Dissertations / Theses on the topic 'Carbohydrate management'

A frequência ideal de pastejo em gramíneas tropicais é aquela associada com a interrupção da rebrotação quando o dossel forrageiro atinge 95% de interceptação da luz incidente (IL). Leguminosas forrageiras tropicais, particularmente o amendoim forrageiro, apresentam elevado potencial de uso, especialmente pela habilidade de fixar N2 atmosférico. Contudo, informações acerca de suas respostas sob condições de pastejo são escassas. O objetivo deste estudo foi avaliar as respostas agronômicas, as reservas orgânicas de C e N e a fixação biológica de N do amendoim forrageiro (Arachis pintoi cv. Belmonte) sob condições de pastejo. No caso das avaliações de fixação biológica de N, foram conduzidos dois experimentos, um sob lotação contínua e outro sob lotação intemitente (pastejo rotativo). Durante o período que antecedeu cada um dos experimentos (entre 60 e 90 dias) os piquetes foram submetidos aos tratamentos de pastejo para adaptação. Para o experimento de lotação intermitente os tratamentos corresponderam a combinações entre duas condições pré- (95% e máxima interceptação de luz durante a rebrotação - IL95% e ILMáx, respectivamente) e duas condições pós-pastejo (alturas pós-pastejo correspondentes a 40 e 60% da altura pré-pastejo) alocados às unidades experimentais segundo arranjo fatorial 2x2 e delineamento de blocos completos casualizados, com quatro repetições. Para o experimento de lotação contínua os tratamentos corresponderam a quatro alturas de manejo (5, 10, 15 e 20 cm) mantidas constantes ao longo de todo o período experimental. As avaliações foram realizadas ao longo de todo o ano, em épocas predeterminadas. Sob lotação intermitente, pastos manejados com a meta IL95% apresentaram menor altura pré-pastejo (13,3 cm) relativamente a pastos manejados com a meta ILMáx (18,5 cm), assim como menor acúmulo de estolão durante a rebrotação, porém sem diferença em acúmulo de forragem. Variações estacionais nas respostas agronômicas estiveram associadas ao ciclo anual de desenvolvimento das plantas e sua estratégia para otimizar recursos energéticos, evento conhecido como segmentação. Ao contrário da maioria dos relatos apresentados na literatura, pastejos frequentes (IL95%) e severos (40% da altura pré-pastejo) sob lotação intermitente ou mais intensos sob lotação contínua (alturas de manejo de 5 e 10 cm) não ocasionaram impactos negativos sobre o sistema radicular e o processo de nodulação. Contudo, maiores valores de nitrogênio oriundo da fixação biológica (%Ndda ) e a FBN (kg ha-1 N) foram obtidos em pastos manejados com estratégias de manejo de intensidade de pastejo moderada a leniente, caracterizadas por valores maiores de biomassa da parte aérea (IAF médio) independente do método de pastejo empregado. As reservas orgânicas de carbono (C) e nitrogênio (N) apresentaram variações ao longo do ano. De forma geral, períodos menos propícios ao crescimento e desenvolvimento da espécie (outono/inverno e início de primavera) apresentaram acúmulo de CHO\'s e nitrogênio solúvel tanto em concentração como em quantidade (pool). Independentemente do método de pastejo considerado, lotação contínua e lotação intermitente, as respostas avaliadas apresentaram como ponto comum a luz e suas relações, uma vez que quando avaliadas em função da biomassa áerea média ou IAF médios seguiram um mesmo continuum de variação. Intensidade de pastejo moderada a leniente parece ser a mais indicada para o manejo do amendoim forrageiro sob pastejo.<br>The ideal grazing frequency of tropical forage grasses is associated with the interruption of regrowth when sward canopy intercepts 95% of the incident light (LI). Tropical forage legumes, particularly forage peanut, have a high potential of use, specialy due to their ability to fix nitrogen from the atmosphere. However, information about their responses under grazing are scarse. The objective of this study was to evaluate the agromic responses, C and N organic reserves and nitrogen biological fixation (NBF) of forage peanut (Arachis pintoi cv. Belmonte) under grazing. For measurements regarding NBF, two experiments were carried out, one under continuous and other under intermitent stocking (rotational grazing). Prior to the beginning of the experiments (between 60 and 90 days), paddocks were subjected to the grazing treatments for adaptation purposes. For the intermitent stocking experiment, treatments corresponded to combinations between two pre- (95% and maximum canopy light interception during grazing - LI95% and LIMax, respectively) and two post-grazing conditions (post-grazing heights equivalent to 40 or 60% of the pre-grazing height). For the continuous stocking experiment, treatments corresponded to four grazing intensities represented for sward management heights of 5, 10, 15 and 20 cm. The experimental design was the same, a randomized complete block with four replications. Measurements were carried out throughout the year, in pre-determined seasons. Under intermitent stocking, swards managed with the LI95% target were shorter (13.3 cm) than those managed with the LIMax target (18.5 cm), and accumulated less stolon during regrowth, although with no difference in herbage accumulation. Seasonal variations in agronomic responses were associated with the annual cycle of plant development and strategy for optimizing energy use, an event known as segmentation. Contratry to the majority of reports in the literature, frequent (LI95%) and severe (post-grazing height equivalente to 40% of the pré-grazing height) grazings under intermitent stocking or intense grazing under continuous stocking (management heights of 5 and 10 cm) did not cause negative impacts on root mass and nodulation. However, greater values of nitrogen originated from biological fixation (%Ndda ) and NBF (kg ha-1 N) were recorded on swards managed with moderate to lenient grazing intensities, characterized by greater values of aerial biomass (average LAI) regardless of the grazing method used. C and N organic reserves varied throughout the year. In general, there was an accumulation of soluble carbohydrates and nitrogen (concentration and pool) during periods of limited availability of climatic growth factors (autumn/winter and early spring). Independent of grazing method, continuous or intermitent stocking, plant responses had their variability well associated with light and its relations, since when ploted against average aerial biomass or LAI followed the same continuum of variation. Moderate to lenient grazing intensity seems to be the most adequate for managing forage peanut under grazing.

Alfalfa (Medicago sativa L.) harvest schedules are often interrupted by rainfall, unfavorable environmental conditions for growth, and unfavorable weather for hay curing. Interruptions in alfalfa harvest schedules can delay the final harvest until dates considered critical to winter survival. Harvests made between 20 September and 30 October are considered detrimental to the persistence of alfalfa stands in geographical areas such as western Virginia. The objectives of this study were to determine if a critical period for fall harvest management actually exists in Virginia, if length of the growth period prior to fall harvest (GPPFH) influences plant persistence and succeeding spring yields, and if photosynthesis offsets respiration and allows more flexible fall harvest management than is currently recommended. Final alfalfa harvests were made 10, 20, or 30 September or 10, 20, or 30 October for 2 years in two identical experiments. Alfalfa was managed to achieve 30, 40, 50, or 60 days of growth prior to each fall harvest date. Total nonstructural carbohydrates (TNC) in tap roots and population of surviving plants were determined in December and March. Succeeding spring yields were measured in May. Zero, 45, and 60 percent shade were imposed following four fall harvest dates in a supplemental study to investigate the influence of photosynthesis on TNC levels and plant persistence. In the supplemental study, CO₂ exchange and TNC were measured at 2 week intervals in the fall following four fall harvest dates. Harvests made during the fall period previously considered as critical did not cause over-wintering plant losses. Length of growth period prior to fall harvests was more important than date of fall harvest in making management decisions for fall harvest. Although spring yield generally increased with length of GPPFH, the spring growth appeared healthy; so one might expect a few days of delay prior to the first spring harvest to eliminate any detrimental influence of short length of GPPFH. Succeeding spring yields and TNC levels were generally high for the 50-day GPPFH, and fall harvest yield offset any reductions in spring yield observed in this study. In addition, fall harvests made with a 50-day GPPFH maintained quality and leafiness as opposed to a 60-day GPPFH. Fall regrowth and plant maintenance were not dependent on root TNC accumulation. Photosynthesis offset TNC losses for regrowth and maintenance during the fall. High photosynthetic rates as compared to respiration occurred because temperatures were within the optimum range for photosynthesis of alfalfa during 68% of the daylight hours from September through November. There was no critical period for fall harvest management with the environmental conditions experienced during this study. A 50 or 60-day GPPFH prior to fall harvest was adequate for plant persistence and high succeeding spring yields.<br>Ph. D.

A Florida strain of sweet potato whitefly, Bemisia tabaci (Gennadius), was found to have an expanded range which includes several new food crops. To determine why, we examined how it processes plant nutrients. The amino acid and carbohydrate content of phloem sap of poinsettia and pumpkin and of honeydew produced by the Florida strain and a strain from Arizona feeding on both plants were analyzed. Poinsettia phloem sap contained 15 amino acids; 14 of these were in pumpkin phloem sap. Almost all the same amino acids were in the honeydews produced by the two strains on the two hosts. Approximately half of the amino acids found in the honeydew were at concentrations which were significantly lower than concentrations in the phloem sap. Honeydew from both hosts contain six additional amino acids. The major one was glutamine which may be used to expel nitrogen. Carbohydrates in phloem sap and honeydew were common transport sugars, like sucrose. Both honeydews contained trehalulose, a disaccharide not previously associated with insects. Both strains processed phloem sap and honeydew from both plants in the same manner, but the Florida strain produced significantly larger quantities of honeydew; it is therefore assumed to process more phloem sap. Since this strain has access to more phloem sap it also has access to more of the amino acids which are in short supply in the phloem sap of some plants allowing it to broaden its range.

Objectives: In this pilot study, our intention was to ascertain what formulation of a carbohydrate-derived fulvic acid (CHD-FA) topical applicator was optimal for patients to use during a larger study where the efficacy of fulvic acid (CHD-FA) in treating moderate acne vulgaris will be investigated. Methods: 15 individuals with inflammatory acne with an acne grade of III or lower were asked to volunteer for the study. They were split into 3 groups. Each group was asked to use a different formulation (a cream base, gel base and wet applicator formulation) each week. After each week, the individuals returned to fill out a questionnaire evaluating the formulation they used that week. They were also examined by the clinician for any possible side effects, and given the next formulation to use for the following week. The trial was 3 weeks long, and after using all 3 formulations the individuals were asked to fill out a final questionnaire evaluating all 3 formulations. The clinician was also asked to fill out a questionnaire giving his/her opinion on the formulations. Results: The results did not give conclusive evidence of one particular formulation being favored above all the others. All the formulations performed more or less equally as well. According to the final questionnaire, 6 out of the 15 individuals were most satisfied with the wet applicator, 4 out of 15 preferred the cream base and 5 out of 15 preferred the gel base. 5 out of 15 individuals were least satisfied with the wet applicator, 3 out of 15 with the cream base, and 7 out of 15 were least satisfied with the gel. While there was no conclusive indication for one particular formulation, there were some common complaints or observations by individuals about each formulation. Most individuals said the wet applicator had an initial burning sensation to the skin upon application, but it disappeared a few seconds after application. Many individuals said they felt the cream base was oily and made the skin appear oily after application. The gel base was said to smell the worst, along with the wet applicator, while the cream smelt the least. A few individuals complained that the gel left a residue on the skin. Conclusion: While the study did not give a clear indication of one particular formulation that was preferred by individuals, it did produce interesting results that can be used to make some of the formulations more favourable. In the main trial, further investigation will be done to optimize the formulation.<br>Dissertation (MSc)--University of Pretoria, 2010.<br>Pharmacology<br>unrestricted

Thesis (M.S.)--University of Wisconsin--Madison, 1985.<br>Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 145-155).

<p>As obesity has become one of the most prevalent metabolic diseases, and diabetes mellitus has become the seventh leading causes of death in the United States, alternative food/nutrition-based approaches to tackle obesity that are both efficacious and cost effective are in high demand. Since starch and its derived products are the principal dietary supply of glucose, strategies of using slowly digestible starch to achieve moderated glycemic response and prolonged glucose delivery, as well as to locationally digest starch into the ileum, have shown successful results such as moderation of insulinemia and reducing food intake in obese animals. An important regulator of appetite suppression is the neuroendocrine system of the gut-brain axis. Glucagon-like peptide-1 (GLP-1), oxyntomodulin (OXM), and peptide YY (PYY) are the main anorexigenic peptide products of the intestinal enterendocrine L-cells that regulate postprandial insulin levels as well as satiety signals. The stimulation of the enteroendocrine L-cells throughout the gastrointestinal tract through glucose, fatty acids and proteins has been extensively studied and confirmed. However, the stimulatory effect of complex dietary carbohydrates on L-cells is not described. In this dissertation, we investigated the <i>in vitro</i> intestinal cell chemosensation of L-cells to α-amylase starch digestion products, named maltooligosaccharides (MOS), and in the possible application of using slowly digestible starch delivery of MOS <i>in vivo</i>.</p> <p>In Chapter II of this dissertation, we reported a significantly higher stimulatory effect of MOS on GLP-1 and OXM secretion compared to glucose in mouse and human L-cells, respectively. Additionally, maltotriose enhanced the relative expression of the gastrointestinal peptide, cholecystokinin. Moreover, MOS exhibited protective effects on barrier function and monolayer integrity of intestinal epithelial cells. </p> <p>In Chapters III and IV, we performed a multiomics approach where transcriptomic analysis and global protein profiling of mouse L-cells treated with different types of MOS showed that the carbohydrates exhibit their effects through the induction of exocytosis of GLP-1- or OXM-containing vesicles and not through a positive regulation of the proglucagon gene expression. It is suggested that MOS induce higher secretion, but not higher synthesis, of the proglucagon gene products. In addition, maltotriose treatment downregulated the relative expression of the glucotoxicity marker, thioredoxin-interacting protein, and upregulated the relative expression of tight junction proteins supporting a role of MOS in barrier function integrity.</p> <p>Translating the <i>in vitro</i> findings into an <i>in vivo</i> application that is beneficial for human health required the use of controllable tool for the delivery of MOS throughout the small intestine for sensing by a higher number of L-cells. Slowly digestible starch (SDS), compared to rapidly digestible starch, provided such a tool. For this purpose, we used alginate-entrapped SDS microspheres that digest distally into the ileum to examine the role of SDS in the intervention and prevention of obesity in C57BL/6J diet-induced obese (DIO) and lean mice models.</p> <p>Results showed that 20% SDS in low-fat diets significantly improved weight loss and food intake reduction in DIO mice converted to low-fat diet for 12 weeks. Similarly, 15% SDS in high-fat diets showed significant reduction in body fat percent and significant increase in lean body mass as well as considerable reduction in weight gain rate and food intake in lean mice fed on 45% of calories high-fat diet. Immunohistochemistry of small intestine of mice in both the intervention and prevention studies revealed an even and thorough distribution of GLP-1 positive L-cells.</p> <p>Overall, this dissertation proposes several insights into L-cell sensation of dietary starch-degraded MOS delivered by the consumption of slowly digestible starch. MOS exhibit unique influences on L-cell sensitivity and gut hormone productivity. Future research investigating the mechanisms of intestinal sensing of MOS, as well as the development of bioactive carbohydrate structures that could preserve body weight and modulate glucose tolerance <i>in vivo</i> is needed to translate these findings into nutritional recommendations and food products beneficial for human health. The intricate role of dietary carbohydrates on gut physiological response, related to satiety and food intake could be a new approach for design of foods for health applications.</p>