Thesis (M.Sc. in Biochem.) -- Mahidol University, 1969.

Phytoestrogens are very intensively studied in recent years because they show different pharmacological effects on human health. For example, it was demonstrated that phytoestrogens reduce the risk of certain cancers (breast, prostate or colon), act as antioxidants in the body and affect the activity of certain enzymes. In addition, also it was demonstrated number of positive effects of soybean phytoestrogens on the health status of women in the menopause, such as reducing the risk of atherosclerotic cardiovascular disease or osteoporosis. Various technologically processed soy beans are important part of the feed rations mainly for high-lactating dairy cows, because they are a valuable source of the energy and high-quality protein, despite their negative effect on reproductive performance. Phytoestrogens consumed from the feed rations are hydrolyzed in the rumen of dairy cow and together with their metabolites are absorbed in the small intestine into the blood. They can be excreted from the body in urine or milk. From this perspective, cow's milk may become a source of phytoestrogens substances, especially equol in the human nutrition. On the other hand, some research results suggest possible potential risks associated with phytoestrogens intake in the diet on human health. At the some age (infants and young children) and group (vegetarians) categories may be dietary intake of phytoestrogens undiserable. According to most experts, a beneficial effect on human health prevail the potential risks. However, the risks associated with phytoestrogens intake in food can not be ignored and therefore phytoestrogens are still actual problem in the field of scientific research.

Resumo: Objetivou-se avaliar o efeito de suplementos lipídicos disponíveis em diferentes formas (soja em grão moído, óleo de soja, e sais de cálcio - SC) no consumo de matéria seca total; comportamento ingestivo; desempenho corporal; parâmetros de fermentação ruminal; características de carcaça; desenvolvimento e composição corporal; e na qualidade da carne de novilhas mantidas em pastagens de Brachiaria brizantha cv. Marandu suplementadas em duas frequências (diária ou segunda, quarta e sexta - SQS). O experimento foi realizado nos meses de julho a novembro de 2007. Foram utilizadas novilhas mestiças (1/4 Nelore x 1/4 Santa Gertrudis x 1/2 Braunvieh), alimentadas com três suplementos lipídicos na quantidade de 0,75% do peso corporal. Os dados foram analisados em delineamento inteiramente casualisados com os tratamentos em arranjo fatorial (3x2 - três suplementos lipídicos e duas frequências alimentares). O consumo de matéria seca total foi maior nos meses de agosto e outubro em relação ao mês novembro. Houve efeito das formas de fornecimento da fonte lipídica sobre o consumo em kg de matéria seca total, forragem e nutrientes. Durante o período seco e início das águas os animais obtiveram ganhos médios totais de 0,577g dia-1, que não foram influenciados pelas suplementos lipídicos e frequências de suplementação utilizadas. A redução na frequência de suplementação alterou o tempo de pastejo em função dos suplementos lipídicos. Não houve influência dos suplementos lipídicos e das frequências de suplementação sobre o balanço de compostos nitrogenados, na síntese e eficiência de proteína microbiana. Houve influência das formas de fornecimento dos suplementos lipídicos sobre os valores de pH ruminal. A menor frequência de suplementação proporcionou diferenças nas concentrações de nitrogênio amoniacal ruminal... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: This research aimed to evaluate total dry matter intake, feeding behavior, growth performance, rumen fermentation parameters; carcass characteristics, development and body composition, and meat quality responses of steers grazing Brachiaria brizantha cv. Marandu supplemented at two frequencies (daily or Monday, Wednesday and Friday - MWF), under different forms of lipid supplements (soybean grain, soybean oil, and calcium salts - CS). This research was conducted throughout a four month period during the dry season (July to November 2007). Crossbred heifers were used (1/4 Nellore x 1/4 Santa Gertrudis x 1/2 Braunvieh) fed with three lipid supplements in the amount of 0.75% of body weight. The experiment was completely random, using a 3x2 factorial arrangement (3 supplements and 2 supplementation frequencies). The total dry matter intake was higher in August and October compared to November. There was effect of the lipids forms supplied on total dry matter, forage and nutrients intake. During the dry season and beginning of the wet season the animals showed average daily gain of 0.577 g day-1, which were not affected by dietary lipid supplementation and frequencies used. The kind of lipid diet under reduction on the frequency of supplementation alter grazing time. There was no influence of diet lipid and frequencies supplementation on nitrogenous compounds, in the synthesis and efficiency of microbial protein. There was influence of the lipids forms diets on values of rumen pH. Supplementation provided under frequency differences in the concentrations of ammonia in the rumen. There was influence of the lipids forms diets on weight hot carcass, and weight and dress percentage. Supplementation with dietary lipids under different forms and frequencies does not provide differences in body composition... (Complete abstract click electronic access below) / Orientadora: Telma Teresinha Berchielli / Coorientador: Ricardo Andrade Reis / Banca: Alexandre Amstalden Moraes Sampaio / Banca: Ana Cláudia Ruggieri / Banca: Marco Antonio Alvares Balsalobre / Banca: Juliano José de Resende Fernandes / Doutor