Maria Ignez Leão

Estimativa da produção de proteína microbiana pelos derivados de purinas na urina em novilhos

O trabalho foi realizado para avaliar a determinacao da producao de proteina microbiana com a utilizacao da excrecao urinaria de derivados de purinas; comparar a producao de proteina microbiana por intermedio dos metodos das bases purinas e da excrecao urinaria de derivados de purinas; determinar a producao de proteina microbiana em funcao do consumo de materia seca e da porcentagem de fibra em detergente neutro da racao; e estabelecer a proporcao de alantoina e acido urico, em relacao a xantina e hipoxantina na urina. Foram realizados cinco experimentos com animais fistulados no rumen, abomaso e ileo para estudos simultâneos de consumo, digestoes totais e parciais de nutrientes e eficiencia de sintese de proteina microbiana. Utilizou-se o delineamento experimental em quadrado latino 5x5, a excecao do experimento IV (4x4). Os dados foram agrupados em todos os experimentos, os que envolveram animais mesticos (I, II e III) e zebuinos (IV e V). Utilizou-se, para todos os dados agrupados, o delineamento inteiramente casualizado, em funcao dos niveis de concentrado da dieta. Da urina total coletada em 24 horas, foram analisados os derivados de purinas (alantoina, acido urico, xantina e hipoxantina) para determinar a producao microbiana. Para todos os experimentos agrupados, as excrecoes de derivados de purinas urinarios, representadas pela alantoina e pelas purinas totais, apresentaram comportamento quadratico em funcao dos niveis de concentrado da racao, acompanhando o comportamento do fluxo de compostos nitrogenados microbianos (N mic) estimado pelos derivados de purinas na urina, usando a relacao N purina:N total de 0,116, e o estimado pelas bases purinas no abomaso, encontrando-se valores maximos de 72,07 e 86,08 g N mic/dia, para niveis de 62,91 e 63,60% de concentrado, respectivamente. A relacao alantoina e acido urico:purinas totais foi de, aproximadamente, 98%, indicando que a concentracao de xantina e hipoxantina seria, em torno, de 2%.

Concentração plasmática de uréia e excreções de uréia e creatinina em novilhos

O trabalho foi conduzido com os objetivos de determinar a concentracao plasmatica de N-ureia (NUP), a excrecao fracional de ureia (EFU) e as excrecoes de ureia (EU) e creatinina (EC), para varias condicoes experimentais; estabelecer a relacao entre NUP, excrecao fracional de ureia e excrecao de ureia com a porcentagem de proteina bruta (PB) e fibra em detergente neutro (FDN) da dieta; e avaliar as perdas urinarias endogenas, por meio da determinacao da excrecao de creatinina. Nos experimentos I e II, foram utilizadas racoes constituidas de 25,0; 37,5; 50,0; 62,5; e 75,0% de concentrado formuladas para apresentarem niveis variados de proteina de acordo com a energia da dieta e niveis semelhantes de proteina (12% de PB), respectivamente. No experimento III, o nivel de concentrado foi fixo (40%), sendo variavel a idade de corte da graminea. No experimento IV, as racoes foram constituidas de 20,0; 32,5; 45,0; 57,5; e 70,0% de concentrado com, aproximadamente, 12% de PB. Utilizou-se o delineamento experimental em quadrado latino 5 x 5 para todos os experimentos, com excecao do III (4x4). Da urina total coletada em 24 horas, foram determinadas as excrecoes de ureia e creatinina. Para os experimentos I e III, a concentracao de NUP variou linearmente com a porcentagem de PB e FDN da dieta; a excrecao fracional de ureia e a excrecao de ureia tambem variaram da mesma forma para todos os experimentos. A excrecao de ureia aumentou linearmente com a concentracao de NUP. A excrecao de creatinina nao foi influenciada pelo teor de PB dietetico e foi proporcional ao peso corporal para todos os experimentos, com valor medio diario de 27,36 mg/kg PV, podendo ser usada para estimar as perdas endogenas de compostos nitrogenados.

Tamanho de Órgãos e Vísceras de Bezerros Holandeses, para Produção de Vitelos, Recebendo Dietas com Diferentes Níveis de Concentrado

The experiment was carried out with 20 intact Holstein male calves, 75 days old, with mean live weight of 76 kg, submitted to the same nursing system before starting the experiment. The objective was to evaluate the relative size of internal organs and viscera of these animals fed diets containing 45, 60, 75 and 90% of concentrate. Diets were composed of coastcross hay, ground corn grain, soybean meal and mineral mixture. The experimental design was a randomized blocks, with four treatments and five replicates. The experimental period was different for each treatment, where the animals were slaughtered as they reached a mean weight of 200 kg. Before slaughter, the animals were fasted for 16 hours. The absolute weights for the liver, kidneys, lungs, abomasum, mesentery and fat present in the carcass linearly increased as the levels of concentrate in the diets increased. There were no significant differences for the weight of the other organs and viscera, nor for the non constituint parts of the carcasses of the animals, as leather, feet, head and tail, in relation to the levels of the concentrate.

Características da Carcaça de Bezerros Holandeses para Produção de Vitelos Recebendo Dietas com Diferentes Níveis de Concentrado

The experiment was carried out with 20 Holstein intact male calves to study the carcass characteristics of these animals fed with diets containing 45, 60, 75 and 90% of concentrate. Diets were composed of coastcross hay, ground corn grain, soybean meal and mineral mixture fed ad libitum. A completely randomized blocks experimental design, with four treatments and five replications, was used. Before the beginning of the experiment, all animals were submitted to the same nursing system. The experimental period was different for each treatment, since the animals were slaughtered as they reached the average live weight of 200 kg. Before the slaughter, the animals were fasted for 16 hours. The left half carcasses were used to measure the loin eye area, length of carcass and their physical composition, and on the right half carcasses the basic cuts were made. The hot and cold carcass yields based on the live weight of the animals and the hot carcass yield based on the empty body weight and the loin eye area showed differences as the levels of concentrate in the diets increased. There were no significant differences for final live weight, hot carcass weight, cold carcass weight, cold carcass dressing based on the empty body weight, neither regarding the losses of weight of carcasses caused by the fasting period before slaughter, nor the basic cuts and nor the fore and hind quarter dressing.

Simulação e Validação de Parâmetros da Cinética Digestiva em Novilhos Mestiços Suplementados a Pasto, por Intermédio do Sistema In Vitro de Produção de Gases

Objetivou-se simular e validar a degradacao ruminal dos carboidratos e o fluxo nitrogenado microbiano, estimados a partir de parâmetros da cinetica de degradacao ruminal de amostras de extrusa esofagica e de suplementos obtidos pela tecnica in vitro de producao de gases. As estimativas in vivo foram obtidas em experimento de campo, no qual foram utilizados cinco novilhos mesticos Holandes x Zebu com idade e peso medios iniciais de 24 meses e 304 kg, manejados em cinco piquetes de B. decumbens (0,34 ha). Foram fornecidos suplementos (4 kg/animal/dia) constituidos por fuba de milho, grao de soja integral, ureia, sulfato de amonia e mistura mineral, formulados para apresentarem niveis de 12, 16, 20 e 24% de proteina bruta, com base na materia natural. O experimento foi conduzido em quatro periodos experimentais de 21 dias, em delineamento em quadrado latino 4 x 4. O quinto animal foi mantido sem suplementacao, sendo utilizado como medida de comparacao descritiva. A avaliacao estatistica foi feita por meio do ajustamento de equacao de regressao linear simples de valores preditos in vitro sobre valores observados in vivo. A utilizacao das taxas de digestao especifica obtidas in vitro implicou em sub e superestimacao da degradacao ruminal de carboidratos fibrosos (CF) e nao-fibrosos (CNF), cujos vicios globais do processo de de estimacao foram de -25,27% e +33,58%, respectivamente. Os valores preditos de eficiencia microbiana nao mostraram relacao significativa com os valores observados, refletindo falta de relacao entre valores preditos e observados para o fluxo abomasal de nitrogenio microbiano. A avaliacao de alimentos separadamente subestima a taxa de digestao especifica de CF.

Estimativa da produção microbiana em cabras lactantes alimentadas com diferentes teores de proteína na dieta

The objective of this trial was to study the effects of increasing dietary levels of crude protein (CP) on microbial protein synthesis of lactating dairy goats. The microbial markers purines bases and purine derivatives (PD), measured in spot urine samples or in urine samples from total collection, were used to estimate microbial protein synthesis. Sixteen lactating goats (four fitted with ruminal cannula) were randomly assigned to four replicated 4 x 4 Latin squares and were fed the following dietary CP levels [dry matter (DM) basis]: 11.5, 13.5, 15.5 or 17.5%. No significant differences were observed between techniques for estimating microbial protein synthesis. Therefore, 12 non-cannulated goats were used to evaluate the effect of dietary CP level on PD excretion, microbial nitrogen flow and microbial efficiency using either total or spot collection of urine. Because creatinine excretion did not differ among treatments, the average value 26.05 mg of urinary creatinine excreted per kg of body weight was used for estimating the volume of urine using spot samples. Urinary volume estimated using spot samples was similar to that measured with total urine collection. In both cases, an increase on the amount of absorbed purines was observed when the dietary CP level increased in the diet. In brief, PD can be used for estimating microbial protein synthesis in lactating goats and spot samples were a good alternative for total collection of urine.

Fontes de energia em suplementos múltiplos para novilhos em pastejo durante o período das águas

This study evaluated the supply of starch and fibrous energy in multiple supllements on the performance and nutritional characteristics of finishing crossbred Holstein × Zebu steers grazing Brachiara decumbens Stapf. in the rainy season. The experimental area was constituted of five 2 ha paddocks with dry matter average avaibility of 5,853.0 kg/ha. It was used 24 castrated crossbread steers aproximately at the age of 27 months and initial live weight of 377.03 ± 7.28 kg. It was given to each animal one of the following suplements: mineral mixture ad libitum, sorghum grain or corn grain as starch energy sources, and soybean hulls or wheat bran as fibrous energy sources. For the energy sources, the following were added: mineral mixture, cotton seed meal and urea to compose suplements with 33% crude protein based on dry matter given at 1.0 kg/animal/day proportion. For the animals under energetic source suplementation, the daily average gain was 33.4% higher and those that consumed suplement with sorghum grain were the ones that showed higher daily average grain and higher pasture nutrients intake regarded to the animals that consumed corn grain. The fiber total aparent digestibilidty in neutral detergent corrected for ashes and protein was not affected by the suplementation, regardless to the energy source. Urinary ureic nitrogen level was lower in animals with no suplementation. Multiple suplements provided in quantity equal to 0.3% of the live weight promote weight gain higher to that obtained with mineral mixture in finishing crosbread steers in the rainy season. Fibrous or starch source formulated suplements provide a similar yield performance.

Efeito dos níveis de fibra em detergente neutro oriunda da forragem sobre a eficiência microbiana e os parâmetros digestivos em cabras leiteiras

The objective of this study was to evaluate the effect of diets with different neutral detergent fiber levels derived from the forage (NDFf), on ruminal parameters (pH and ammonia) in dairy goats. Five non-lactating goats were used, with fistulae in the rumen. The animals were arranged in a 5 × 5 Latin square using the NDFf levels (19, 27, 35, 42 and 18%), as independent variables. The increase in the NDFf levels of the rations reduced linearly the coefficients of apparent digestibility of DM, OM, EE and NSC and affected the NDF digestibility coefficient quadratically. The coefficients of ruminal digestibility of DM, OM and NDF increased linearly with the variation in the NDFf levels. However, reduction was observed in the coefficient of intestinal digestibility of DM, OM, CP and NDF. The increase in the NDFf contents and the collection times influenced the ruminal pH, but the ruminal ammonia only affected by the collection times. The efficiency of microbial protein synthesis, when expressed in g/kg TDN, was influenced by the increase in NDFf levels, was best at the 29.57% NDFf level.

Influência do Plano Nutricional sobre o Desempenho de Bezerros Holandeses para Produção de Vitelos

The experiment was carried out with 20 intact Holsteins male calves, average live weight of 75 kg and 76 days old, to evaluate the performance and the economical viability to produce veal calves. The calves were fed diets containing 45, 60, 75 and 90% of concentrate. Diets were composed of coastcross hay, ground corn, soybean meal and mineral mixture, fed ad libitum. The experimental design was a complete randomized blocks, with four treatments and five replicates. Before the beginning of the experiment, all the animals were submitted to the same nursing system. The experimental period was different for each treatment, since the animals were slaughtered as they reached an average weight of 200 kg. The variance analyses for dry matter and crude protein intake and dry matter conversion showed no significant effect of the concentrate levels in the diets. However, the regression analyses showed a decreasing linear effect as the concentrate level for the neutral detergent fiber intake increased, and a linear increase in the average daily gain, reducing in 35 days of feedlot for the animals fed 90% of concentrate. Significant effects due to the concentrate level were also observed for neutral detergent fiber and crude protein feed:gain ratio, and the improvement of the feed efficiency occurred as the concentrate level in the diet increased. The production costs analysis showed the viability to produce veal calves from Holstein bull calves.

Consumo, digestibilidade e estimativa do valor energético de alguns volumosos por meio da composição química

Intake, digestibility and energetic value estimates of feedstuff through chemical composition Nutrient intake, apparent digestibility and total digestible nutrients (TDN) levels of sugar cane, elephant grass silage, corn silage and sorghum silage were evaluated in sheep. The TDN values of feeds were also estimated with the equations proposed by NRC (2001). Twenty male castrated rams, housed in individual pens, were distributed in a randomized design in four treatments (feedstuffs) and five repetitions (animals). Nutrient apparent digestibility was determined by using total collection of feces. To compare predicted TDN values with in vivo TDN values, data were adjusted to a linear regression model. Sheep fed with the silages consumed larger amounts (P 0.05) for TDN intake among silages. The apparent digestibility of the dry matter (DM), organic matter (OM), crude protein (CP), ethereal extract (EE) and neutral detergent fiber (NDF) did not differ (P > 0.05) among treatments. There was difference (P < 0.05) between predicted and in vivo values of TDN. The equations proposed by NRC (2001) were not suitable to predict energetic value of tropical forages.