A região de Ribeirão Preto destaca-se no cenário nacional devido a suas atividades agrícolas, principalmente àquelas voltadas ao cultivo da cana-de-açúcar. Há, também, grande potencial hídrico na região: o Aquífero Guarani, sendo que a cidade de Ribeirão Preto é 100 % abastecida pelas águas desse reservatório. Em vista deste fato, foi estudada a mobilidade e biodisponibilidade de Pb e Cd na camada superior dos solos de Ribeirão Preto, em particular, na região de recarga e/ou afloramento do Aquífero Guarani e, em áreas de aterros sanitários em funcionamento ou desativados. Neste presente estudo, foram investigadas: (1) a concentração de Pb e Cd na camada superior do solo; (2) a retenção e potencial mobilidade de Pb e Cd usando procedimentos de extração simples e sequenciais; (3) a capacidade de adsorção estimada. Todas as medidas foram realizadas por espectrometria de absorção atômica com chama (F AAS) e atomização eletrotérmica (ET AAS). Para o procedimento de digestão ácida foi empregado o método USEPA 3050B. O procedimento de extração sequencial, protocolo BCR, foi utilizado nos estudos de distribuição dos analitos nos solos, bem como sua mobilidade. Empregou-se também o protocolo BCR modificado para solos tropicais para posterior comparação. Na avaliação de biodisponibilidade utilizou EDTA como agente extrator. Para os ensaios de adsorção em lote, o tempo de agitação foi otimizado em 2 horas. Foram aplicadas as equações para as isotermas linear, Langmuir e Freundlich. Não houve dificuldade para a determinação de chumbo, cujas concentrações encontravam-se dentro da curva de calibração e acima do limite de quantificação (LOQ), conforme figuras de mérito apresentadas para os métodos analíticos. Porém, a digestão total do cádmio apresentou valores inferiores ao limite de detecção (LOD), o que inviabilizou o estudo das extrações sequenciais e de biodisponibilidade. Portanto, para este elemento foi feito apenas o ensaio de adsorção. Para validação da extração sequencial e digestão total do analito, foram utilizados os materiais de referência certificados BCR-701 e SRM-2586, respectivamente. Foi observada uma correlação positiva entre a concentração total de Pb e o pH, Capacidade de Troca Catiônica (CTC) e Matéria Orgânica (MO). A CTC, pela própria definição, promove maior troca de íons pelo solo, sendo maior a chance de encontrar íons contidos nela. Com a MO, esta última promove a quelação dos íons Pb, estabilizando-os. Os valores encontrados para Pb nos solos coletados variaram de 6,44 ± 0,29 a 19,0 ± 3,9 g g-1. A mobilidade e biodisponibilidade de Pb são baixas, devido à conversão deste elemento em espécies mais estáveis, conforme constatado nos resultados da extração sequencial, nas etapas 3 (fração ligada à matéria orgânica) e 4 (fração residual); e no ensaio de biodisponibilidade, o qual corresponde, às etapas 1 (fração facilmente trocável) e 2 (fração ligada a óxidos de Fe e Mn), quando comparamos os valores obtidos. Para o chumbo, a fração facilmente lixiviada representa um mínimo em relação à concentração total, o que reforça a alta inertização do Pb em solos. Para ambos analitos, o perfil de adsorção no solo encaixa-se na Isoterma de Langmuir (melhor coeficiente de correlação linear), a qual se baseia na suposição de que a adsorção máxima corresponde ao ponto de saturação da superfície do adsorvente, portanto encontra-se um grau de adsorção limitante. Não é observada contaminação de chumbo e cádmio nos solos, segundo referência da CETESB (17 e 0,5 g g-1, respectivamente); e apenas entre 7 a 18 % de chumbo pode se apresentar biodisponível; as frações que contém maior concentração são as formas mais estáveis, o que dificulta a lixiviação do elemento chumbo para o aquífero / The region of Ribeirão Preto stands on the national scene due to its agricultural activities, mainly the cultivation of sugar cane. There is also a large hydro potential in the region: the city of Ribeirão Preto is supplied at 100 % by the Guarani Aquifer, which is a groundwater reservoir. Thus, a study comprising the mobility and bioavailability of Pb and Cd in the upper layer of soil of Ribeirão Preto, particularly in areas of recharge and/or upwelling of the Guarani Aquifer, and in active or disabled landfill areas has been carried out. In the current study, the following items were investigated: (1) the concentration of Pb and Cd in the topsoil, (2) retention and potential mobility of Pb and Cd using simple and sequential extraction procedures, (3) the estimated adsorption capacity. All measurements were accomplished by flame atomic absorption spectrometry (F AAS) and electrothermal atomization (ET AAS). For the acid digestion, the USEPA 3050B procedure was employed. The sequential extraction procedure (BCR protocol) was used in distribution studies of analytes in soils as well as their mobility. Also, a modified BCR protocol for tropical soils was employed for later comparison. The bioavailability evaluation was carried out with EDTA as the extracting agent. For the batch-type adsorption procedure, the stirring time was optimized in 2 h. The equations of linear, Langmuir and Freundlich isotherms were applied. There was no difficulty in lead determination, whose concentrations were within the calibration curve and above the limit of quantification (LOQ), according with the figures of merit for the analytical methods. However, the total digestion of cadmium was lower than the limit of detection (LOD), which made the study of sequential extractions and bioavailability unviable. So, for this element only the adsorption test was made. To validate the sequential extraction and total digestion of the analyte, certified reference materials BCR-701 and SRM-2586 were used, respectively. A positive correlation between the total concentration of Pb and pH, Cation Exchange Capacity (CEC) and Organic Matter (OM) was observed. The CEC, by definition, promotes larger ions exchange through the soil, with a higher chance of finding these ions contained therein. The OM promotes the chelation of Pb ions, stabilizing them. The obtained values for Pb in the collected soils ranged from 6.44 ± 0.29 to 19.0 ± 3.9 g g-1. Mobility and bioavailability of lead are low due to the conversion of this element into more stable species, as seen in the sequential extraction results in the steps 3 (fraction bound to organic matter) and 4 (residual fraction) and the bioavailability test, which corresponds to steps 1 (easily exchangeable fraction) and 2 (fraction bound to Fe and Mn oxides), when comparing the values. For lead, the easily leached fraction represents a minimum in relation to the total concentration, which reinforces the high blanketing of Pb in soils. For both analytes, the profile of soil adsorption fits the Langmuir Isotherm (best linear correlation coefficient), which is based on the assumption that the maximum adsorption corresponds to the saturation point of the adsorbent surface, so there is a degree of a limiting adsorption. Lead contamination is not observed in these soils, according with the CETESB reference (17 and 0.5 g g-1, respectively); only the lead percentage between 7 and 18% may be bioavailable; the fractions containing the highest concentration are the most stable forms, which hinder the leaching of the element lead for the aquifer

Foram utilizados 504 pintos de corte, machos, da linhagem Cobb, de 1 dia de idade, distribuídos aleatoriamente em 18 tratamentos com 4 repetições pelo período de 21 dias, para determinar a biodisponibilidade relativa do fósforo (BRP) em farelo de trigo, soja integral tostada ou extrusada com e sem a adição de fitase. Foram adicionados dois níveis de fitase (0 ou 750 FTU/kg dieta) e dois níveis de fósforo suplementar (0,05 ou 0,10%) à dieta basal semi-purificada com baixo nível de fósforo total (0,40%) sendo a fonte padrão de fósforo o fosfato bicálcico. Ao término do experimento, foram removidas as tíbias esquerdas e os dedos médios direitos para posterior análise de cinzas ósseas. A BRP para cada fonte orgânica foi calculada pelo método do “slope ratio” através da regressão dos valores de peso de cinzas na tíbia em função dos níveis de fósforo suplementar ingerido (mg/dia). Os valores de BRP para farelo de trigo, soja integral tostada e extrusada sem a adição de fitase foram de 74,4; 56,9 e 56,5%, respectivamente. Com a adição de fitase estes valores foram para 79,4; 93,5 e 100%, respectivamente. / Five hundred and four male Cobb chicks were used in a 21 day study to determine the relative bioavailability of phosphorus (RBP) in wheat midds, or soybean roasted or extruded with and without added microbial phytase (0 or 750 FYT/kg of diet).The reference standart was a purified grade calcium phosphate dibasics (DPS). The experimental ingredients, as well as the DPS, were added to the semi-purified starch-soybean meal control diet (22% protein; 0,32% P + 0,08% P from DPS) provinding 0,05 and 0,10% additional P, for a total of 9 experimental diets containing 0 FYT/kg, plus a second group of 9 diets containg 750 FYT/kg of diet. Slope ratio technique was used to calculate RBP, based on tibia bone ash weigt (TIAW) or toe bone ash weight (TOAW), regressed on added P intake within each P source. Coefficient of determination were higher to TIAW, so these values were used to express RBP. With no phytase added to the diet RBP values were 74,4 (wheat midds), 56,9 (soybean roasted) and 56,5% (soybean extruded), and the addition of 750 FYT/kg of diet increased these values to 79,4; 93,5 and 100%, respectively.

Foi objetivo do presente estudo avaliar a biodisponibilidade relativa do fósforo a partir de fosfatos comerciais usados na alimentação animal, utilizando-se de 680 pintos de corte, machos, da linhagem Ross, de 1 dia de idade, distribuídos aleatoriamente em 17 tratamentos no período de 21 dias. Foram adicionados dois níveis de fósforo suplementar (0,08 e 0,16%) à dieta basal com baixo nível de fósforo total (0,40%), sendo a fonte padrão de fósforo o fosfato bicálcico quimicamente puro. A biodisponibilidade do fósforo para cada fosfato comercial foi calculada pelo método do "slope ratio" através da regressão dos valores dos parâmetros ósseos (cinzas da tíbia e dedos médio) e desempenho animal (ganho de peso, consumo de ração e conversão alimentar). Os valores de ganho de peso, consumo de ração, conversão alimentar e parâmetros ósseos aumentaram em resposta aos incrementos de P na dieta, independentemente da fonte de fósforo. Valores de BRP foram calculados a partir do peso das cinzas nos dedos médio aos 21 dias, sendo que o mais alto valor foi obtido pelo fosfato monossódico quanto comparado aos demais fosfatos testados. / The relative bioavailability of phosphorus was studied in a trial with 680 male Ross chicks used in a 21 day .Phosphates were added to the basal diet to provide 0,08 and 0,16% supplemental P. The reference standard was a purified grade calcium phosphate dibasics. Slope ratio technique was used to calculate relative bioavailability of phosphorus, based on bone parameters (tibia and toe ash) and body weight gain, feed intake and feed:gain ratio. At day 21, body weight gain, feed intake, feed:gain ratio and bone parameters increased with incremental levels of P in the diet regardless of source. Relative bioavailability of phosphorus based on toe ash was higher from monosodium phosphate as compared with studies phosphates.

Frutanos, frutooligossacarídeos (FOS) e inulina, são carboidratos constituídos de moléculas de frutose, ligadas ou não a uma molécula terminal de sacarose e, devido aos efeitos fisiológicos do seu consumo, são incluídos na categoria das fibras alimentares. Estudos têm demonstrado que os frutanos são intensamente fermentados no intestino grosso proporcionando, desta forma, um ambiente favorável para a absorção dos minerais. No presente trabalho, os efeitos dos FOS, provenientes da Raftilose e da raiz tuberosa do yacón, foram avaliados sobre a biodisponibilidade do Ca e do Mg em ratos em crescimento. Foram realizados dois ensaios biológicos, sendo o 1º de 23 dias (n=16) e o 2º de 27 dias (n=24). Ratos machos da linhagem Wistar Hannover, recém-desmamados, foram submetidos, no 1º ensaio, a dietas suplementadas com Raftilose (5% de FOS) e, no 2º ensaio, com uma farinha de yacón (5 e 7,5% de FOS). Em ambos, os ensaios a ração controle foi elaborada segundo a AIN-93G. Todas as rações foram suplementadas com 7,5g de cálcio/kg de ração. Ração e água foram fornecidas ad libitum. Fezes (1º e 2º ensaios) e urina (2º ensaio) foram coletadas ao longo de 3 períodos experimentais (4º, 10º e 16º dias de experimento) de 5 dias cada. Os animais foram sacrificados e o fígado, o baço e os rins foram removidos e pesados. O ceco foi removido e seu conteúdo e sua parede foram pesados. Após centrifugação do conteúdo, as frações resíduo (R) e sobrenadante (S) foram pesadas e o pH foi determinado na fração S com uma fita indicadora. No 2º ensaio uma porção da parede do ceco e do cólon proximal foram fixados em solução alcoólica de Bouin e posteriormente transferidos para uma solução de etanol a 70%, para análises histológicas. Os ossos (fêmur e tíbia) foram removidos para análises da densidade mineral óssea (DMO), do conteúdo mineral e das propriedades mecânicas (somente o fêmur). As análises de Ca e Mg também foram realizadas nas fezes (absorção aparente), na urina (balanço mineral) e no conteúdo cecal. Os resultados foram avaliados através de análises de variância (ANOVA), sendo considerado um nível de significância de 95%. Foram observados aumentos significativos no peso e no teor de umidade das fezes, e no peso do ceco (conteúdo e parede). O consumo dos FOS estimulou significativamente a absorção e o balanço mineral. Tal efeito ocorreu de maneira menos pronunciada para o Mg. Este aumento foi refletido em maior retenção mineral nos ossos, confirmada pelas análises por espectrofotometria de absorção atômica. Foi observado efeito positivo nas propriedades mecânicas (carga máxima e rigidez) nos fêmures dos animais que consumiram FOS, em relação às dos grupos controles. Não foram observadas diferenças significativas na DMO, em quaisquer das regiões analisadas nos ossos (proximal, medial e distal), entre os grupos experimentais. As análises histológicas demonstraram um pronunciado aumento na profundidade e no número de criptas no ceco, bem como no número de criptas em bifurcação. Os efeitos positivos na absorção intestinal, na retenção mineral e no comportamento mecânico do osso observado no presente estudo, indicam um papel importante dos FOS na manutenção de ossos hígidos. / Fructans, fructooligosaccharides (FOS) and inulin, are carbohydrates comprising fructose molecules linked or not to a terminal sucrose molecule. Because of the biological effects of its consumption, they are considered as fibers. Studies have demonstrated that fructans are intensely fermented in the large intestine, thus rendering a favorable environment to mineral absorption. In the present work, the effects of FOS from Raftilose and from yacon tuberous roots on the bioavailability of Ca and Mg in growing rats were evaluated. Two biological assays were carried out, the first one lasting 23 days (n=16) and the second one lasting 27 days (n=24). In the first assay, weanling male Wistar Hannover rats were fed diets supplemented with Raftilose (5% FOS). In the second assay, they were fed diets supplemented with yacon flour (5 and 7.5% FOS). In both assays, the control diet followed AIN-93G. All diets were supplemented with 7.5g calcium/kg diet. Diet and water were given ad libitum. Feces (first and second assays) and urine (second assay) were collected along the 3 experimental periods (4th, 10th and 16th days of experiment), each period lasting 5 days. The animals were sacrificed and their livers, spleens and kidneys were removed and weighed. The cecum was removed and its contents and wall were weighed. After centrifuging the contents, residues (R) and supernatant (S) were weighed and the pH of S was determined using a chemical tape. In the second assay, portions of the cecum and proximal colon walls were fixed in Bouin’s alcoholic solution and then transfered to a 70% ethanol solution, aiming histological analyses. The bones (femur and tibia) were removed for bone mineral density (BMD) analyses, mineral contents and mechanical properties (only the femur). Ca and Mg analyses were also performed on the feces (apparent absorption), urine (mineral balance) and cecal contents. The results were evaluated using analysis of variance (ANOVA), considering a significance of 95%. Significant increases in the weight and moisture of feces and in the weight of the cecum (contents and wall) were observed. Besides, the consumption of FOS significantly stimulated the absorption and mineral balance, although such an effect was not so evident for Mg. That increase was reflected in a greater bone mineral retention, confirmed through atomic absorption spectrophotometry analyses. A positive effect on mechanical properties (maximum load and hardness) was observed in the femur of animals feeding on FOS, relatively to the control groups. On the other hand, no significant differences in BMD were observed in any of the bone regions analysed (proximal, midshaft and distal) among the experimental groups. Histological analyses demonstrated a noticeable increase in the depth and number of cecum crypts, as well as in the number of bifurcated crypts. The positive effects on intestinal absorption, mineral retention and mechanical behavior of the bones, observed in the present study, show an important role of FOS in healthy bones.

Ce travail a pour objectif la mise en place d'un procédé de phytostabilisation sur un ancien site industriel, la Vieille Usine d'Auzon (43, France). La caractérisation pédochimique du site atelier a révélé une pollution polymétallique par l'As, Pb, Sb, Cd et Cu. L'As, de par sa concentration totale et sa biodisponibilité dans le sol, est considéré comme le polluant le plus présent et le plus toxique. L'étude floristique réalisée sur le site a relevé une flore métallicole dominée par des pseudométallophytes électives telles que Agrostis capillaris, Equisetum arvense, ou les Euphorbiacées. De manière générale, la majorité des espèces présentes sur la friche industrielle a accumulé de très faibles quantités de polluants (As, Pb) dans ces parties aériennes. Dans un deuxième temps, les travaux ont porté sur les effets induits par les ETM au niveau physiologique et biochimique chez des modèles végétaux, Agrostis capillaris, Solanum nigrum, Vicia faba et Cannabis sativa. Ces données ont mis en évidence la sensibilité de V. faba et la tolérance de S. nigrum à la pollution aux ETM, un maintien de l'activité physiologique mais un ralentissement de la croissance de C. sativa sur sol pollué et une tolérance adaptative d'A. capillaris à la pollution du sol. Par ailleurs, une culture en hydroponie de S. nigrum et V. faba en présence d'As inorganique, arsénite et arséniate, à différentes concentrations a permis de mettre en évidence deux effets de l'As. Celui-ci a provoqué une altération de la structure et du fonctionnement des PSII, plus sensibles à l'As(III), et, une inhibition de l'activité oxygénase et carboxylase de la Rubisco, cible privilégiée de l'As(V). Enfin, ces résultats ont été utilisés dans le cadre de l'expérimentation in situ pour la validation d'un procédé de phytostabilisation sur la friche industrielle d'Auzon. Les effets de la combinaison d'une association d'espèces prairiales et d'un amendement de grenaille de fer zérovalent ou/et de compost ont pu être caractérisés. L'ajout de grenaille de fer au sol complété par un apport de compost a accentué la réduction de la disponibilité de l'As et dans une moindre mesure de Sb. De plus, il a permis d'enrichir le sol en élément minéraux et organiques et a ainsi facilité l'implantation d'un couvert végétal constitué d'espèces végétales à phénotype d'exclusion. Cette expérience in-situ a donc permis de mettre en avant la faisabilité d'un procédé de phytostabilisation dans la dépollution et la revalorisation de sites industriels. / This work aims to the establishment of a phytostabilization process on an old industrial site, "La Vieille Usine" in Auzon (43, France). The pedochemical characterization revealed a polymetallic pollution by As, Pb, Sb, Cd, Cu. The As, by its total content and its bioavailability, is considered as the most concentrated and toxic. A floristic study noted a metallicolous flora dominated by elective pseudometallophyte species such as Agrostis capillaris, the dominant specie, Equisetum arvense, or Euphorbiaceae. Broadly speaking, the majority of species on the industrial site has accumulated very low amounts of pollutants (As, Pb) in these shoots. To better understand the trace element effects on different plants, Agrostis capillaris, Solanum nigrum, Cannabis sativa and Vicia faba were grown on the Auzon’s soil under controlled conditions. These data highlighted (i) the sensitivity of V. faba and the tolerance of S. nigrum to trace element pollution; (ii) for C. sativa, the maintenance of its physiological activity but a slowdown of its growth; (iii) the adaptative tolerance of A. capillaris to soil pollution. In addition, a hydroponics culture of S. nigrum and V. faba in the presence of different concentrations and different oxidation degrees (arsenite and arsenate) of inorganic As allowed to identify two main effects of As at physiological and biochemical level. First, it alters the structure and function of PSII, which seems more sensitive to As(III), and, secondly, it inhibits the carboxylase and oxygenase activities of Rubisco, the main target of As(V). These data were then used to conduct an in-situ experiment based on a phytostabilization process on the industrial wasteland of Auzon. The effects of the combination of an grassland species association with a zerovalent iron shot and/or compost amendment were characterized. The addition of iron shot on the soil completed with compost decreased the available fraction of As and to a lesser extent Sb. Moreover, the amendments allowed to enrich the soil with mineral and organic elements and to facilitate the establishment of vegetal cover composed by tolerant plants with an exclusion phenotype. This in-situ experience enabled to highlight the feasibility of a phytostabilization method in the depollution of industrial sites as in their enhancement.

Numerous experiments in recent years have indicated differences in the bioavailability of corticosteroids from seemingly identical topical dosage forms. The human blanching assay was utilized in this study to assess the comparative blanching activities of various locally manufactured proprietary corticosteroid preparations. The first experiment was performed to assess the relative blanching activities of six semi - solid preparations containing the same concentration of betamethasone 17-valerate. The preparations used were Betnovate cream and ointment, Persivate cream and ointment and Celestoderm-V cream and ointment. This was followed, in the second experiment, by the investigation of the blanching activities of two lotions containing betamethasone 17-valerate (Betnovate and Celestoderm-V) and a lotion containing betamethasone 17,21- dipropionate (Diprosone). The third experiment involved a study of six semi-solid proprietary corticosteroid-containing formulations, viz. Dermovate (clobetasol propionate) cream and ointment, Betnovate (betamethasone 17-valerate) cream and ointment and Eumovate (clobetasone butyrate) cream and ointment. This investigation was prompted by claims in advertisements in the medical media that Dermovate is therapeutically more efficacious than Betnovate which is more efficacious than Eumovate. The penultimate experiment in this study served the purpose of finding a corticosteroid-containing preparation that falls into the moderately potent group of corticosteroid formulations, as described in the United Kingdom MIMS. This preparation was used in the final experiment which was undertaken to ascertain the potency category of Florone (diflorasone diacetate) cream and ointment.

No description available.

Erythromycin is a macrolide antibiotic with a spectrum similar to penicillin and is used mainly in the treatment of infections caused by gram-positive organisms. Since its discovery in 1952, erythromycin has achieved wide-spread clinical use. Susceptibility of erythromycin base to inactivation by acid results in decreased availability following exposure to acidic gastric fluids. Formulation of acid resistant dosage forms and the preparation of acid stable chemical derivatives have been attempted to improve absorption and subsequent clinical efficacy . Two of the most commonly used erythromycin derivatives are the stearic acid salt (erythromycin stearate) and the lauryl sulphate salt of the propionyl ester (erythromycin estolate). Although it has been known for many years that erythromycin is susceptible to acid degradation, very few reports on the stability of erythromycin in aqueous solutions appear in the literature. In this study, a high-performance liquid chromatographic system using electrochemical detection was employed for a kinetic study of erythromycin degradation. The effect of varying acid pH on the degradation rate of both erythromycin base and erythromycin stearate, and the effect on the hydrolysis rate of erythromycin estolate is presented. In addition, the effect of temperature on erythromycin degradation was also investigated. Until recently, the majority of pharmacokinetic and bioavailability studies have utilized relatively non-specific microbiological assay procedures. However, in this study a solid phase extraction, followed by the use of a high-performance liquid chromatographic system using electrochemical coulometric detection was employed for the determination of erythromycin in biological fluids. Human volunteers each received enteric coated erythromycin base pellets in capsule dosage form and also film coated erythromycin stearate tablets on separate occasions. Results from the clinical trials revealed the enteric coated erythromycin base pellets had a greater bioavailability than the film coated erythromycin stearate tablets. Computer fitting of data revealed no intra-volunteer variability in elimination rate constants, suggesting differences in serum levels following administration of both dosage forms are due to variation in absorption. Results from the clinical trials were also compared with those obtained from a further trial, during which the same volunteers received erythromycin estolate

In 2003 the Department of Health of South Africa embarked on a mandatory fortification programme of maize meal as part of the Integrated Nutrition Program (INP) to alleviate malnutrition. The aim of this study was two-fold: firstly, to determine the vitamin A content of South African fortified white maize meal as purchased and the maize porridge as traditionally prepared from it as consumed and secondly, to determine the relative efficacy of the daily consumption of maize meal in sustaining or improving vitamin A status. Maize meal samples for analysis were purchased from various supermarkets and small retail outlets. A High Performance Liquid Chromatograph-Diode Array Detector system with a Reverse Phase C-18 column and isocratic elution was used for separation and quantification of vitamin A. The highest mean vitamin A concentration measured in the maize meal was 261 μgRE/100g and the lowest mean vitamin A concentration was <19 μgRE/100g. Pertaining to the regulations the final minimum level of vitamin A in fortified maize meal must not be less than 187.7 μgRE/100g. The average retention of vitamin A in maize porridge as the difference in vitamin A concentration measured between raw maize meal and cooked porridge was calculated at 39.8%. One of the considerations in a fortification program is the availability of certain micronutrients in the fortified foods, with the focus in this project on vitamin A. An animal model, namely chickens, closely relating the metabolism of vitamin A in humans was used. Chickens are very susceptible to vitamin A deficiencies with similar symptoms. Growth and vitamin A status was evaluated by the weight, feed conversion and liver retinol stores of chickens on five different maize based diets over a six week period. No significant difference in vitamin A levels in the livers of birds on diets with fortified white maize meal, compared to the normal poultry diet consisting of yellow maize meal with added vitamin A was found. It can thus be concluded that the fortificant in the white maize meal is as bioavailable as the vitamin A in the premix used in poultry nutrition. The results of this study show that the vitamin A added as fortificant is absorbed and available to the body. Therefore, fortification of commonly eaten staple foods in the country can significantly improve the vitamin A intake of the population and will improve the overall micronutrient density of their diets. Fortification should be set at levels to include losses incurred through packaging and during transportation, shelf losses and preparation losses. It is also important that the vitamin A content of the product as purchased and consumed must be regularly monitored and regulated by government. Valid and reliable evaluation data are needed to evaluate a program’s success, and to make timeous adjustments for optimal efficiency. / Thesis (PhD)--University of Pretoria, 2011. / Animal and Wildlife Sciences / unrestricted

Não consta resumo na publicação. / Abstract not available.