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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
221

Diferentes níveis vitamínicos na dieta de frangos de corte / Different vitamin levels in the diet of broilers

Monique Matias Mota 23 November 2012 (has links)
Foi realizado um experimento no aviário experimental do Departamento de Zootecnia da Universidade de São Paulo (USP), na Faculdade de Zootecnia e Engenharia de Alimentos (FZEA), em Pirassununga/SP com o objetivo de avaliar o efeito de dois níveis vitamínicos (comercial e OVN) com ou sem aflatoxina em dietas de frangos de corte no período de 1 a 42 dias. Foram utilizados 1800 pintinhos, machos, Cobb 500, distribuídos em um delineamento inteiramente casualizado em esquema fatorial 2 x 2 x 2 (2 níveis vitamínicos - comercial e OVN, 2 níveis de aflatoxina - 0 ppm e 0,5 ppm, e 2 níveis de adsorventes - 0 e 10 kg/ton), totalizando 8 tratamentos com 15 repetições de 15 aves cada. As dietas foram fornecidas fareladas e a base de milho e farelo de soja, formuladas segundo os níveis praticados por uma integradora da região. Para avaliar o desempenho foram analisados o consumo de ração, ganho de peso e conversão alimentar de 1 a 49 dias. Para avaliação de carcaça (rendimento de carcaça, peito e pernas), determinação de incidência de BBS e determinação do peso das vísceras abdominais e coração foram abatidas duas aves por repetição aos 45 dias. Os resultados mostraram que frangos de corte, machos, alimentados com nível OVN de vitaminas, apresentaram melhor ganho de peso, conversão alimentar, rendimento de carcaça e peito quando comparado com o nível comercial de vitaminas (P<0,05) e que as dietas contendo 0,5 ppm de aflatoxinas resultaram em menor ganho de peso, rendimento de carcaça, porcentagem de peito e aumentou o tamanho do coração e fígado do animal (P<0,05). O uso de 10kg/ton de adsorvente só apresentou resultado positivo no final da vida dos animais (dos 39 a 49 dias) (P<0,05) e somente na conversão alimentar. Esse estudo permite concluir que a aflatoxina resulta em perdas de desempenho e rendimento de carcaças e que o fornecimento de níveis ótimos de vitaminas melhora os resultados dessas características. O uso de adsorventes se mostrou inviável nesse estudo. / An experiment was conducted in an experimental aviary the Department of Animal Science, University of São Paulo (USP), the Faculty of Animal Science and Food Engineering (FZEA) in Pirassununga/SP, to evaluate the performance, carcass characteristics and weight of offal in broiler chickens fed with two levels of vitamins (commercial and VNO) with or without aflatoxin in broiler diets. Were used 1800 chicks, male, Cobb 500 distributed in a completely randomized 2 x 2 x 2 factorial arrangement (two vitamin levels, two levels of aflatoxin and two levels of adsorbents), totaling eight treatments with 15 replicates of 15 birds each. Diets were fed mash and corn and soybean meal, formulated according to the levels charged by an integrator in the region. To evaluate the performance were analyzed feed intake, weight gain, feed conversion from 1 to 49 days. For evaluation of carcass yield (carcass, breast and legs), determination of the incidence of BBS and determination of the weight of the abdominal viscera and heart were killed two birds per replicate at 45 days. The results showed that broilers, males fed VNO level of vitamins showed better weight gain, feed conversion, carcass yield and breast when compared to the commercial level of vitamins (P<0.05) and that diets intoxicated with 0.5 ppm of aflatoxin resulted in less weight gain, carcass yield, percentage of breast and increased the size of the heart and liver of the animal (P<0.05). The use of adsorbent 10kg/ton only had a positive result at the end of life of animals (from 39 to 49 days) (P<0.05) and only in the feed. This study indicates that aflatoxin results in loss of performance and carcass yield and the provision of optimal levels of vitamins improved the results of these characteristics. The use of adsorbents in this study proved to be unfeasible.
222

Aspectos da reatividade de vitaminas do complexo B frente ao estado tripleto excitado de flavinas / Aspects of the reactivity of B vitamins towards flavins triplet excited state

Leandro de Oliveira Rodrigues Arrivetti 14 September 2012 (has links)
Dentre os diversos fatores responsáveis pela instabilidade química das vitaminas nos alimentos, a exposição à radiação luminosa é determinante, principalmente em alimentos contendo vitamina B2. O presente trabalho investigou a degradação fotossensibilizada das vitaminas do complexo B (ácido fólico, piridoxal, biotina e niacina) por flavinas. O piridoxal-5\'-fosfato (PLP) mostrou-se reativo frente aos estados singleto e tripleto excitado das flavinas com constante de desativação de 1,03 1011 L mol-1 s-1 para o estado singleto, valor este superior ao valor esperado para reações bimoleculares controladas por difusão em meio aquoso. Foi observada uma dependência significativa da constante de velocidade de desativação do estado singleto excitado com a temperatura, onde o aumento da temperatura proporciona um decréscimo da constante de velocidade sugerindo a existência de um complexo [FMN...PLP] no estado fundamental o qual foi confirmado por espectroscopia de fluorescência resolvida no tempo. O PLP mostrou-se reativo frente ao estado tripleto excitado da FMN com constante de velocidade de 3kq = 3,0 108 L mol-1 s-1 em meio de tampão fosfato pH 6,4 ou em meio de óxido de deutério a 25 °C. Não foi observada diferença significativa entre as constantes de desativação do estado tripleto excitado em meio aquoso e de óxido de deutério o que corrobora com um processo direto de transferência de elétrons do PLP para a 3FMN* ao invés de um processo de transferência de átomo de hidrogênio. As vitaminas (biotina e niacina) mostraram-se não reativas frente aos estados singleto e tripleto excitados da vitamina B2 o que pode ser atribuído aos altos potenciais de oxidação, Eo > 2 V vs. NHE, observados para estas vitaminas em meio aquoso. A voltametria cíclica do PLP apresentou um processo anódico e irreversível (E= 1,07 V vs. NHE), controlada cineticamente por transferência de elétrons heterogênea do PLP para o eletrodo. O rendimento quântico de fotodegradação do PLP em meio aquoso e aerado é 2,5 vezes superior ao encontrado para a reação em meio anaeróbico, o que sugere a participação do íon superóxido no processo global de degradação do PLP. O ácido fólico demonstrou-se igualmente reativo frente ao estado tripleto excitado das flavinas (3kq= 4,8 108 L·mol-1 s-1 e Φ = 0,26 (meio aerado) e Φ = 0,32 (meio anaeróbico)) e a sua complexação pela β-LG (Φ = 0,032 (meio aerado) e Φ = 0,055 (meio anaeróbico)) uma eficiente abordagem na proteção desta vitamina frente a fotodegradação sensibilizada por flavinas. / Among several factors responsible for the chemical instability of vitamins in food, exposure to light radiation is decisive, especially in supplemented or fortified food with vitamin B2. This study investigated the photosensitized degradation of B-vitamins (folic acid, pyridoxal, biotin and niacin) by flavins. The pyridoxal-5\'-phosphate (PLP) reacted with singlet and triplet excited states of flavins with rate constant for quenching of 1kq = 1,03 1011 L mol-1 s-1 for the singlet state, this value is higher than expected value of bimolecular reactions controlled by diffusion in an aqueous solvent. A significant dependence was observed for the rate constant for deactivation of singlet excited state with temperature, the increase of the temperature leads to a decrease of the rate constant suggesting the existence of a complex [FMN...PLP] in ground state confirmed by time resolved fluorescence spectroscopy. PLP reacted with FMN triplet excited state with rate constant 3kq = 2,96 108 L mol-1 s-1 in phosphate buffer pH 6,4 or deuterium oxide at 25 °C. There was no significant difference between the rate constant of deactivation of the triplet-excited of FMN in aqueous solution or deuterium oxide which confirms a direct process of electron transfer to PLP for 3FMN* rather than a process of transfer of hydrogen atom. Biotin and niacin unreacted with singlet and triplet excited states of vitamin B2 which can be attributed to high oxidation potentials, Eo > 2 V vs. NHE, observed for this vitamins in aqueous solution. The cyclic voltammetry of PLP had an irreversible anodic oxidation process (E = 1.07 V vs. NHE) kinetically controlled by heterogeneous electron transfer from PLP to the electrode. The quantum yield of photodegradation of PLP in aerobic condition is 2.5 times higher than that found for the reaction in anaerobic condition, which suggests the of participation of superoxide ion in the PLP global degradation process. Folic acid demonstrated reactive with triplet excited state of flavins (3kq= 4,8 108 L·mol-1 s-1 and Φ = 0,26 (aerobic condition) and Φ = 0,32 (anaerobic condition)) and the complexation with β-LG (Φ = 0,032 (aerobic condition) and Φ = 0,055 anaerobic condition)) an efficient approach in protecting the vitamin against photodegradation sensitized by flavins.
223

Estudo da estabilidade de nectar de manga (Mangifera indica L.) envasado em garrafas pet, comparados com envasados em embalagem cartonada e lata de aluminio / Study of the stability of nectar of sleeve (Mangifera indicates L.) planted in bottles pet, compared with planted in cartonada packing and can of aluminio

Arruda, Ana Flavia Pedroso de 16 December 2003 (has links)
Orientador: Roberto Herminio Moretti / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos / Made available in DSpace on 2018-08-03T18:03:59Z (GMT). No. of bitstreams: 1 Arruda_AnaFlaviaPedrosode_M.pdf: 5724087 bytes, checksum: 5f150b453b4e7cefbf71614d42b7f60e (MD5) Previous issue date: 2003 / Resumo: No presente trabalho, foi estudada a viabilidade do uso da garrafa PET termorresistente como embalagem para néctar de manga, através de ensaios de vida de prateleira comparativos com embalagem cartonada Tetra Brik Aseptic e lata de alumínio comercializadas atualmente, durante um período de 180 dias, com armazenamento sob temperatura ambiente. Néctar de manga comercializado em embalagem cartonada Tetra Brik Aseptic foi adicionado de ácido ascórbico e goma xantana e processado em um sistema composto por um tanque de alimentação com capacidade de 8l, dotado de pressurizador manual para transporte do fluido, e serpentina imersa em banho de água quente, para envase manual realizado à quente (75 OC) em garrafas PET termorresistentes, que foram fechadas e invertidas, e assim mantidas por 2 minutos, antes do resfriamento em água fria. Foi adotado o Planejamento Experimental Completo tipo 22 cujas variáveis independentes foram a concentração do ácido ascórbico (com adições de 14,75 à 85,25 mg/100ml) e goma xantana (com adições de 0,012 à 0,068%), com a finalidade de retardar a oxidação e obter uma viscosidade aceitável pelo consumidor. As análises foram efetuadas com uma freqüência de 45 dias (1 Q, 45Q, 90Q, 135Q e 180Q dia após o processamento). As respostas analisadas foram: ºBrix, acidez titulável, pH, viscosidade, b-carotenos, análises microbiológicas (contagem de bolores/leveduras, contagem total, termófilos e coliformes fecais), determinações do teor de Vitamina C e de Cor e avaliação sensorial. As análises de variância dos resultados indicaram que as condições de processo reais estudadas não influenciaram as características físico-químicas do néctar (ºBrix, acidez titulável, pH e viscosidade). Sob o aspecto microbiológico, foi verificada a eficiência do processo de pasteurização. Durante o período de armazenamento avaliado (180 dias), foi verificado que o produto com teores maiores que 50,0 mg/100mL de ácido ascórbico e teores intermediários de goma xantana (0,04%) resultou em maior aceitabilidade. Sensorialmente, os produtos apresentaram médias de aceitação próximas ou superiores a 7,0, para o atributo de aceitação global, situado na escala hedônica não estruturada, equivalente a "gostei muito" e "gostei moderadamente". Em relação à resposta de cor, até 90 dias, houve redução da Luminosidade (L) para todas as amostras e todos os tratamentos dos produtos em PET ficaram com valores de L próximos aos dos produtos em Tetra Brik Aseptic e lata, e depois deste período a L aumentou para estes produtos e manteve-se relativamente estável nos experimentos com garrafas de PET. Para a cromaticidade (a e b) o produto na lata de alumínio apresentou-se mais escuro, quando comparado com os demais, enquanto as amostras em PET contendo maiores teores de ácido ascórbico adicionados apresentaram menor escurecimento no decorrer do período analisado / Abstract: In this work the viability of using thermoresistant PET bottles as package for mango nectar was studied. Three types of packages were studied: aluminum cans, multifoil package (Tetra Brik Aseptic) and PET bottles, by following the shelf-life of the mango nectar, for 180 days shelf-life period, under room temperature. Commercial mango nectar in multifoil package was used for the experiment. There was added ascorbic acid and xantham gum according to the Experimental Design (Surface Response). Product was thermal treated by heating at 75OC and filled at this temperature in PET bottles, closed and kept for two minutes, before cooling at room temperature. It was used the Complete Experimental Design 22, varying the ascorbic acid (14,75 mg/100mL up to 85,25 mg/100mL) and xantham gum (0,012% up to 0,068%), with the objective of reduce oxidation and get a better viscosity. Determination of: ºBrix, pH, titrable acidity, viscosity, b-carotenes, ascorbic acid, color, sensory evaluation and microbial analysis (molds and yeasts, total count, themophylos and coliforms) were done with a frequency of 45 days (1 Q, 45Q, 90Q, 135Q e 180Q day after bottling). Analysis of Variance showed that the process condition did not influence significantly the nectar physico-chemical characteristics (ºBrix, pH, titrable acidity and viscosity). Under the microbiological aspect, it was concluded the efficiency of the pasteurization process. Under the studied shelf-life period of 180 days, it was observed that mango nectar with higher concentrations of ascorbic acid (over 50mg/1OOmL) and intermediary concentrations (0,04%) of xantham gum, resulted in better acceptability. Organoleptically the products were accepted with scores of 7 or higher, for the attribute "global acceptance", in the non-structured hedonic scale, equivalent to "accept very much". In relation to the color attribute up to 90 days, Luminosity (L) for all samples in all experiments of PET packaged nectar, the L values were very close to the products in multifoil package and Aluminum can, after 90 days L increased for all products and was kept stable when packed in PET. For the chromaticity a and b the canned product in aluminum can presented darker products, when compared to the other experiments. Experiments in PET bottled nectar with higher ascorbic acid content resulted clearer products than the ones with lower addition of ascorbic acid, during the shelf-life period / Mestrado / Tecnologia de Alimentos / Mestre em Tecnologia de Alimentos
224

Determination of levels of vitamin D and its metabolites after feeding of high levels of vitamin D₃ to beef animals to alleviate the effects of beta-agonist supplementation in feedlot cattle

Moloto, Kgantjie Walter 05 November 2012 (has links)
M.Sc. / Various researchers have found that supplementing extremely high levels of dietary vitamin D₃ for a limited time prior to slaughter improved meat tenderness due to the increase in blood calcium levels caused by vitamin D, which play an important role in activating the calpain protease system. Vitamin D₃ is metabolised in the liver into 25-hydroxyvitamin D₃ , which controls calcium and phosphate homeostasis, a process regulated by parathyroid hormone. It is hypothesised that ultra-high vitamin D₃ supplementation should alleviate negative effects of beta-agonist supplementation (which reduces meat tenderness), but these levels might be toxic for human consumption. The aim of this study was to determine the levels of vitamin D₃ and its metabolites after feeding of high levels of vitamin D₃ to beef animals to alleviate the effects of beta-agonist supplementation in feedlot cattle and to determine the safety of tissues after ultra-high levels of supplementation of vitamin D₃ . In this study, 20 young steers received neither beta agonist nor vitamin D₃ (control, C), 20 animals each received zilpaterol hydrochloride (Z) and vitamin D₃ . Various levels of vitamin D₃ was administered (xM=x million units), for a given number (y) of days (yD) in some cases withdrawn (N) for a period of z days prior to slaughter (zN). Thus the following treatment groups were examined in this study: C, Z, Z3D7M, Z6D7M, Z6D7M7N and Z9D1M. Samples of liver, meat and fat were analysed for vitamin D₃ and 25-hydroxyvitamin D₃ . An HPLC method for quantification of vitamin D₃ and its metabolites was developed and used to quantify and compare vitamin D₃ and its metabolites from liver, meat and fat. Blood serum was analysed for calcium, phosphorus and parathyroid hormone. Serum calcium concentrations were analyzed using a colorimetric assay kit whereas plasma parathyroid hormone levels (PTH) were determined by an electrochemiluminescence immunoassay employing a sandwich test principle. Levels of vitamin D₃ and 25- hydroxyvitamin D₃ differed with the amount fed - levels in the meat were generally lower than the RDA. Vitamin D₃ was most abundant in liver, especially in the group supplemented with 7 million IU of vitamin D₃ for six days (Z6D7M), accumulating at an average level of 74 μg/100 g, followed by fat (8.39 μg/100 g accumulated vitamin D₃ ), which is higher than the average RDA. Vitamin D₃ supplementation resulted in significant lowering of the M. longissimus lumborum Warner-Bratzler shear force (WBS) and myofibril fragmentation (MFL). There were several positive and negative ix correlations between levels of 25-hydroxyvitamin D₃ and calcium, phosphate, parathyroid hormone and vitamin D₃ , WBS and MFL of M. longissimus lumborum and the muscle proteolytic degradation system (calpastatin, μ-calpain and mcalpain). Controversy remains regarding the upper limit (toxic level) of vitamin D₃ for human consumption. New studies indicate that the current RDA of vitamin D is too low for sufficient health benefits. Vitamin D₃ levels measured in this study were higher than the current RDA, but within the limit proposed by recent clinical studies. Vitamin D₃ as a tool for a meat tenderizer seems not providing reliable results because in this study the control group exhibited lower shear force than the treated groups who received vitamin D₃ zilpaterol supplementation. This is an indication that the tenderazation mechanism by vitamin D₃ still needs further elucidation before vitamin D₃ supplementation can confidently be used as a tool for meat tenderization.
225

Dietary Nutrient Intake and Cytokines in Children with Asthma and Allergic Disease

Sullivan, Allison January 2019 (has links)
No description available.
226

Farm to Pharmacy: Nutrition, Animals, and Governance in Britain 1870-1945

Igra, Alma January 2020 (has links)
This dissertation examines the emergence of nutrition science in the 20th century and the first cohort of experts who practiced nutrition as a form of medical diplomacy. Unpacking pivotal case studies in Scotland, Iraq, Vienna, Geneva, and Oxford, the project shows how scientific knowledge was produced on a local scale. I argue that knowledge about food developed in Britain from the late 19th century to World War II in a contingent path that involved much more than “discoveries” in labs. It was the unique formation of this discipline across national, international, and imperial political spheres that produced scientific standards and methods. Nutrition enabled a powerful language of exchange, metamorphosis, and commensurability that were vital for British political world systems. My research, therefore, investigates nutrition not just as medical innovation, but as a revolution in ecology and politics: food science was a way to reimagine the earth and Britain’s place within it. Scientific nutrition began as a marginal sub-field of agricultural science and came to acquire a central place in the definition of human needs. I show how critical terms of human nutrition – productivity, growth, and vitality – emerged from the attempt to improve animal health and from imperial agricultural planning. Even when the science of food moved from farms to pharmacies, through standardized units and products like vitamin supplements, animals and non-human factors continued to shape nutritional concepts, standards, and policies.
227

Vitamin - Fluoride supplements: effect on dental caries and fluorosis in sub-optimum fluoride areas

Hennon, David Kent, 1933- January 1975 (has links)
Indiana University-Purdue University Indianapolis (IUPUI) / This study was designed to determine if additional fluoride, ingested as a sodium fluoride - vitamin supplement would provide added protection against dental caries without causing any significant fluorosis. A total of 456 children, one to 14 months of age, residing in cities having 0.6 - 0. 8 ppm F in the water supply were randomly assigned according to age, sex and community to the following groups : Group A, 0. 5 mg F to age 3 then 1. 0 mg thereafter; Group B (control), vitamins throughout the study; and Group C, 0.5 mg F throughout the study. Dental examinations were started at approximately 2 1/2 to 3 years of age and were repeated every six months. A fluorosis examination ended the study after about seven years. When compared according to length of time on product, Group A had a significant reduction in deft and defs of 42.2 and 47.1 percent at 60 months. Group C had a 32.1 and 37.4 percent reduction. When compared by age, Group A had a 37.5 and 44.8 percent reduction in deft and defs at 66 months. Group C had a 34.3 and 40.1 percent reduction for the same period. No significant reductions were observed in permanent teeth. Based on the fluorosis index (Group A - 0.250; Group B - 0.033; and Group C - 0.188) none of the groups had any unacceptable amounts of fluorosis. The results indicate that up to 1.0 mg per day of additional fluoride does not cause objectionable fluorosis and may be ingested safely by children residing in areas containing 0. 6 - 0. 8 ppm F in the water supply. A 0.5 mg F supplement was almost as effective as a 1.0 mg level in providing added protection against dental caries in primary teeth.
228

Optimal Growth Conditions for Tracheal Epithelial Stem Cells

Amarachintha, Surya P. 21 August 2007 (has links)
No description available.
229

Riboflavin Metabolism of College Women on Self-Selected Diets

Harris, Jimmie Nell 08 1900 (has links)
The purpose of this study was to determine the riboflavin intake in food and the excretion in the urine and feces of young college women living in the home management house and eating a self selected diet from a common food supply.
230

An incidence study of vitamin and mineral supplementation among infants in Southwest Virginia

Favret, Jenny C. January 1986 (has links)
A longitudinal feeding study of 154 infants in Southwest Virginia was conducted during 1978-1980. The incidence of vitamin and mineral supplementation among these infants was the focus of the retrospective study discussed here. With the use of the Nutritional Analysis System of Louisiana State University, nutrient adequacy levels were determined. Vitamin D, vitamin E, folacin, vitamin B-6, and iron were the problem nutrients identified through this analysis. Inappropriate infant feeding practices such as the use of low iron formulas, the use of cow's milk, and the consumption of inadequate milk volume were blamed for these dietary deficiencies. Routine vitamin supplementation was common among infants of all feeding types. While much of the supplementation was unnecessary, large percentages of infants demonstrated a need for it. The exception was vitamin A. None of the infants who received supplemental vitamin A had inadequate dietary intakes of this nutrient. Supplementation was not shown to have an effect on weight or length gain measurements. Parents should be given specific infant feeding instructions prior to hospital discharge. Included should be a list of the circumstances which would indicate the need for supplementation. / M.S.

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