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O presente trabalho teve como principal objetivo o estudo das diferenças entre os resultados obtidos com o uso do método dos mínimos quadrados ponderados e de mínimos quadrados ordinários, no ajuste do modelo de Orskov e McDonald (1979) aos dados de degradação da matéria seca (MS) e fibra em detergente ácido (FDA) em novilhos Nelore fistulados, utilizando a técnica in situ. Foram utilizados os dados de um experimento delineado em quadrado latino 4x4 (quatro animais e quatro períodos) cujos tratamentos foram: dieta com sal de cálcio de ácidos graxos e monensina (A); dieta com caroço de algodão e monensina (B); dieta controle com monensina (C) e dieta com caroço de algodão sem monensina (D). As medidas de degradabilidade foram coletadas em oito ocasiões (0, 3, 6, 12, 24, 48, 72 e 96 horas). Como essas medidas são obtidas repetidamente no mesmo animal, espera-se que as variâncias das respostas nas diversas ocasiões não sejam iguais. Nas análises propostas foram utilizados os dados originais (MS e FDA) e os dados corrigidos para os efeitos de animal e de período. De uma forma geral, observou-se que o uso do método dos mínimos quadrados ponderados alterou os resultados das análises, produzindo um aumento das estatísticas dos testes e uma alteração da significância dessas estatísticas, por conta da retirada do efeito de animal e período dos dados originais e ao uso do método de mínimos quadrados ponderados, com a ponderação feita pelo inverso da variância dos dados em cada ocasião. / The present work had as main objective the study of the differences between the results obtained using the method of the weighted least squares and ordinary least squares, in the fit of the model of Orskov and McDonald (1979) to the data of degradation of the dry matter (MS) and acid detergent fiber (ADF) in fistulated Nelore steers, using the technique in situ. The data of a delineated 4x4 Latin Square had been used (four animals and four periods) whose treatments had been: diet with calcium salt of fatty acid and monensin (A); diet with whole cottonseed and monensin (B); diet has control with monensin (C) and diet with whole cottonseed without monensin (D). The measures of degradability had been collected in eight occasions (0, 3, 6, 12, 24, 48, 72 and 96 hours). As these measures they are gotten repeatedly in the same animal, expects that the variances of the answers in the diverse occasions are not equal. In the analyses proposals the original data (MS and ADF) and the data corrected for the period and animal effect had been used. Of a general form, it was observed that the use of the method of the weighted least squares modified the results of the analyses, producing an increase of the statisticians of the tests and an alteration of the significance of these statisticians, for account of the withdrawal of the animal effect and period of the original data and to the use of the method of weighted least squares, with the weighted made for the inverse one of the variance of the given ones in each occasion.

Objetivou-se avaliar a utilização de diferentes aditivos na alimentação de vacas em lactação sobre o consumo e digestibilidade aparente total da matéria seca e nutrientes, fermentação ruminal, produção e composição do leite, perfil metabólico e balanço de nitrogênio. Foram utilizadas 24 vacas da raça Holandesa, sendo destas 8 canuladas no rúmen, com média de produção de leite de 31,44 ± 4,83 kg, peso corporal médio de 586,07 ± 79,63 kg e com 175,89 ± 99,74 dias de lactação no início do fornecimento das dietas experimentais. Distribuídas em seis quadrados latinos 4x4, contemporâneos e balanceados, para receber as seguintes dietas experimentais: 1) Controle (CT), composta por dieta basal sem a inclusão de aditivos; 2) Crina (CRI) (Crina&reg; Ruminants, DSM-TORTUGA) , produto composto por uma mistura de óleos essenciais, sendo utilizado 1 g/vaca/dia; 3) Quitosana (QUI), com inclusão de quitosana na ordem de 150 mg/kg de peso vivo; 4) (MON) (Monensina DSM-TORTUGA), com inclusão de monensina na dose 24 mg/kg de matéria seca. Não foram observadas diferenças (P&lt;0,05) entre os tratamentos para consumo de matéria seca e nutrientes. Para digestibilidade da matéria seca e matéria orgânica a dieta QUI apresentou maiores valores (P<0,05) quando comparados a CRI. Em relação à digestibilidade da proteína bruta, a dieta com Crina foi menor (P<0,05) em relação aos demais aditivos. Não foram observadas diferenças (P<0,05) para produção e composição do leite entre as dietas experimentais. Os consumos de energia digestível e metabolizável foram maiores para os animais suplementados com quitosana em relação as dietas CO e MON. As eficiências da utilização de energia foram superiores para CO em relação a dieta com quitosana. A inclusão de monensina aumentou o colesterol total sérico em comparação a dieta controle. A excreção de nitrogênio fecal (g/dia), foi menor para CRI em relação aos demais aditivos, para % nitrogênio fecal total foi observada redução em relação a dieta com a adição de quitosana apenas. O balanço de nitrogênio em (g/dia) este foi maior para QUI, em relação MO. Quanto aos parâmetros fermentativos a inclusão de monensina e quitosana nas dietas reduziu a concentração de acetato (mmol/L), e a dieta CRI, aumentou ainda a concentração de propionato em mmol/L. Para a concentração de butirato, em mmol/L, a inclusão de monensina reduziu a concentração desta variável em relação à dieta controle, já os AGCR em mmol/L, todos os aditivos demonstraram efeito de redução (P<0,05), em relação à dieta controle. Para a concentração total de ácidos graxos de cadeia curta (mmol/L), as dietas com inclusão de Crina e monensina mostraram redução desta variável em relação à dieta controle. Assim, é possível concluir que quanto aos óleos essenciais (Crina Ruminants), as respostas não foram positivas para as variáveis avaliadas, possivelmente ocasionada pela intensa atividade antimicrobiana, não seletiva apenas aos microrganismos desejados, levando a efeitos desfavoráveis, entretanto a utilização de quitosana na alimentação de vacas leiteiras apresentam resultados semelhantes à utilização de monensina sódica ou superiores a dieta controle dependendo das variáveis a serem avaliadas, e pode ser uma grande alternativa na nutrição destes animais / The objective of this study was to evaluate the effects of different additives in dairy cows feeding on nutrient intake, total apparent digestibility of dry matter and nutrients, ruminal fermentation, milk yield and composition, concentrations of blood parameters and energy and nitrogen balances; 24 Holstein cows 31.44 ± 4.83 kg/day of milk yield, 586.07 ± 79.63 kg of BW and 175.89 ± 99.74 days in milk; mean ± SD), 16 intact and 8 ruminally fistulated. The animals were randomly assigned in six 4 x 4 Latin-square (contemporaneous and balanced) design to receive one of following diets: 1) Control (CO), diet without inclusion of monensin, chitosan or essential oils; 2) Crina® (CRI), inclusion of the mixture of essential oils (Crina&reg; Ruminants - SM Nutritional products TORTUGA) at 1g/cow/day; 3) Chitosan (QUI), inclusion of 150 mg/kg BW of chitosan, and; 4) Monensin (MON), inclusion of 24 mg/kg of diet DM of sodic monensin (DSM Monesin, TORTUGA). No differences in DMI and nutriente intakes were observed (P<0.05) for cows fed different treatments. Total apparent digestibility of DM and organic matter were higher for cows fed Q when compared to cows fed CR. The crude protein digestibility was decreased when cows were fed CR when compared to cows fed the diets containing other additives (M and Q). There were no differences (P<0.05) in milk yield and composition among cows fed experimental treatments. The intakes of digestible and metabolizable energy were higher for cows fed Q than cows fed C and M. The efficiency of energy utilization was higher for cows fed C when compared to cows fed Q. Monensin increased serum total cholesterol compared to C. The excretion of fecal nitrogen (g /day) was lower for the animals supplemented with CR compared to other additives to fecal nitrogen excretion (% of total nitrogen) differed just for animals fed Q. Cows fed Q had higher nitrogen balance than cows fed M. Experimental treatments did not alter pH, concentration of ruminal acetate (mmol / L) was decreased when cows were fed with M and Q, compared to C. Higher concentration of propionate (mmol / L) was observed for cows fed M than cows fed CR. Moreover, cows fed M had butyrate concentration (mmol / L) decreased compared to cows fed C, and short chain fatty acids concentration (mmol / L) was decreased when additives were added to diets. Total concentration of short chain fatty acids (mmol / L) was reduced when monensin and essential oils were added to the diet. Thus, we conclude that the essential oils (Crina Ruminants), responses were not positive for the variables evaluated, possibly caused by intense antimicrobial activity not only selective to the desired microorganisms, leading to adverse effects. However the use of chitosan in dairy cows have similar results of monensin use or above the control diet depending on the variables evaluated, and can be a great alternative nutrition of this animals

Três experimentos foram conduzidos com o objetivo de avaliar o efeito do óleo essencial de tomilho nos parâmetros ruminais, metabolismo e desempenho. O experimento I teve por objetivo avaliar se o óleo essencial de tomilho exerce efeito sofre a fermentação ruminal e consequentemente no metabolismo de ovinos confinados, bem como avaliar o consumo e digestibilidade aparente dos nutrientes em dietas com 90% concentrado e 10% de volumoso. Foram utilizados 20 ovinos ½ Dorper x ½ Santa Inês, machos castrados e canulados no rúmen. O experimento teve duração de 23 dias, dos quais 18 foram para adaptação as dietas. A ração base foi composta por feno de \"coastcross\", milho moído, farelo de soja, calcário calcítico, cloreto de amônia e mistura mineral. As dietas experimentais foram: 1) ração base + 25 mg de monensina por kg/MS, 2) ração base + 1,25 mL, 3) ração base + 2,50 mL e 4) 3,75 mL de óleo essencial de tomilho por kg/MS. O consumo de MS, MO, FDN e PB foram similares entre os tratamentos. Apresentando o mesmo comportamento para as variáveis de digestibilidade da MS, MO, FDN e PB. As concentrações de AGCC para as dietas com óleo essencial foram semelhantes à dieta com monensina. A inclusão de óleo essencial de tomilho nas dietas indica que este é uma potencial alternativa à monensina. O objetivo do experimento II foi avaliar se o óleo essencial de tomilho exerce efeito sofre a fermentação ruminal e consequentemente no metabolismo de ovinos confinados, bem como avaliar o consumo e digestibilidade aparente dos nutrientes em dietas com 80% volumoso e 20% concentrado. Foram utilizados 20 ovinos ½ Dorper x ½ Santa Inês, machos castrados e canulados no rúmen. O experimento teve duração de 28 dias, dos quais 23 foram para adaptação as dietas experimentais. A dieta base foi composta por pré secado de \"tifton\", milho moído, farelo de soja, calcário calcítico e mistura mineral. As dietas experimentais foram: 1) ração base + 25 mg de monensina por kg/MS, 2) ração base+ 1,25 mL, 3) ração base + 2,50 mL e 4) 3,75 mL de óleo essencial de tomilho por kg/MS. As dietas experimentais com óleos essencial apresentaram valores de consumo e digestibilidade da MS, MO, FDN e PB similares à dieta com monensina. A menor inclusão do óleo essencial apresentou valor de propionato e relação acetato:propionato similares à monensina. Houve interação dieta x dia de colheita para isobutirato, butirato, isovalerato e total de AGCC. A dieta com 1,25 mL de óleo apresentou o maior valor de pH. O óleo essencial de tomilho pode ser uma alternativa em substituição ao uso da Monensina. O objetivo do experimento III foi avaliar o óleo essencial de tomilho (Thymus vulgaris) sobre o ganho de peso e eficiência alimentar de borregas confinadas com dietas com alta inclusão de volumoso. Cinquenta borregas ½ Dorper x ½ Santa Inês, foram alojadas individualmente em baias cobertas. O período experimental foi de 84 dias, divididos em três sub-períodos de 28 dias. A dieta base foi composta por pré-secado de \"tifton\", milho moído, farelo de soja, calcário calcítico, mistura mineral. As dietas experimentais foram: 1) ração base (sem adição de óleo essencial ou monensina); 2) ração base + 25 mg de monensina por kg/MS; 3) ração base + 1,25 mL; 4) ração base + 2,5 mL; 5) ração base + 3,75 mL de óleo essencial por kg/MS. Não houve diferença de GMD entre os tratamentos no período total. O segundo período apresentou o melhor desempenho dos animais. A infestação por coccidiose foi menor na dieta com Monensina. Os teores dos aditivos utilizados não apresentam melhora no desempenho de borregas alimentadas com alto teor de volumoso. No entanto, monensina foi capaz de controlar a coccidiose. / Three experiments were conducted with the objective of evaluate the effect of thyme essential oil on ruminal fermentation, metabolism and performance. The experiment I was conducted to evaluate the thyme essential oil has an effect on ruminal fermentation and consequently the metabolism of feedlot sheep, as well as evaluate the intake and apparent digestibility of nutrients diets with 90% concentrate and 10% forage. They were used 20 sheep ½ Dorper x ½ Santa Inês, castrated males and fistulated in the rumen. The experiment lasted 23 days, of which 18 were for adaptation diets. The basal ration consisted of hay coast cross, ground corn, soybean meal, limestone, of ammonia chloride and mineral mixture. The experimental diets were: 1) basal ration + 25 mg of monensin per kg/DM, 2) basal ration + 1.25 mL, 3) basal ration + 2.50 mL and 4) basal ration + 3.75 mL of essential oil of thyme per kg/DM. The intake and digestibility of DM, OM, NDF and CP were similar between treatments. The SCFA concentrations for diets with essential oil were similar to the diet with monensina. The inclusion of thyme essential oil in diets that this is a potential alternative to monensina. The experiment II was conducted to evaluate the thyme essential oil has an effect on ruminal fermentation and consequently the metabolism of feedlot sheep, as well as evaluate the intake and apparent digestibility of nutrients diets with 80 % forage and 20% concentrate. They were used 20 sheep ½ Dorper x ½ Santa Inês, castrated males and fistulated in the rumen. The experiment lasted 28 days, of which 23 were for adaptation diets. The basal ration consisted of pre-dryng Tifton, ground corn, soybean meal, limestone and mineral mixture. The experimental diets were: 1) basal ration + 25 mg of monensin per kg/DM, 2) basal ration + 1.25 mL, 3) basal ration + 2.50 mL and 4) basal ration + 3.75 mL of essential oil of thyme per kg/DM. The intake and digestibility of DM, OM, NDF and CP were similar between treatments. The lower inclusion of essential oil showed a value propionate and acetate: propionate ratio similar monensin. There were diet x day interaction for isobutyrate, butyrate, isovalerate and the total SCFA. The diet with 1.25 mL of thyme showed the highest pH value. The thyme essential oil can be an alternative to replace the use of monensina. The experiment III was conducted to evaluate the thyme essential oil on weight gain and feed efficiency of feedlot lambs diets with 80% forage and 20% concentrate. Fifty lambs ½ Dorper x ½ Santa Inês were housed individually in covered bays. The experiment lasted 84 days, divided into three sub-periods of 28 days. The basal ration consisted of pre-dryng Tifton, ground corn, soybean meal, limestone and mineral mixture. The experimental diets were: 1) basal ration + 25 mg of monensin per kg/DM, 2) basal ration + 1.25 mL, 3) basal ration + 2.50 mL and 4) basal ration + 3.75 mL of essential oil of thyme per kg/DM. There was no gain difference in average daily gain between treatments in the total period. The second period had the best performance of the animals. Infestation by coccidiosis was lower in the diet with monensina. The levels of the additives used not showed improvement in performance lambs fed with high content of forage. However, monensin was able to control coccidiosis.

Orientadora: Jane Maria Bertocco Ezequiel / Banca: Luis Roberto de Andrade Rodrigues / Banca: Raul Franzolin Neto / Banca: Leandro das Dores Ferreira da Silva / Banca: Geraldo Maria da Cruz / Resumo: Este trabalho objetivou desenvolver uma metodologia "in vitro" simples e de baixo custo para avaliação da produção total de gás e proporções de metano, dióxido de carbono, oxigênio e nitrogênio presentes no mesmo, oriundos do processo fermentativo do líquido ruminal de bovinos. Foram avaliados os efeitos de três relações volumoso:concentrado (70, 50 ou 30% de volumoso, na matéria seca) e de duas qualidades de feno de capim-coastcross (Cynodon dactylon L. Pers., cultivar coastcross) sobre a produção de metano, dióxido de carbono e oxigênio. Foram avaliados também os efeitos da adição do volumoso, do concentrado, da mistura volumoso+concentrado e de cada componente do concentrado (milho, casca do grão de soja ou farelo de girassol) sobre a produção destes gases dentro de cada tratamento experimental. O tempo de fermentação foi de doze horas e as medidas das produções de gases (em mL) foram efetuadas em gasômetros especialmente projetados. As análises dos gases foram efetuadas em cromatógrafo gasoso. As rações com maiores porcentagens de concentrado e o volumoso de melhor qualidade nutricional resultaram em maiores produções de gás "in vitro". As rações com maiores porcentagens de volumoso e o volumoso de pior qualidade nutricional resultaram em produções de gás "in vitro" com maiores proporções de metano e de oxigênio e menores de dióxido de carbono. O aumento da porcentagem de concentrados na ração resultou em maiores produções de metano e de dióxido de carbono e menor de oxigênio. O ingrediente milho foi o que resultou em maiores produções médias de metano e de dióxido de carbono, seguido, em ordem decrescente, pelo farelo de girassol e pela casca do grão de soja. / Abstract: This work was conducted to develop a simple ïn vitro" methodology of low cost to evaluate the total production of gas and methane, carbon dioxide, oxygen, and nitrogen proportions, originated from fermentative process of rumen- liquid. The effects of three roughage:concentrated relations (70, 50 or 30% of roughage, in dry matter basis) and of coastcross grass (Cynodon dactylon L. Pers.) hay of two qualities, on the production of methane, carbon dioxide, and oxygen. The effects of the rumen-liquid mixed with the roughage, the concentrate, the roughage+concentrate mixture, and each component (grain corn, soybean seed coats and sunflower meal) of the concentrate on the production of these gases using the rumen fluid of each experimental treatment were also evaluated. The substrates were fermented by twelve hours and the gas production (in mL) was measured in gasometers especially projected for this purpose. The gas analyses were accomplished by gas chromatography. The diets with higher percentages of concentrate and the roughage with higher nutritional quality showed higher "in vitro" production of gas. The diets with higher quality roughage and lower nutritional quality showed in "in vitro" production of gas with higher proportion of methane and oxygen and with lower proportion of carbon dioxide. The increase of the concentrate percent in the diet resulted in higher productions of methane and carbon dioxide and lower production of oxygen. Grains of corn resulted in higher average productions of methane and carbon dioxide followed, in decreasing order, by sunflower meal and soybean seed coats. / Doutor

Esse trabalho foi conduzido com o objetivo de avaliar os efeitos da inclusão de óleo de soja ou de teores de caroço de algodão (CA) em dietas contendo alto teor de concentrado para bovinos confinados. No experimento I foram utilizados seis bovinos machos, castrados, da raça Nelore (407 &#177; 24 kg de peso corporal), distribuídos em um delineamento em Quadrado Latino 6 x 6. Foram avaliados 5 teores de inclusão (0, 8, 16, 24 e 32%) de CA em dietas contendo 80% de concentrado (tratamentos CA0, CA8, CA16, CA24 e CA32, respectivamente). Além disso, foi avaliada uma dieta contendo o mesmo teor de lipídios totais da dieta CA32, porém sem a inclusão de caroço de algodão, utilizando óleo de soja (tratamento OS). A inclusão de caroço de algodão na dieta reduziu (efeito linear, P &lt; 0,01) o consumo de matéria seca e o consumo de matéria orgânica dos animais. A digestibilidade aparente total da MS (P &#61; 0,019) e da MO (P &#61; 0,020) reduziu linearmente devido à inclusão de CA na dieta dos animais. A inclusão de óleo de soja na dieta não afetou o digestibilidade da MS (P &#61; 0,462) e da MO (P &#61; 0,469) dos animais em comparação aos animais alimentados com a dieta controle, sem CA, assim como também não foram observados efeito da fonte de lipídios sobre a digestibilidade da MS (P &#61; 0,124) e da MO (P &#61; 0,110). O tempo de ruminação aumentou linearmente (P &#61; 0,002) em resposta a inclusão de CA. O pH ruminal dos animais aumentou (efeito quadrático, P &lt; 0,05) em resposta à inclusão de caroço de algodão nas dietas. O inclusão de óleo de soja na dieta não afetou (P &#61; 0,329) o pH ruminal dos animais em comparação com a dieta controle sem CA. A produção total de ácidos graxos de cadeia curta reduziu (P &lt; 0,001; efeito linear) devido à inclusão de CA. A síntese de Pmic reduziu linearmente (P &#61; 0,011) em resposta a inclusão de CA na dieta. No experimento II, foram utilizados 280 bovinos machos, da raça Nelore e peso médio inicial de 349 &#177; 33 kg, distribuídos em 40 baias. O delineamento utilizado foi blocos incompletos casualizados. O máximo peso final foi obtido com inclusões de 7,6% de CA. A inclusão de CA na dieta reduziu o CMS dos animais (P &lt; 0,001). A inclusão de óleo de soja reduziu o CMS dos animais (P &lt; 0,05) em comparação com os animais alimentados com a dieta controle sem caroço de algodão. O máximo GPD foi observado com 8% de inclusão de CA na dieta. A máxima EA ocorreu com 14,5% de CA na dieta. Os dados referentes as característica da carcaça (PQC, RC, AOL e EGS) também apresentaram resposta quadrática (P &lt; 0,05) à inclusão de CA na dieta. Comparado ao tratamento controle, sem CA na dieta, a inclusão de óleo de soja não afetou nenhuma das características da carcaça avaliadas (P &gt; 0,05). As características químicas da carne não diferiram (P &gt; 0,05) entre os animais alimentados com dietas contendo 32% de CA daqueles alimentados com óleo de soja. A oxidação dos lipídios (TBARS) apresentou redução (efeito quadrático; P &#61; 0,035) devido à inclusão de CA na dieta. Na avaliação sensorial da carne assada realizada através do painel consumidor, não foram observados efeitos dos tratamentos sobre o sabor, odor e aceitabilidade geral da carne (P &gt; 0,05). Na avaliação das características organolépticas da carne realizada pelos provadores treinados também não foram observados efeitos dos tratamentos sobre o odor, sabor e aceitabilidade geral (P &gt; 0,05). No experimento III, avaliou-se a cinética de fermentação ruminal do milho e do caroço de algodão através da produção cumulativa de gases. Foram utilizados cinco frascos (repetições) contendo 1g de substrato (milho ou CA) além de 5 frascos &ldquo;brancos&rdquo; (sem substrato). As leituras de pressão e volume dos gases acumulados nos frascos de incubação foram realizadas com transdutor de pressão nos tempos 0, 2, 4, 6, 8, 10, 12, 15, 19, 24, 30, 36, 48, 72 e 96 horas. O milho apresentou um maior potencial de produção de gases quando comparado ao caroço de algodão (P &lt; 0,001). O tempo de colonização não apresentou diferença entre as duas fontes de energia (P &#61; 0,646). O caroço de algodão apresentou uma maior taxa de degradação comparado com o milho (P &#61; 0,001) e, consequentemente, para a redução (P &lt; 0,001) do tempo necessário para atingir a máxima produção de gás. O milho apresentou uma maior potencial de degradação quando comparado com o caroço de algodão, resultado esse que pode ser observado pelo maior produção de gases. Apesar não suportar um grande potencial de degradação, parte da fração fribrosa do caroço de algodão apresentou alta degradabilidade, o que pode ser observado na sua maior taxa de degradação quando comparado com o milho / Three trials were conducted to evaluate the effects of the inclusion of levels of whole cottonseed (WC) or soybean oil (SO) in diets for Nellore feedlot cattle. In the experiment I six rumen-cannulated Nellore steers (407 &#177; 24 kg BW) were used in a 6 x 6 Latin square design experiment. Were evaluated 5 levels of inclusion of WC (0, 8, 16, 24 and 32% DM basis) in diets containing 87% concentrate (treatments WC0, WC 8, WC16, WC24 and WC32 respectively). Also, it was evaluated a diet containing the same amount of total fat content of WC32 but with no WC and using soybean oil (SO treatment). Increasing WC levels linearly decreased DM and OM intake (P &lt; 0.01). CP and NDF intakes were not affected by the treatments. Total fat digestibility linearly increased due the WC increase in the diets (P &lt; 0.001). Total DM (P &#61; 0.019) and OM (P &#61; 0.020) digestibilities linearly decreased with increasing levels of WC. SO inclusion did not affect DM (P &#61; 0.462) and OM (P &#61; 0,469) digestibilities compared with CA0 and there was no effect of fat source over DM (P &#61; 0.124) and OM (P &#61; 0.110) digestibilities. Rumination time linearly increased due the WC inclusion (P &#61; 0,002). Increasing WC levels quadratically increased ruminal pH (P &lt; 0.05) but no effect was observed with the SO addiction in the diet (P &#61; 0.329) compared with CA0. Total VFA was linearly decreased with increasing levels of WC (P &lt; 0.001). Increasing levels of WC linearly decreased the microbial protein synthesis (P &#61; 0.011). In the experiment II a total of 280 Nellore bulls (initial BW &#61; 349 &#177; 33 kg) were allotted in 40 pens. The statistical design was randomized incomplete blocks. The maximum final BW was obtained with 7.6% of inclusion of WC. Increasing levels of WC decreased DMI (P &lt; 0.001). Adding SO also decreased DMI (P &lt; 0.05) compared with WC0. Increasing the inclusion rate of WC quadractically increased the ADG, G:F, HCW, dressing percent, LM area and 12-rib fat (P &lt; 0.05). The maximum ADG were obtained with 8% of inclusion of WC. On the other hand, the maximum G:F was obtained with 14.5% of WC. Compared with WC0, the SO inclusion did not affect carcass characteristics (P &gt; 0.05). The inclusion of WC quadractically affect meat composition (P &lt; 0.05). Compared with CA32, the inclusion of SO in the diet did not affect the meat composition. Increasing WC in the diets quadratically decrease (P &#61; 0.035) lipid oxidation. No effects were observed in the sensorial evaluation flavor, taste and overall acceptability by the costumers (P &gt; 0.05). Training sensory panelists also did not find differences between the treatments for flavor and taste. Increasing WC linearly decreased the tenderness (P &#61; 0.045). Compared with CA32, the inclusion of SO increased meat tenderness (P &#61; 0.031). In the experiment III was evaluated the ruminal fermentation kinetics of corn and cottonseed through the in vitro gas production technique. Five bottles for each energy source (corn and cottonseed), plus five additional bottles containing buffered medium and rumen fluid inoculum only (blanks) were used. The volume of gas produced was recorded at 0, 2, 4, 6, 8, 10, 12, 15, 19, 24, 30, 36, 48, 72 e 96 h of incubation using the pressure reading technique. Gas values were corrected for blank incubations. The corn had greater gas production than cottonseed (P &lt; 0.001). Lag time was not different between the two energy sources (P &#61; 0.646). Cottonseed had higher FDR than corn (P &#61; 0.001) and shorter time to half asymptote (P &lt; 0.001). Corn had higher potential of degradation compared with cottonseed observed by the higher gas production. Moreover, even with lower potential of degradation, the cottonseed fibrous fraction had a high degradability compared to corn

Orientador: Telma Teresinha Berchielli / Coorientador: Roberta Carrilho Canesin / Banca: Márcia Helena Machado da Rocha Fernandes / Banca: Ricardo Andrade Reis / Banca: Otávio Rodrigues Machado Neto / Banca: Maria Fernanda Soares Queiroz / Resumo: Objetivou-se com este estudo caracterizar as alterações na microbiota ruminal, parâmetros ruminais, consumo, digestibilidade das dietas e a eficiência de síntese microbiana, em novilhos Nelore confinados alimentados com diferentes relações volumoso:concentrado, utilizando como fontes de volumoso o feno de Tifton 85 ou cana-de-açúcar. Foram realizados dois experimentos, no experimento 1 utilizou a cana-de-açúcar como fonte de volumoso e no experimento 2 utilizou-se o feno de tifton 85 como volumoso. Em ambos os experimentos foram testadas diferentes relações V:C (70:30; 60:40; 40:60 e 20:80). Em cada experimento, utilizaram-se oito novilhos Nelore (331±8 kg PV), cânulados no rumen, distribuídos em duplo quadrado latino 4x4 balanceados para o controle do efeito residual. No experimento 1 (cana-de-açúcar), o aumento da proporção de concentrado na dieta reduziu a população de Fibrobacter succinogenes e Ruminococus flavefaciens, e aumentou a população de Selenomonas ruminantium e Megasphaera elsdenii, porém o CDFDN não foi alterado. O aumento da participação de carboidratos não estruturais na dieta favoreceu a síntese de proteína microbiana e reduziu a população de bactérias fibrolíticas. A cana-de-açúcar como fonte de volumoso em dieta com proporções crescente de concentrado pode otimizar a síntese de proteína microbiana sem alterar digestibilidade da fibra. No experimento 2 (feno de Tifton 85), o aumento da proporção de concentrado na dieta reduziu a população de Fibrobacter succinogenes, Ruminococus flavefaciens e Ruminococcus albus e aumentou a população de Selenomonas ruminantium e Megasphaera elsdenii e Streptococcus bovis e o CDFDN diminuiu com o aumento da proporção de concentrado na dieta. Feno de Tifton 85 em dietas com altas proporções de concentrado pode minimizar o risco de distúrbios ruminais em novilhos confinados / Abstract: This trial aimed to characterize the changes in ruminal microbiota, ruminal fermentation, intake, diet digestibility and microbial efficiency in Nellore steers fed with different forage:concentrate proportions, using as sources of forage Tifton 85 hay or sugar cane. Two experiments were conducted: in experiment 1 the sugar cane was used as forage source and in Experiment 2 the Tifton 85 hay was used as forage source. In both experiments were tested different F:C proportions (70:30, 60:40, 40:60 and 20:80). On each experiment were usedeight Nellore steers ( 331 ± 8 kg BW) cannulated in the rumen, in a double latin square 4x4 balanced to control the residual effect. In experiment 1 (sugar cane), increasing the proportion of concentrate in the diet reduced the population of Fibrobacter succinogenes and Ruminococus flavefaciens, and increased the population of Selenomonas ruminantium and Megasphaera elsdenii, but the digestibility of NDF has not changed. The increased participation of non-structural carbohydrates in the diet favored microbial protein synthesis and reduced the population of fibrolytic bacteria. The use of sugar cane as forage source associated with the increases of concentrate proportions in the diet can optimize microbial protein synthesis without change the fiber digestibility. In experiment 2 (Tifton 85 hay), increasing the proportion of concentrate in the diet reduced the population of Fibrobacter succinogenes, Ruminococcus albus and Ruminococus flavefaciens and increased the population of Selenomonas ruminantium, Megasphaera elsdenii and Streptococcus bovis and the digestibility of NDF decreased when increases the proportion of concentrate in the diet. Tifton 85 hay in diets with high proportions of concentrate can minimize the risk of ruminal disorders in feedlot steers / Doutor

Transitioning cattle from a high-forage to a high-concentrate diet increases the risk for ruminal acidosis and is often related to decreased feed intake, which compromises animal health and performance. Since control of feed intake and rumen motility are closely related, we hypothesized that a reduction in rumen motility may be associated with a reduction in feed intake during this transition. Computer programs were created to analyze feed disappearance and rumen pressure data for feeding behavior as well as identification and characterization of rumen contractions, respectively. This method enabled timely analysis of large datasets and removed subjectivity associated with manual analysis. In the second part of this series, cattle were moderately transitioned from a 70% to a 90% concentrate diet, and SARA was induced. Although, reductions in feed intake were modest, on day 2 of high-grain feeding, animals slowed feed consumption rate and displayed a reduction in rumen contraction frequency, amplitude, and duration. Next, an abrupt transition from 50% to 90% concentrate was used to induce ruminal acidosis and cause some animals to stop eating. The abrupt increase in dietary concentrate was also associated with reductions in rumen motility. Patterns of ruminal pH, viscosity, and motility changes were related to when cattle reduced feed intake. Endotoxin quantification in blood samples from the ruminal vein, portal vein, and mesenteric artery suggested the point of endotoxin translocation into blood was across the ruminal epithelium. Additionally, the greater the concentration of endotoxin in the plasma, the more likely animals were to go “off-feed.” By understanding the physiological and behavioral mechanisms by which cattle adapt to high-grain diets, we can improve animal health and performance through these diet transitions.

Barley, cornstarch, crested wheatgrass, glucose, molasses and solka floc were fermented with rumen fluid obtained from sheep that were adapted or unadapted to feed grade biuret (Kedlor) in their diet. Each rumen fluid and substrate combination was subjected to three nitrogen treatments: (1) control, (2) nitrogen added as feed grade biuret and (3) reagent grade biuret in a factoral arrangement of treatments. In vitro fermentations were terminated at 0, 12, 24, and 36 hours and the protein nitrogen insoluble in trichloroacetic acid (TCA) was determined. Molasses and cornstarch fermentation residues increased while barley, crested wheatgrass, glucose and solka floc decreased in TCA insoluble protein nitrogen. The average of all treatments decreased in TCA insoluble protein nitrogen during the first 12 hours and increased during the remaining 24 hours. Unadapted rumen fluid with simple carbohydrates from glucose and molasses and adapted rumen fluid with complex carbohydrates from barley, crested wheatgrass, cornstarch and solka floc gave the largest gains in TCA insoluble protein nitrogen. No significant differences occurred due to the addition of non-protein nitrogen.

Transactions of magnesium (Mg) along the gastrointestinal tract and the effect of change in potassium (K) intake were recorded in two in vivo experiments in sheep and cattle. Additional information on the sensitivity to K intake was obtained by comparing Mg transport and electrochemical properties of isolated rumen epithelia of sheep and cattle in 4 additional in vitro experiments. The experiment described in Chapter 2, and performed in sheep housed indoors in metabolic crates, investigated the compensatory capacity of the intestine to respond to the reduction in Mg absorption from the stomach as a consequence of increase in K intake. The animals were equipped with a ruminal cannula and two intestinal cannulae (duodenum and ileum) and flow of digesta was measured by the addition of two indigestible markers, chromium ethylenediaminetetra-acetic acid (Cr-EDTA) and ytterbium acetate (Yb). The animals were infused in a Latin square design for periods of 10 days with a solution of K bicarbonate that provided between 15 and 47 g of K/day. The diet consisted of a 50:50 combination of concentrates plus lucerne hay that provided around 3.7 g of Mg per day and 15 g of K per day. After 5 days of infusion samples of feed, faeces, urine and plasma were collected and analysed for Mg and K content. After 6 days of infusion, samples of duodenal and ileal flow were obtained. The treatments reproduced the detrimental effect of K on Mg absorption, especially in the rumen; a rise in K intake from 15 to 23 g/day reduced total Mg absorption from the gastrointestinal tract from 1.36 to 1.23 g/day, further increase in K intake to 38 and 47 g/day reduced absorption to 1.12 and 1.05 g/day, an overall reduction of around 50% in Mg apparent availability. Magnesium was mainly absorbed in the stomachs and large intestine with the small intestine a site of net secretion. Most of the reduction in Mg absorption with increase in K intake occurred in the stomachs, reducing from 1.86 to 1.11 g/day. A compensatory reduction in the net secretion of Mg from the intestines (small and large) was observed. This compensation was largely due to reduction in net secretion from the small intestine, from 0.85 to 0.22 g/day, rather than an increase in net absorption from the large intestine, although both segments acted synergistically. Results also suggested significant individual variation in plasma Mg concentration, urinary Mg excretion and in the flow and absorption of Mg along the gastrointestinal tract. It was suggested that most of that variability was due to genetic factors. Differences between species (cattle and sheep) were pursued during the course of the experiment described in Chapter three. Four triple cannulated rams and 3 triple cannulated dry cows were placed in metabolic crates, fed daily fresh-cut pasture and infused, in a total randomised design that provided the equivalent of an intake of 30,40 and 50 g of K per kg dry matter intake (DMI) per day. Solutions of K (as K bicarbonate) and markers (CrEDT A and Yb acetate) were infused continuously for a period of 10 days; after 5 days of infusion samples of pasture, faeces, urine and plasma were collected and analysed for Mg and K content. After 6 days of infusion, samples of duodenal and ileal flow were obtained. Total feed offered, refusals and water consumption were recorded daily. Results showed a greater sensitivity of cattle to the increase in K supply. A rise in K supply from 30 to 40 g per kg DMI/day reduced Mg absorption by almost 50% from 0.32 to 0.16 g per kg DMI/day, whereas only the highest treatment dose (50 g of K per kg DMI/day) produced the same deleterious effect in sheep. The absorption of Mg occurred mainly in the stomachs and large intestine; in contrast the small intestine was a site of net secretion in both species. The addition of K slightly reduced the rate of Mg absorption from the rumen, especially in cattle. Similarly, net Mg secretion within the intestines increased with increasing K intake in both species, only to be counterbalanced by a greater Mg absorption from the large intestine. The large intestine in both species (sheep and cattle) reduced faecal losses of Mg but was unable to fully compensate for the reduction in Mg absorption from the stomach or the greater net Mg secretion observed at the small intestine. Differences between species in water content of the faeces were observed to be mainly related to the moisture content of the digesta that reached the ileum rather than a result of differences in absorption in the large intestine. More evidence of species differences in Mg transport and of sensitivity to K intake were obtained by using isolated rumen epithelia and the Ussing chamber technique. Transport and electrophysiological properties of the tissues were observed in standard conditions and by adding different K concentrations to the mucosal side. Under standard conditions and open-circuit voltage, sheep isolated rumen epithelia had greater transmural potential difference (PDt), and lower conductance (Gt) but similar short-circuit current (Isc) than those from cattle. These results suggested that the rumen epithelium of cattle is leakier than that of sheep. Measurement of the transport of Mg showed that isolated rumen epithelia of cattle transported more Mg and was saturated at higher Mg concentrations (12 vs 4 mM) than sheep epithelia. These differences in Mg influx (transport from mucosa to serosa) were also observed in studies of Mg transport using stable isotopes. Magnesium influx (transport from mucosa to serosa) from the isolated rumen of cattle was greater than in sheep (57.5 ± 12.72 vs. 17.3 ± 12.72 nmol.cm⁻².h⁻¹); however this was counterbalanced by a greater Mg efflux (transport from serosa to mucosa) of 48.1 ± 12.72 vs. 9.9 ± 12.72 nmol.cm⁻².h⁻¹, for cattle and sheep respectively, when mucosal K concentrations were around 25 mM. A increase in K concentration on the mucosal side enhanced transmural potential difference (PDt) and short-circuit current (Isc) to a greater extent in sheep than in cattle, suggesting a greater effect of K on sheep than on cattle epithelia. On the other hand, the transport of Mg measured by stable isotopes suggested that net absorption of Mg (7.4 ± 12.72 vs. 11.1 ± 12.72 nmol.cm⁻².h⁻¹) in sheep epithelia was similar at 25 and 50 mM of K on the mucosal side, whereas net Mg influx in cattle was largely depressed as a consequence of a reduction in Mg influx (mucosa to serosa) from 57.7 ± 12.72 to 2.9 ± 12.72 nmol.cm⁻² h⁻¹ together with a constant Mg efflux (serosa to mucosa) 48.1 ± 12.72 and 41.2 ± 12.72 nmol.cm⁻².h⁻¹, presumably leaving through a paracellular shunt. However, this finding was based on date from a small size and caution should be applied to this conclusion. In conclusion, data collected from several comparative studies suggest differences in Mg apparent availability between sheep and cattle and also a greater sensitivity of cattle to an increase in K intake. This high sensitivity to K represents a great risk of hypomagnesaemia in dairy cattle in New Zealand where high K concentration is endemic in pastures. Most importantly, these results suggest that models for Mg metabolism in cattle should be based on measurements from cattle nutritional and physiological studies rather than on extrapolation from sheep studies.