the earthworm-associated Tenericutes were not stimulated in these treatments, the occurrence of three Tenericutes-affiliated phylotypes varied with the organic carbon richness of the earthworm diet, with two phylotypes being associated with high organic carbon richness. 16S rRNA sequence abundances indicated that other dominant gut taxa also varied with dietary organic carbon richness. These findings illustrate that functionally redundant ingested bacteria and earthworm-associated Tenericutes might be influenced by nutrient fluctuations in the gut and organic carbon richness of the earthworm diet.

Association between free sugar intake and nutrient dilution among Japanese children and adolescents: the 2016 National Health and Nutrition Survey, Japan.

The influence of free sugar intake on nutrient intake remains unclear in Japanese children and adolescents with relatively low free sugar intake. This cross-sectional study aimed to investigate the relationship between free sugar and selected nutrient intakes using data from the 2016 National Health and Nutrition Survey, Japan, based on the WHO recommendations (<5 % or <10 % of energy (%E)) for free sugar intake. A 1-d weighed dietary record was assessed in Japanese children and adolescents (aged 1-19 years; n 2919). Mean intakes for selected nutrients and food groups were compared according to free sugar intake categories (<2·5 %E, 2·5 to <5 %E, 5 to <10 %E and ≥10 %E) with adjustment for sex, age and weight status. Inverse associations were observed between intakes of free sugars and twenty-one of twenty-four micronutrients assessed, except for vitamins A and C and Ca. Significantly reduced intakes were identified for twenty-two and fourteen micronutrients in the ≥10 %E and 5 to <0 %E categories, respectively, compared with the lower categories. Mean micronutrient intakes at the <2·5 %E category did not differ from those at the 2·5 to <5 %E category. Free sugar intake had positive associations with intakes of sugars and jams, confectioneries, fruit and vegetable juices, and soft drinks and negative associations with intakes of pulses and nuts and vegetables. This study showed that nutrient dilution was associated with higher free sugar intake among Japanese children and adolescents. The findings suggest that the WHO recommendations might help prevent nutrient dilution in Japanese children and adolescents.

Effects of broiler genetic strain and dietary amino acid reduction on (part I) growth performance and internal organ development

Genetic selection in broilers has resulted in improved growth performance, meat yield, and feed conversion efficiency. However, consumers have become increasingly concerned about modern broiler welfare that is related to their rapid growth rate, which may be alleviated by nutrient dilution. This study was conducted to investigate the effects of dietary amino acid (AA) reduction on the growth performance and internal organ development of different genetic strains of broilers. A randomized completed block design with a factorial arrangement of 10 treatments (5 strains × 2 AA levels) was used. The 5 different strains of broilers were fed either a control diet, with digestible AA (lysine, total sulfur AA, and threonine) at the highest recommended levels for the 5 strains, or an AA-reduced diet, with the digestible AA being 20% lower than the control diet. Feed conversion ratio was increased by AA reduction in all 5 strains during day 0–14, 14–28, and 28–41 but was not affected from day 41–55. Body weight and feed intake responses to AA reduction varied in the different strains and ages of birds. Liver weight relative to BW on day 40, and weights of the duodenum and jejunum relative to BW on day 60 were increased by decreasing the dietary AA concentration. These results indicate that the birds had adjusted their organ growth and metabolism in response to increases in digestion, absorption, and utilization efficiency to accommodate a decrease in dietary AA content. Surprisingly, the cost of feed required to produce the same BW was decreased in 4 of 5 strains on both day 41 and 55, which was largely because of the lower price of the diets containing reduced AA levels and the later compensatory growth experienced by the birds fed AA-reduced diets. In the future, when dietary AA levels need to be adjusted to control growth rate and improve welfare status, the genetic strain, age of the birds, and targeted goals need to be taken into consideration.

Association between free sugars intake and nutrient dilution among Japanese adults: the 2016 National Health and Nutrition Survey, Japan.

The association between free sugars and nutrient intake is unclear in Japanese adults with relatively low free sugars intake. This cross-sectional study aimed to elucidate this relationship using data from the 2016 National Health and Nutrition Survey, Japan, and according to the current World Health Organization (WHO) guidelines for the prevention of nutrient dilution [< 5% or < 10% of energy (%E)]. Dietary intake of Japanese adults (aged ≥ 20years; n = 16,652) was assessed using a 1-day weighed dietary record. Mean intakes for selected nutrients and food groups were compared among categories of free sugars intake (i.e., < 2.5%E, 2.5 to < 5%E, 5 to < 10%E, and ≥ 10%E) by adjusting for sex, age, weight status, smoking status, habitual drinking, and occupation. Free sugars intake was inversely associated with the intake of 16 of 24 micronutrients investigated. Compared to its lower categories of free sugars intake, significant reductions in intake were identified for almost all micronutrients at ≥ 10%E, whereas ten micronutrients were reduced at 5 to < 10%E. The intake of dietary fibre, sodium, potassium, calcium, and iron was lower at < 2.5%E than at 2.5 to < 5%E and/or 5 to < 10%E. Free sugars intake was also positively associated with sugars and jams, confectionaries, fruit and vegetable juices, and soft drinks and inversely with pulses and nuts and vegetables. This study identified nutrient dilution among Japanese adults with higher free sugars intake and confirmed the significance of the WHO guidelines for preventing nutrient dilution in Japanese.

Nutrient dilution and climate cycles underlie declines in a dominant insect herbivore.

Evidence for global insect declines mounts, increasing our need to understand underlying mechanisms. We test the nutrient dilution (ND) hypothesis-the decreasing concentration of essential dietary minerals with increasing plant productivity-that particularly targets insect herbivores. Nutrient dilution can result from increased plant biomass due to climate or CO2 enrichment. Additionally, when considering long-term trends driven by climate, one must account for large-scale oscillations including El Niño Southern Oscillation (ENSO), North Atlantic Oscillation (NAO), and Pacific Decadal Oscillation (PDO). We combine long-term datasets of grasshopper abundance, climate, plant biomass, and end-of-season foliar elemental content to examine potential drivers of abundance cycles and trends of this dominant herbivore. Annual grasshopper abundances in 16- and 22-y time series from a Kansas prairie revealed both 5-y cycles and declines of 2.1-2.7%/y. Climate cycle indices of spring ENSO, summer NAO, and winter or spring PDO accounted for 40-54% of the variation in grasshopper abundance, mediated by effects of weather and host plants. Consistent with ND, grass biomass doubled and foliar concentrations of N, P, K, and Na-nutrients which limit grasshopper abundance-declined over the same period. The decline in plant nutrients accounted for 25% of the variation in grasshopper abundance over two decades. Thus a warming, wetter, more CO2-enriched world will likely contribute to declines in insect herbivores by depleting nutrients from their already nutrient-poor diet. Unlike other potential drivers of insect declines-habitat loss, light and chemical pollution-ND may be widespread in remaining natural areas.

Water-level fluctuations are key for phytoplankton taxonomic communities and functional groups in Poyang Lake

Abstract Biological species can be assembled into functional groups based on functional traits, which are keys to understanding the response of phytoplankton to environmental factors, such as the physical and chemical characteristics of aquatic systems. Here, we studied the taxonomic and functional communities of phytoplankton over three years in Poyang Lake and further examined the effect of water-level on these groups. Phytoplankton were generally dominated by diatoms across seasons, followed by cyanobacteria and green algae. Functional groups were mainly composed of organisms tolerant to fluctuating mixing intensities, such as group P, which was mainly composed of filamentous Aulacoseira granulata and showed a typical seasonal variation. Compared to the other physical and chemical variables of the lake, water-level showed a greater influence on seasonal variations in phytoplankton total biomass, taxonomic communities and functional groups. The influence of water-level on phytoplankton communities included two aspects: direct effects of biomass dilution and mixing and indirect effects of nutrient dilution and underwater light availability. Our results also indicated that the functional groups were more sensitive to water-level than the taxonomic communities, which was supported by the higher variation of functional groups explained solely by water-level. Collectively, these findings illustrate the direct and indirect effects of water-level on phytoplankton taxonomic communities and functional groups, and providing insights into how water-level can alter phytoplankton communities in a larger complex floodplain system.

Changes in phosphorus concentration in needles of adult Norway spruce - nutrient re-translocation or dilution effect?

Regarding the low availability of phosphorus in soil, tree internal cycling of phosphorus through re-translocation among needles would be a good strategy for conifers to cope with soil phosphorus deficiency and to support new needles in annual growth. Therefore, the relationship between the amount of plant-available phosphorus in the soil and the differences in concentrations of phosphorus among first- and second-year needles (P-difference Ny1 − Ny2) of adult Norway spruce was examined. No significant correlation could be detected between the stocks of available phosphorus extracted using citric acid and P-difference Ny1 − Ny2, even for trees with deficient nutritional status. The temporal variations of P-difference Ny1 − Ny2 at single plots showed the same order of magnitude as the variability between plots. The typically lower concentrations of phosphorus in second-year needles result mainly from an increase in needle weight of older needles. The net phosphorus re-translocation into younger needles appears to be of minor importance.

Dietary Energy and Amino Acid Enhancement From a Multi-enzyme Preparation

This study investigated the effect of Rovabio® Advance (Enz), containing high levels of endo-xylanase (Xyl) and arabinofuranosidase (Abf) activities, on energy and ileal amino acid (AA) digestibility of a complete wheat/soybean-based diet in broilers. The commercial control diet was compared with a 3% nutrient-diluted version using silica as inert diluent. Digestibility of dry matter, AA, and gross energy were determined by analysis of feed, excreta, and digesta. Ross PM3 broiler chicks were studied during the grower period, and diet dilution did not cause feed intake to increase. Fecal energy digestibility was similar (approximating 73%) for diets without Enz (P = 0.99). However, apparent metabolizable energy (AME) content was significantly lower in the diluted vs. control diet. Enz improved energy utilization (P < 0.001), leading to an increase of AME content of the diluted and standard diets. AME content of the diluted diet with Enz was similar to that of the standard diet without Enz (P = 0.98), demonstrating the ability of Enz to fully compensate the 3% nutrient dilution. At ileal level, AA digestibility was around 75% across all treatments. The addition of Enz increased AA digestibility by an average of 4.4% (P < 0.001).

Phytoplankton Productivity and Hydrology in an Impacted Estuarine Complex in Northeastern Brazil

The aim of the current study was to evaluate the productive capacity of the phytoplankton community and other environmental variables in the estuarine area of Suape; while considering the constant morphological, sedimentological and hydrological changes, the site has been facing due to the implementation and expansion of an industrial and port complex. The study comprised 6 campaigns: 3 in the dry season and 3 in the rainy season. Water samples were collected from the surface layer of the internal and external portions of the estuarine bay during low spring tides. The salinity ranged from 32.20 to 37.10, the water temperature ranged from 26.60°C to 29.40°C, and the oxygen saturation rate ranged from 58.5% to 114.5%. There was significant seasonal variation. The nitrite concentration was higher during the rainy season, whereas the ammonia concentration was higher during the dry season; the higher ammonia concentration helped increase chlorophyll-a levels and rates of primary productivity, which ranged from 0.02 - 2.45 mg·m−3 and from 0.34 to 4.32 mg·C·m−3·h−1, respectively. Chlorophyll-a < 20 μm was the fraction of biomass most commonly present in the estuarine ecosystem, accounting for 88.6% of the chlorophyll-a-containing biomass, and this reflected the low nutrient content in the water and indicated that the area was free from eutrophication processes. The decrease of rainfall during the sampling months and the anthropogenic changes in the environment led to reduced continental contributions, increased marine interference, nutrient dilution and loss of phytoplankton production capacity in Suape Bay, which severely damaged other trophic links in the ecosystem.

Genotypic Variation on Root Growth and Nutrient Uptake in Corn and Soybean

Core Ideas Drought‐tolerant corn increased root length up to 33% over conventional corn. Differences in root growth among soybean genotypes were site‐specific. Nutrient dilution effect occurred in both corn shoot and root, but not in soybean. N, P, Mn, and Zn concentrations were higher in the root biomass for soybean compared with corn. Larger root systems can help crops to explore more soil volume and increase nutrient uptake. The objective of this study was to evaluate potential differences in root system growth of two corn (Zea mays L.) and two soybean [Glycine max (L.) Merr.] plants of contrasting genotypes. Two experiments were conducted as part of this study (greenhouse and field). The corn genotypes used in the study were considered as drought tolerant (DT) and conventional (CR)–not drought tolerant; whereas soybean genotypes were considered as highly suitable for poorly drained soils (PD) and suitable for well‐drained soils (GD). During the growing season, shoots and roots biomass were recorded and analyzed for total nutrient concentration. Roots were scanned and processed to measure root length, surface area, diameter, and volume. In the greenhouse, corn root length and volume showed greater values for the DT at the VT growth stage compared with the CR. The DT also showed higher N, Mn, and Zn uptake. In the field, the DT showed greater root length at one location. For soybean, the GD showed increased root surface area and volume at one location when compared with the PD. The PD showed higher Zn uptake than the GD. Furthermore, evaluations of nutrient dilution as a function of root biomass was similar to those observed for shoot biomass for corn, but not clear for soybean. This study emphasizes the importance of root system evaluations among different genotypes as it can help on strategies to increase nutrient uptake by crops.

Effects of temperature increase and nutrient enrichment on phytoplankton functional groups in a Brazilian semi-arid reservoir

Abstract Aim Our study aimed to evaluate changes in the phytoplankton functional groups brought about by increases in temperature and nutrients predicted by the Intergovernmental Panel on Climate Change (IPCC) scenario for semi-arid regions. Methods Two experiments were performed, one in the rainy season and another in the dry season. The nutrient enrichment was based on the annual mean values (August 2012-August 2013) of soluble reactive phosphorus and nitrate verified in the reservoir. The microcosms were exposed to two different temperatures, the five-year average of air temperature in the reservoir (control) and 4°C above the control temperature (warming). The experiment was conducted over 12 days; every three days water samples of approximately 60 mL in volume were taken from the reservoir for chemical and phytoplankton analysis. All species were classified by Reynolds Functional Groups (RFG). Results The functional groups H1, X1, LO and S1 were the most representative in both seasons (rainy and dry). Our results showed that bloom-forming cyanobacteria, in particular the species of functional groups H1 and M, commonly reported in reservoirs in semi-arid regions of Brazil, were not significantly benefited by the warming and nutrient enrichment. The recruitment of other blue-green species, as well as diatoms and green algae, could be observed. Conclusions The effects of warming and/or nutritional enrichment can change the structure of the phytoplankton community. However, as not expected as the pessimist scenario, in our study the bloom-forming phytoplankton functional groups did not show changes in relative biomass. Instead, the recruitment of diatoms and green algae currently found in enriched environments was verified, specifically in the rainy period, when nutrient dilution typically occurs.

Nutrient Uptake and Utilization and Antioxidants of Fruits in Red Raspberry (Rubus idaeus L.) Cultivar ‘Autumn Bliss’ in response to Fertilization under Extended Photoperiod

Annual-fruiting cultivars of red raspberry (Rubus idaeus L.) complete its entire cycle of vegetative growth, flowering, and fruiting in one growing season, which has not been well studied in response to treatments of photoperiod and fertilization. In this study, micro-propagated plantlets of ‘Autumn Bliss’ were planted in a greenhouse at Dalian, Northeast China. Some were treated with fertilizers at the rate of 12 g per plant (N-P2O5-K2O, 14-14-14) under extended photoperiod of 17 h with PPFD of 240 μmol m-2 s-1 at dark-time (Pho.+Fert.), while others were treated with longer photoperiod (Pho.) or with the control. Compared to the control, both growth and biomass in shoot part of ‘Autumn Bliss’ were promoted by the Pho.+Fert. treatment, but foliar nutrients declined as the symptom of nutrient dilution. The Pho. treatment had no effect on either growth or nutrient uptake in leaves, resulting in the symptom of nutrient depletion compared to the Control. Soil P availability positively correlated with foliar P concentration but negatively correlated with root length. Only the Pho.+Fert. treatment resulted in the advance of fruiting by two months at July when fruits were measured to have acceptable fruit weight of about 3 g and contents of anthocyanin at ~26.4 mg cyaniding-3-glucoside equiv. 100 g-1 Fw and total phenolic content at ~17.5 mg GAE 100 g-1 Fw.

Carbon and nitrogen allocation shifts in plants and soils along aridity and fertility gradients in grasslands of China.

Plant carbon (C) and nitrogen (N) stoichiometry play an important role in the maintenance of ecosystem structure and function. To decipher the influence of changing environment on plant C and N stoichiometry at the subcontinental scale, we studied the shoot and root C and N stoichiometry in two widely distributed and dominant genera along a 2,200‐km climatic gradient in China's grasslands. Relationships between C and N concentrations and soil climatic variables factors were studied. In contrast to previous theory, plant C concentration and C:N ratios in both shoots and roots increased with increasing soil fertility and decreased with increasing aridity. Relative N allocation shifted from soils to plants and from roots to shoots with increasing aridity. Changes in the C:N ratio were associated with changes in N concentration. Dynamics of plant C concentration and C:N ratios were mainly caused by biomass reallocation and a nutrient dilution effect in the plant‐soil system. Our results suggest that the shifted allocation of C and N to different ecosystem compartments under a changing environment may change the overall use of these elements by the plant‐soil system.

Growth, biomass accumulation and foliar nutrient status in fragrant rosewood (Dalbergia odorifera T.C. Chen) seedlings cultured with conventional and exponential fertilizations under different photoperiod regimes

ABSTRACTIn this study, fragrant rosewood (Dalbergia odorifera T.C. Chen) seedlings were cultured with conventional and exponential fertilization treatments at rates of 2 and 4 g plant−1 (15–9–12), and an unfertilized control under the natural photoperiod and extended photoperiods with supplementary lighting for 3 and 6 h. Seedlings under the extended photoperiods had greater height but less root-collar diameter than those under the natural photoperiod. The extended photoperiod with supplementary lighting for 3 h resulted in the greatest biomass in stem and root. Apparent nutrient dilution was found from October 2015 to January 2016 in most fertilization treatments, which, however, was counted by the treatment of exponential fertilization at 4 g plant−1. Vector analysis indicated that the treatment of extended photoperiod with supplementary lighting for 3 h induced nutrition depletion for nitrogen (N) and phosphorus (P) relative to the natural photoperiod, while the exponential fertilization treatment induced luxury consumption for all elements of N, P and potassium (K) relative to the control. In conclusion, the extended photoperiod of supplementary lighting for 3 h was recommended for the culture of fragrant rosewood seedlings, and the exponential fertilization resulted in better nutritional status by counting nutrient dilution relative to the conventional fertilization.

Effects of Constant Nutrient Input and Dilution Rate of Nutrient in Plankton Community Ecosystem in Presence of Toxin

We present a complete parametric analysis of a nutrient–phytoplankton–zooplankton system influenced by toxin. In this paper, we have integrated Holling type II functional response in four-dimensional mathematical model. For this model, we investigate a qualitative analysis of the system in which studying the boundedness, existence and stability of non-negative equilibria. We perform different thresholds conditions to show the different dynamic behaviours of the system by using the model parameters. Our analysis leads to oscillatory behaviour of the system in which changing the dilution rate of nutrient and constant nutrient input. It is also observed that the fraction of the consumption of phytoplankton devoted to produce the inhibitor plays a key role to change the steady-state behaviour to oscillatory behaviour. Further, we see that higher values of toxin sensitivity of zooplankton concentration play a vital role to control this system. Finally, the numerical simulations to illustrate these analytical findings are presented.

تأثیر تراکم مواد مغذی و اسید آمینۀ ال- گلوتامین افزودنی بر عملکرد رشد، مورفولوژی روده کوچک و پاسخ ایمنی جوجههای گوشتی

این مطالعه به منظور بررسی اثر سطوح مختلف تراکم مواد مغذی و گلوتامین افزودنی بر عملکرد رشد، مورفولوژی ژژنوم و پاسخ‌های ایمنی جوجه‌های گوشتی در دورۀ آغازین (10-0 روزگی)، رشد (24-11 روزگی) و پایانی (42-25 روزگی) انجام گرفت. آزمایشی با 320 قطعه جوجه گوشتی نر سویه راس 308 در قالب یک طرح کاملا تصادفی با 8 تیمار، 4 تکرار و 10 قطعه جوجه در هر تکرار انجام شد. در این آزمایش از دو سطح تراکم مواد مغذی (توصیه راس و 5 درصد رقیق شده) و 4 سطح گلوتامین (0، 5/0، 1 و 5/1 درصد) در قالب طرح کاملا تصادفی به صورت فاکتوریل 2×4 استفاده شد. نتایج آزمایش نشان داد که در دورۀ رشد و پایانی، تراکم مواد مغذی توصیه شده و گلوتامین افزودنی در جیرۀ غذایی موجب بهبود ضریب تبدیل خوراک می‌شود. افزودن گلوتامین موجب افزایش وزن نسبی ژژنوم، کل روده کوچک، تیموس و بورس گردید. سطح تراکم مواد مغذی و گلوتامین بر ارتفاع ویلی و عمق کریپت ژژنوم تأثیر معنی‌داری داشت. در بررسی ایمنی هومورال، بیشترین تیتر آنتی‌بادی بر علیه SRBC اولیه و ثانویه در تیمار حاوی 5/1 درصد گلوتامین و کمترین آن در گروه شاهد (بدون گلوتامین افزودنی) مشاهده شد. با تزریق زیر جلدی فیتوهماگلوتینین- P مشخص شد که گلوتامین افزودنی موجب افزایش ضخامت پردۀ بین انگشتان پای پرندگان گردید. بطور کلی نتایج حاصل از این تحقیق نشان داد که با تنظیم جیره‌های ‌غذایی با تراکم مواد مغذی توصیه شده برای سویه راس و افزودن 5/0 درصد گلوتامین، عملکرد رشد بهبود می‌یابد و تغذیه جوجه‌ها با جیرۀ حاوی 1 درصد گلوتامین افزودنی و تراکم مواد مغذی توصیه شده پاسخ‌های ایمنی ارتقاء می‌یابد.

Added sugar intake that exceeds current recommendations is associated with nutrient dilution in older Australians

ObjectivesA nutrient dilution effect of diets high in added sugar has been reported in some older populations, but the evidence is inconsistent. The aim of this study was to investigate the association between added sugar intakes (according to recommended guidelines) and nutrient intake, food consumption, and body mass index (BMI). MethodsA cross-sectional analysis of data collected between 2007 and 2009 from participants of the Blue Mountains Eye study 4 was performed (n = 879). Dietary intake was assessed using a semiquantitative food frequency questionnaire. Added sugar content of foods was determined by applying a systematic step-wise method. BMI was calculated from measured weight and height. Food and nutrient intakes and BMI were assessed according to categories of percentage energy from added sugar (EAS% < 5%, EAS% = 5%–10%, and EAS% >10%) using analysis of covariance for multivariate analysis. ResultsMicronutrient intake including retinol equivalents, vitamins B6, B12, C, E, and D, and minerals including calcium, iron, and magnesium showed a significant inverse association with EAS% intakes (Ptrend < 0.05). In people with the lowest intake of added sugars (<5% energy) intake of alcohol, fruits, and vegetables were higher and intake of sugar sweetened beverages was lower compared to other participants (all Ptrend < 0.001). BMI was similar between the three EAS% categories. ConclusionsEnergy intake from added sugar greater than the recommended level of 10% is associated with lower micronutrient intakes, indicating micronutrient dilution. Conversely, added sugar intakes <5% of energy intake are associated with higher micronutrient intakes. This information may inform dietary messages targeted at optimizing diet quality in older adults.