• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 2
  • 1
  • 1
  • Tagged with
  • 4
  • 4
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 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.
1

Physiological stress and behavioural differences in broiler breeder hens subjected to daily and 5:2 feed restriction regimens

Johansson, Alexandra January 2016 (has links)
Feed restriction in the parental stock of meat producing chickens, broiler breeders, is essential in order to decrease the high growth rate that they are genetically selected for. The feed restriction does however lead to chronic hunger and stress. Stress can be measured by counting H/L ratios and the method of manually counting H/L ratios was evaluated. The method was not a good way to ensure reliable individual H/L ratios but still gives an H/L ratio indication on a group level and was therefore still used in the study. Two different feeding regimens were investigated in the study: 5:2 skip-a-day (SKIP) with two fasting days and daily feed restriction (CTRL), with chickens sampled at 9 and 12 weeks of age. There was no significant difference in body mass between the treatments at either age. SKIP chickens had significantly higher H/L ratios compared to CTRL at 12 weeks of age (P=0.020), but both treatments had H/L ratios above the reported limit of stress (0.5). The SKIP group on a feeding day significantly increased plasma glucose levels during the day (10.3 to 11.5 mmol/L, P=0.020) and had significantly higher liver mass and liver glycogen levels compared to the CTRL (P≤0.001). The SKIP group were also less fearful on fasting days and significantly less active than the CTRL (P≤0.050), regardless of age or daily feed differences. The conclusion was that both treatments were stressed but skip-a-day chickens were habituated to their regimen and did not experience worse welfare than daily fed broiler breeders.
2

Cádmio na cadeia alimentar: proveniente de vegetais e avaliação da sua disponibilidade no solo com auxílio do 109Cd / Cadmium in food chain: derived from vegetables and evaluation of its availability in soil with the aid of 109Cd

Guerra, Fernando 02 June 2011 (has links)
A contaminação do ambiente é crescente no mundo, com grandes extensões de áreas afetadas por metais pesados em concentrações que podem representar perigo ambiental. Em face ao aumento da atividade industrial e à agricultura altamente tecnificada, é fundamental o monitoramento dos níveis de metais pesados nos solos, já que as plantas se comportam como mecanismo de transferência de contaminantes do solo para níveis mais altos da cadeia trófica. A ingestão de vegetais contendo elevadas concentrações de metais pesados é uma das principais vias de acesso desses elementos ao corpo humano. No corpo humano, os metais pesados depositam-se no tecido ósseo e gorduroso, ocupando o lugar de minerais nobres. Lentamente liberados no organismo, podem provocar uma série de doenças. O projeto foi dividido em três etapas, cada qual com um objetivo específico: 1º) determinar as concentrações de cádmio, níquel, chumbo, cobalto e cromo em vegetais frequentemente consumidos no Estado de São Paulo, e compará-las com os limites estabelecidos na legislação brasileira; calcular a ingestão diária de metais pesados para estimar o risco à saúde humana; identificar as culturas que apresentam maior potencial de translocação de cádmio para a cadeia alimentar 2º) avaliar os teores de cádmio em hortaliças e nos solos dos campos de produção 3º) avaliar a disponibilidade de cádmio do solo para as plantas com maior potencial de acúmulo do mesmo, com auxilio de extratores químicos e pela técnica de traçador radioativo (109Cd). As amostras vegetais foram coletadas na Companhia de Entrepostos e Armazéns Gerais de São Paulo e a concentração de metais pesados foi determinada por espectrometria de absorção atômica. Todos os vegetais analisados apresentaram concentrações de Cd e Ni abaixo do limite tolerável estabelecido pela legislação brasileira. No entanto, para Pb e Cr, 44% das amostras excederam o limite permitido. Não há nenhuma recomendação estabelecida de limite máximo de tolerância para Co no Brasil. Quanto ao hábito de consumo da população do Estado de São Paulo, a ingestão diária de metais pesados está abaixo da máxima permitida, consequentemente o consumo desses alimentos pode ser considerado seguro e sem riscos à saúde humana. As hortaliças folhosas foram as que mais acumularam Cd. Algumas regiões do Estado de São Paulo apresentaram teores totais de Cd no solo acima do valor de intervenção estabelecido pela CETESB. Entretanto, os vegetais cultivados nesses locais apresentaram teores de Cd inferiores ao limite máximo de tolerância, estabelecido pela ANVISA. É importante, ao estudar a contaminação de áreas agrícolas por metais pesados, observar, além do teor total, outros parâmetros, como a sua disponibilidade para plantas. No experimento em casa de vegetação, as correlações entre o Cd disponível do solo e o Cd acumulado pelas plantas foram significativas somente para a rúcula. O extrator mais eficiente em determinar a fitodisponibilidade de Cd, analisado por meio do Valor L e Razão L, foi o extrator Ácidos Orgânicos / The environmental contamination is increasing worldwide, with large areas affected by heavy metals at concentrations which may pose environmental hazard. Due to industrial activity and highly technical agriculture, it is important to monitor heavy metals levels in soils, since vegetables behave as transfer mechanism of contaminants from soils to higher levels of the food chain. Ingestion of vegetables containing high concentrations of heavy metals is one of the main ways in which these elements enter the human body. Once in human body, heavy metals are deposited in the bone and fat tissues, overlapping noble minerals. Slowly released into the body, heavy metals may cause an array of diseases. The project was divided into three stages, each one with a specific objective: 1st) to determine the concentrations of cadmium, nickel, lead, cobalt and chromium in the most frequently consumed foodstuff in the São Paulo State, Brazil and to compare the heavy metal contents with the permissible limits established by the Brazilian legislation; to calculate intake of heavy metals in human diets for estimating the risk to human health; and to identify crops with the greatest potential for translocation of cadmium into food chain 2nd) to evaluate the cadmium content in leafy vegetables and soils at crop fields 3th) evaluate the phytoavailability of cadmium for leafy vegetables with aid of chemical extractants and radioactive tracer technique (109Cd). The vegetable samples were collected at São Paulo General Warehousing and Centers Company, and heavy metal content was determined by atomic absorption spectrophotometry. All vegetables sampled presented average concentrations of Cd and Ni lower than the permissible limits established by the Brazilian legislation. Exception for Pb and Cr in that 44% of the samples exceeded the maximum permitted limits. The Brazilian legislation has not established a permissible limit for Co contents. Regarding the consumption habit of the population in the São Paulo State, the daily ingestion of heavy metals is below the oral dose of reference, therefore, the consumption of these vegetables can be considered safe and without risk to human health. Leafy vegetables were those most accumulated Cd. Some regions of São Paulo State showed total contents of Cd in soil higher than intervention value established by CETESB. However, the vegetables grown in these areas showed Cd concentrations lower than Brazilian limit established by ANVISA. It is important, when studying environmental contamination by heavy metals, to observe, beside their total content, other parameters, like soil availability. In the greenhouse experiment, the correlation between soil available Cd and plants accumulated Cd were significant only for rocket. The most efficient chemical extractant in determining Cd phytoavailability, analyzed by L Value and L Ratio, were Organic Acids
3

Cádmio na cadeia alimentar: proveniente de vegetais e avaliação da sua disponibilidade no solo com auxílio do 109Cd / Cadmium in food chain: derived from vegetables and evaluation of its availability in soil with the aid of 109Cd

Fernando Guerra 02 June 2011 (has links)
A contaminação do ambiente é crescente no mundo, com grandes extensões de áreas afetadas por metais pesados em concentrações que podem representar perigo ambiental. Em face ao aumento da atividade industrial e à agricultura altamente tecnificada, é fundamental o monitoramento dos níveis de metais pesados nos solos, já que as plantas se comportam como mecanismo de transferência de contaminantes do solo para níveis mais altos da cadeia trófica. A ingestão de vegetais contendo elevadas concentrações de metais pesados é uma das principais vias de acesso desses elementos ao corpo humano. No corpo humano, os metais pesados depositam-se no tecido ósseo e gorduroso, ocupando o lugar de minerais nobres. Lentamente liberados no organismo, podem provocar uma série de doenças. O projeto foi dividido em três etapas, cada qual com um objetivo específico: 1º) determinar as concentrações de cádmio, níquel, chumbo, cobalto e cromo em vegetais frequentemente consumidos no Estado de São Paulo, e compará-las com os limites estabelecidos na legislação brasileira; calcular a ingestão diária de metais pesados para estimar o risco à saúde humana; identificar as culturas que apresentam maior potencial de translocação de cádmio para a cadeia alimentar 2º) avaliar os teores de cádmio em hortaliças e nos solos dos campos de produção 3º) avaliar a disponibilidade de cádmio do solo para as plantas com maior potencial de acúmulo do mesmo, com auxilio de extratores químicos e pela técnica de traçador radioativo (109Cd). As amostras vegetais foram coletadas na Companhia de Entrepostos e Armazéns Gerais de São Paulo e a concentração de metais pesados foi determinada por espectrometria de absorção atômica. Todos os vegetais analisados apresentaram concentrações de Cd e Ni abaixo do limite tolerável estabelecido pela legislação brasileira. No entanto, para Pb e Cr, 44% das amostras excederam o limite permitido. Não há nenhuma recomendação estabelecida de limite máximo de tolerância para Co no Brasil. Quanto ao hábito de consumo da população do Estado de São Paulo, a ingestão diária de metais pesados está abaixo da máxima permitida, consequentemente o consumo desses alimentos pode ser considerado seguro e sem riscos à saúde humana. As hortaliças folhosas foram as que mais acumularam Cd. Algumas regiões do Estado de São Paulo apresentaram teores totais de Cd no solo acima do valor de intervenção estabelecido pela CETESB. Entretanto, os vegetais cultivados nesses locais apresentaram teores de Cd inferiores ao limite máximo de tolerância, estabelecido pela ANVISA. É importante, ao estudar a contaminação de áreas agrícolas por metais pesados, observar, além do teor total, outros parâmetros, como a sua disponibilidade para plantas. No experimento em casa de vegetação, as correlações entre o Cd disponível do solo e o Cd acumulado pelas plantas foram significativas somente para a rúcula. O extrator mais eficiente em determinar a fitodisponibilidade de Cd, analisado por meio do Valor L e Razão L, foi o extrator Ácidos Orgânicos / The environmental contamination is increasing worldwide, with large areas affected by heavy metals at concentrations which may pose environmental hazard. Due to industrial activity and highly technical agriculture, it is important to monitor heavy metals levels in soils, since vegetables behave as transfer mechanism of contaminants from soils to higher levels of the food chain. Ingestion of vegetables containing high concentrations of heavy metals is one of the main ways in which these elements enter the human body. Once in human body, heavy metals are deposited in the bone and fat tissues, overlapping noble minerals. Slowly released into the body, heavy metals may cause an array of diseases. The project was divided into three stages, each one with a specific objective: 1st) to determine the concentrations of cadmium, nickel, lead, cobalt and chromium in the most frequently consumed foodstuff in the São Paulo State, Brazil and to compare the heavy metal contents with the permissible limits established by the Brazilian legislation; to calculate intake of heavy metals in human diets for estimating the risk to human health; and to identify crops with the greatest potential for translocation of cadmium into food chain 2nd) to evaluate the cadmium content in leafy vegetables and soils at crop fields 3th) evaluate the phytoavailability of cadmium for leafy vegetables with aid of chemical extractants and radioactive tracer technique (109Cd). The vegetable samples were collected at São Paulo General Warehousing and Centers Company, and heavy metal content was determined by atomic absorption spectrophotometry. All vegetables sampled presented average concentrations of Cd and Ni lower than the permissible limits established by the Brazilian legislation. Exception for Pb and Cr in that 44% of the samples exceeded the maximum permitted limits. The Brazilian legislation has not established a permissible limit for Co contents. Regarding the consumption habit of the population in the São Paulo State, the daily ingestion of heavy metals is below the oral dose of reference, therefore, the consumption of these vegetables can be considered safe and without risk to human health. Leafy vegetables were those most accumulated Cd. Some regions of São Paulo State showed total contents of Cd in soil higher than intervention value established by CETESB. However, the vegetables grown in these areas showed Cd concentrations lower than Brazilian limit established by ANVISA. It is important, when studying environmental contamination by heavy metals, to observe, beside their total content, other parameters, like soil availability. In the greenhouse experiment, the correlation between soil available Cd and plants accumulated Cd were significant only for rocket. The most efficient chemical extractant in determining Cd phytoavailability, analyzed by L Value and L Ratio, were Organic Acids
4

Vliv stárnutí na změny v hematologických a imunologických znacích u sýkory koňadry (Parus major) / Effect of ageing on haematological and immunological traits in great tit (Parus major)

Krajzingrová, Tereza January 2019 (has links)
v III. Abstract (EN) According to the Disposable soma theory, senescence is mainly influenced by adaptive allocation of resources among the physical growth, reproduction and self-maintaining processes, which depend on expected survival of an individual. The amount of allocated resources may be influenced by external environmental factors such as heavy metal pollution or by inner factor e.g. reproduction. The aim of my diploma thesis was to clarify the relationships between senescence, selected haematological traits, reproduction and efficiency of innate immunity mechanism. Moreover, we are interested in the role of heavy metal pollution in ageing and haematology. The heterophiles to lymphocytes ratio (H/L) was used as a marker of long-term stress caused by these physiological expenses. This study summarizes partial data collected within the long-term research of great tits (Parus major) in Prague, Czech Republic, I participated in. We have more than 300 samples of repeatedly captured individuals at our disposal. The structure of this unique dataset allows us to observe changes in the traits of our interest during an avian lifespan. Our results show that during aging, males experience a noticeable increase in the H/L ratio compared to females. Although we have not found the effect of age on the brood size,...

Page generated in 0.0476 seconds