Bacteria, belonging to the Lactobacillus bifidus group, were isolated from rectal swabs obtained from healthy babies receiving breast milk. The fermentation properties of these bacteria in cow's milk were studied. Strains potentially suitable for fermentation in a food product were selected according to their ability to produce lactic acid and no gas from lactose, as well as adhering to characteristics common to the bifidus group (Gram positive, catalase negative and blanching morphology). The five strains chosen for intensive study produced 1.14 to 1.25% lactic acid and less than 0.05% volatile acid. The latter organisms could be cultured readily and coagulated milk in less than 24 hr when using a 5% inoculum. Repeated subculture resulted in a change from the branched to the unbranched bacterial morphology. This transformation, which is not unusual among bifid bacteria, was accompanied by a change in ability to produce lactic acid, but no gas was produced by branched or unbranched strains. A great deal of variability in morphology, growth consistency, and acid production was observed among the more than 500 bacterial strains isolated. However, the bifid populations from Caucasian babies was not noticeably different from those of native Indian babies. All of the five strains selected utilized inulin, dextrin, mannitol, and melezitose. A 24 hr culture of fermented milk yielded a product with a mild pleasant natural flavour which could conceivably be altered, if desired, by adding sweeteners or flavouring agents / Land and Food Systems, Faculty of / Graduate

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Submitted by Lucelia Lucena (lucelia.lucena@ufpe.br) on 2015-03-10T18:06:55Z No. of bitstreams: 2 Gabriela Teixeira _ Dissertação Mestrado.pdf: 1514043 bytes, checksum: f74fa7770b03bc783658b45328e64e05 (MD5) license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) / Made available in DSpace on 2015-03-10T18:06:55Z (GMT). No. of bitstreams: 2 Gabriela Teixeira _ Dissertação Mestrado.pdf: 1514043 bytes, checksum: f74fa7770b03bc783658b45328e64e05 (MD5) license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Previous issue date: 2012-03 / A adição de culturas probióticas tem sido testada em vários produtos lácteos, e a maior parte dos microrganismos consegue permanecer viável, alcançando características desejáveis no produto final. O objetivo da pesquisa foi desenvolver requeijão cremoso com probióticos, Lactobacillus acidophilus e Bifidobacterium bifidum, a fim de se tornar uma alternativa saudável de um alimento de amplo consumo. Foram elaboradas 3 formulações: requeijão cremoso fresco padrão, requeijão cremoso fresco com probióticos, requeijão cremoso fresco probiótico com reduzido teor de gordura. Para a caracterização do produto foram realizadas análises para determinação da composição centesimal, em triplicata para determinação de umidade, cinzas, lipídios e proteínas, e carboidratos. A contagem de coliformes totais e Escherichia coli foram realizadas nas amostras para análise da qualidade higiênico-sanitária. Realizou-se a contagem de L. acidophilus e B. bifidum durante o período de armazenamento de 15 dias. A avaliação da resistência das culturas probióticas às condições digestivas foi realizada empregando-se um modelo in vitro, utilizando suco gástrico e entérico simulados e enzimas do trato gastrintestinal. A análise da cor foi realizada por colorimetria em escala CIELab. A análise sensorial foi aplicada pelo teste de aceitação por escala hedônica para avaliação dos atributos e avaliação da qualidade global e intenção de compra. A composição centesimal dos requeijões padrão e adicionado de probióticos atendeu aos requisitos da legislação para o produto. O requeijão proposto como light apresentou redução de 26% no valor calórico total e 43% no teor de lipídeos em relação ao padrão. Quanto a acidez titulável, observou-se que o armazenamento influenciou significativamente os seus valores nas preparações com probióticos, diferindo do padrão que não apresentou alterações nos valores durante o armazenamento. A qualidade higênico-sanitária foi satisfatória, visto que as amostras foram negativas para presença de coliformes totais e Escherichia coli. As contagens individuais de Lactobacillus acidophilus e Bifidobacterium bifidum, estiveram de acordo com as exigências da legislação para alimentos com alegações de propriedades funcionais. O requeijão cremoso fresco probiótico apresentou contagem de L. acidophilus de 4,0x107UFC/g e B. bifidum de 2,0x108UFC/g aos sete dias de armazenamento e o requeijão cremoso fresco probiótico com reduzido teor de gordura apresentou contagem de L. acidophilus de 5,0x109UFC/g e B. bifidum de 2,0x109UFC/g. A redução de gordura no produto até os níveis estudados não interferiu na viabilidade dos probióticos no requeijão cremoso durante o armazenamento de 15 dias. Após a simulação da digestão in vitro, houve redução da população total de probióticos em ambas as formulações com resultados mais expressivos para a formulação com reduzido teor de gordura afirmando o efeito protetor das gorduras para a sobrevivência dos probióticos ao trato gastrintestinal. A análise instrumental da cor dos requeijões cremosos indicou produtos com boa luminosidade, com acentuação da cor amarela ao longo do tempo de armazenamento. A avaliação sensorial demonstrou que a adição de probióticos resultaram em requeijões cremosos com melhor perfil de características e maior aceitabilidade e intenção de compra que a preparação padrão. Pode-se concluir que os probióticos melhoraram a qualidade sensorial do produto, sendo tais amostras preferidas pelos julgadores. O requeijão cremoso tradicional e com baixo teor de gordura são tecnologicamente viáveis para a incorporação das culturas probióticas de L. acidophilus e B. bifidum.

Made available in DSpace on 2017-07-10T17:48:20Z (GMT). No. of bitstreams: 1 Maikel_Possamai.pdf: 915835 bytes, checksum: b9f7340ba0b838b5bd95229abaed0be6 (MD5) Previous issue date: 2010-08-20 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Two experiments were conducted to evaluate the effect of using probiotics and symbiotic in piglets diets in the nursery phase. The first experiment was the performance of piglets from 21 to 35, from 36 to 49 days and in total period, being also held the count of lactic bacteria, fecal coliforms and clostridia in the piglets faeces at 35 and 49 days old. The economic viability of probiotics and symbiotic used in piglets diets was also evaluated. There were used 120 piglets, with 21 days old, with initial average weight of 5.80 ± 0.30 kg, distributed in a randomized blocks design, in a factorial scheme consisting of two levels of probiotics (0.30 and 0.60%) and three levels of inulin inclusion (0.00; 0.25 and 0.50%), totalizing six treatments with five replicates. In the metabolism trial were used 24 barrows, with average initial weight of 18.00 ± 0.38 kg, distributed individualy in metabolic cages, and the experimental design and treatments used were the same described in the performance experiment, with four replicates. In this trial were determined the values of digestible energy, metabolizable energy, the digestibility and metabolizability coefficients of gross energy and at the end of metabolism trial, were collected fecal samples, by means of retal massage to determine fecal pH. The inclusion of probiotic and inulin in the diets did not influence (P>0.05) the performance of piglets, from 21 to 35 and from 21 to 49 days of age, the cost index, the index of economic efficiency, the count of lactic bacteria, fecal coliforms and clostridia in the faeces. In the metabolism trial was observed that the inclusion of probiotics in the diets did not influence in the energy metabolization. Nevertheless, the levels of inclusion of inulin reduced (P<0.05) the digestible energy and the digestibility coefficient of gross energy, but did not influence in the coefficient of gross energy metabolization. The pH fecal values were not influenced by the inclusion of probiotic and symbiotic. The use of probiotic and inulin, and their association, did not change the performance, thefaeces microbial counts, the economic viability and gross energy metabolization of piglets from 21 to 49 days old / Foram realizados dois experimentos para avaliar o efeito do uso de probióticos e simbiótico em rações para leitões na fase de creche. O primeiro experimento foi o de desempenho dos leitões dos 21 aos 35, dos 36 aos 49 dias e no período total, sendo também realizada a contagem das bactérias lácticas, coliformes e clostrídios nas fezes dos leitões, aos 35 e 49 dias de idade. A viabilidade econômica da utilização dos probióticos e simbiótico nas rações dos leitões também foi avaliada. Foram utilizados 120 leitões, com 21 dias de idade, com peso médio inicial de 5,80 ± 0,30 kg, distribuídos em um delineamento experimental de blocos ao acaso, em um esquema fatorial constituído de dois níveis de probióticos (0,30 e 0,60%) e três níveis de inclusão de inulina (0,00; 0,25 e 0,50%), totalizando seis tratamentos com cinco repetições. No ensaio de metabolismo foram utilizados 24 suínos machos castrados, com peso vivo médio inicial de 18,00 ± 0,38 kg, distribuídos individualmente em gaiolas de metabolismo, e o delineamento experimental e tratamentos utilizados foram os mesmos descritos no experimento de desempenho, com quatro repetições. Foram determinados os valores de energia digestível, energia metabolizável, os coeficientes de digestibilidade e metabolizibilidade da energia bruta e no final do ensaio metabólico foram coletadas amostras de fezes, por meio de massagem retal, para determinar o pH fecal. A inclusão do probiótico e inulina nas rações não influenciou (P>0,05) o desempenho dos leitões, dos 21 aos 35 e dos 21 aos 49 dias de idade, o índice de custo, o índice de eficiência econômica, a contagem de bactérias acidoláticas, coliformes e clostrídios das fezes. No ensaio metabólico foi observado que a inclusão de probiótico nas rações não influenciou na metabolizibilidade da energia. No entanto, os níveis de inclusão de inulina reduziram (P<0,05) os valores de energia digestível e o coeficiente de digestibilidade da energia bruta, mas não influenciaram no coeficiente de metabolizibilidade da energia bruta. Os valores de pH fecal não foram influenciados pela inclusão de probiótico e simbiótico. O uso de probiótico e inulina, e sua associação, não alteraram o desempenho, a contagem de micro-organismos, a viabilidade econômica e a metabolizibilidade da energia bruta de leitões dos 21 aos 49 dias de idade

Made available in DSpace on 2017-07-10T17:48:24Z (GMT). No. of bitstreams: 1 Wagner_Thiago_Mozer_da_Silva.pdf: 197351 bytes, checksum: b4b84a219d2e39d9b19bb5c957000af1 (MD5) Previous issue date: 2010-08-23 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The objective of this work was evaluate the effect of different levels of inclusion of inulin (chicory root extract) in diets containing ingredients of plant and animal on performance, carcass characteristics (cuts and abdominal fat) and the parameters blood, for broiler chickens 10-40 days old. 1056 chicks were used from one day old, housed on reused litter in a completely randomized design with eight treatments and six replicates of 22 birds each, which were arranged in a factorial 2 x 4, where the first factor was the use of two diets (plant and animal) and the second factor represented by four levels of inulin (0.00, 0.25, 0.50, 0.75%). The probiotic used was composed of Lactobacillus acidophillus, Bifidobacterium bifidum and Streptococcus faecium. The characteristics evaluated were weight gain, final weight, average feed intake, feed conversion, viability 1-40 days of age. At 21 and 35 days of age were measured blood parameters (calcium, phosphorus, uric acid and total protein). At 40 days was carried out the slaughter of birds to assess the yield of carcass, breast, drumstick, thigh, wing and abdominal fat percentage. Within the analysis of economic viability was calculated the cost of the experimental diets, the index of economic efficiency and cost index. In the initial phase and growth was not found significant results for the performance variables. In the total periods of 1-40 days of age for the variable feed no significant effect (P <0.05) for levels of inclusion. Carcass yield was influenced (P <0.05) by food type regardless of the levels of inclusion of inulin. For the cuts, only the thigh showed a significant difference (P <0.05) for the type of diet. Was observed in abdominal fat interaction (P <0.05) between type of diet (plant and animal) and the levels of inclusion of inulin. For the blood parameters for 21 days was significantly different (P <0.05) between levels of inulin inclusion for the variables P and total protein, and 35 was again a significant difference (P <0.05) for phosphorus . The other variables were not affected with the use of inulin. The use of 2.5 g / kg inulin provides better feed for broilers at 1-40 days old. Inclusion of inulin reduces abdominal fat independent mind the type of diet. The use of feed containing animal ingredients provides improved higher carcass yield and higher thigh yield. The use of inulin affected the phosphorus stock you live at 21 and 35 days old. The use of inulin in diets of broiler feed cost rises mind independent of the use of ingredients of animal or vegetable / Objetivou-se com este trabalho avaliar o efeito de diferentes níveis de inclusão de inulina (extrato de raiz chicória) em rações contendo ingredientes de origem vegetal e animal, sobre o desempenho, as características de carcaça (cortes nobres e gordura abdominal) e os parâmetros sanguíneos, para frangos de corte de 1 a 40 dias de idade. Foram utilizados 1056 pintos de um dia de idade, alojados sobre cama reutilizada, em um delineamento experimental inteiramente casualizado, com oito tratamentos e seis repetições e 22 aves por unidade experimental, os quais foram arranjados em um esquema fatorial 2 x 4, onde o primeiro fator foi a utilização de duas dietas (vegetal e animal) e o segundo fator representado por quatro níveis de inclusão de inulina (0,00; 0,25; 0,50; 0,75%). O probiótico utilizado era composto por Lactobacillus acidophillus; Streptococcus faecium e Bifidobacterium bifidum. As características avaliadas foram ganho de peso, peso final, consumo médio de ração, conversão alimentar, viabilidade de 1 a 40 dias de idade. Aos 21 e 35 dias de idade foram mensurados os parâmetros sanguíneos (cálcio, fósforo, ácido úrico e proteínas totais). Aos 40 dias foi realizado o abate das aves para avaliar o rendimento de carcaça, peito, coxa, sobrecoxa, asa e percentual de gordura abdominal. Dentro da análise da viabilidade econômica foram calculados os custos das dietas experimentais, o índice de eficiência econômica e o índice de custo. Na fase inicial e de crescimento não foi encontrado resultado significativo para as variáveis de desempenho. No período total de criação de 1 a 40 dias de idade, para a variável conversão alimentar houve efeito significativo (P<0,05) para os níveis de inclusão. O rendimento de carcaça foi influenciado (P<0,05) pelo tipo de ração independente dos níveis de inclusão de inulina. Para os cortes, somente a coxa apresentou diferença significativa (P<0,05) para o tipo de ração. Na gordura abdominal foi observado interação (P<0,05) entre o tipo de ração (vegetal e animal) e os níveis de inclusão de inulina. Para os parâmetros sanguíneos aos 21 dias foi observada diferença significativa (P<0,05) entre os níveis de inclusão inulina para as variáveis fósforo e proteínas totais, e aos 35 novamente foi observada diferença significativa (P<0,05) para o fósforo. As demais variáveis não foram afetadas com a utilização da inulina. A utilização de 2,5g/kg de inulina proporciona melhor conversão alimentar para aves de 1 a 40 dias de idade. A inclusão de inulina reduz a deposição de gordura abdominal independentemente do tipo de ração. A utilização de ração com ingredientes de origem animal proporciona melhor rendimento de carcaça e maior rendimento de coxa. A utilização de inulina afetou os níveis de fósforo circulante aos 21 e 35 dias de idade. A utilização de inulina em rações de frango de corte eleva o custo da ração independente mente da utilização de ingredientes de origem animal ou vegetal

Lactic acid bacteria have been reported to be used as a health adjunct in food for u many years. However, these health benefits have not been proven. and how these bacteria pass through the digestion process and remain viable in the human intestinal tract is still not clear. The aim of this work was to isolate mutants from Lactobacillus acidophilus or Bifidobacterium bifidum that could tolerate the conditions of the digestion process (low pH and bile conduction) and to characterize these isolated mutants. Acid- and bile-tolerant mutants of L. acidophilus were isolated from parental strains successfully using natural selection techniques. These mutants survived and grew at conditions of pH 3.5 with 0.2% mixed bile salts added. After the selection, phenotypic characterization was identified to further clarify desirable traits for use as probiotic adjuncts in foods. These phenotypic characteristics included protease, aminopeptidase, ß-galactosidase, and bile salt hydrolase activity. Based on different protease, aminopeptidase, and ß-galactosidase activity, selected acid- and bile-tolerant mutants contained different growth characteristics compared with their parents. All the isolates tested showed different bile salt hydrolase activity, and this activity was not strain and medium dependent. Plasmid profiles and fatty acid analysis were conducted to provide more information of these acid/bile tolerant isolates and whether or not they were mutants from their parent strains rather than only adapted variants. Results showed the acid-/bile-tolerant isolates contained different plasmid profiles and cell wall fatty acids compared with their parents, which indicated these isolates were mutants. Protein expression by two-dimensional gel electrophoresis showed different protein expression patterns between acid- and bile-tolerant mutants and their parents. fm1her suggesting these isolates were mutants. We observed the protein production in parent strains decreased as the pH decreased. and protein expression in mutants remained the same as pH decreased. Two of the proposed health benefits of probiotic bacteria are anticholesterol activity and antimicrobial activity. These were evaluated using selected acid- and bile-tolerant mutants. Results showed no decrease of cholesterol in the test medium during bacterial growth. The observed antimicrobial activity was due to the presence of active cells. and this may relate to the acid production during cell growth and not to the production of antimicrobial substances. We concluded that the acid-/bile-tolerant isolates were mutants, and they survived and grew better in harsh environments compared with their parent strains. These mutants may be useful as a food adjunct in the future, but further study is needed to establish their use and possible probiotic benefits.

L'objectif de ce travail était de sélectionner de manière rationnelle une bactérie probiotique par la mise en place d'un crible ainsi que d'étudier et de comprendre l'impact du potentiel d'oxydoréduction (Eh) et du bullage de gaz sur la survie de Bifidobacterium bifidum dans un produit laitier fermenté. Nous avons tout d’abord développé des techniques de sélection des bactéries sur des critères de viabilité / vitalité (analyse par cytométrie en flux) ainsi que sur des critères de fonctionnalité (pouvoir antioxydant). Nous avons pu sélectionner des souches d'intérêt industriel ainsi qu'une souche d'étude académique, Bifidobacterium bifidum.Nous avons ensuite étudié l'effet de la modification du Eh par bullage de gaz sur la survie de B. bifidum dans un produit laitier fermenté. Les laits fermentés conditionnés sous atmosphère anaérobie (Azote) et/ou réductrice (Azote-Hydrogène) permettent une meilleure survie de la souche au cours du stockage (28 jours – 4 °C) par rapport au Contrôle. Puis, nous avons analysé l'effet d'une croissance sous différents Eh sur la viabilité en milieu modèle et la fonctionnalité de B. bifidum. Une croissance en condition anaérobie et/ou réductrice permet d’améliorer à la fois la résistance aux stress (stress oxydant d’ordre physiologique, stress aux sels biliaires et stress côlon), le pouvoir réducteur (sels de tétrazolium), le pouvoir antioxydant (test KRL et test des comètes) et l’adhérence par rapport au Contrôle. Une modulation des propriétés biochimiques membranaires sous Azote et sous Azote-Hydrogène pourraient expliquer ces phénomènes. L’augmentation des composés thiols exofaciaux et l’augmentation des acides gras insaturés à longues chaines est observée pour des cellules produites sous conditions Azote et Azote-Hydrogène. Ainsi ces conditions de croissance présentent une amélioration majeure de l’effet probiotique de B. bifidum, à la fois d’un point de vue de sa résistance aux stress que d’un point de vue de sa fonctionnalité / The aim of this work was to select rationally a probiotic strain by setting up a screening method as well as study and understand the impact of the redox potential (Eh) and gas bubbling on the survival of Bifidobacterium bifidum in a fermented dairy product. In a first time, we have developed selection techniques of probiotic bacteria on the criteria of viability / vitality (flow cytometry analysis) and on the criteria of functionality (antioxidant). We were able to select strains of industrial interest as well as an academic strain, Bifidobacterium bifidum.Secondly, we have studied effect of modifying redox potential by gas bubbling on the survival of B. bifidum in a fermented dairy product. Thus, fermented milk manufactured under anaerobic condition (Nitrogen,) and/or under reducing one (Nitrogen-Hydrogen) allow a better survival of the probiotic strain during the storage (28 days) at 4 °C compared with the Control fermented milk. Yogurt starter strains are not impacted. Then, we have analysed the effect of a growth under various Eh on the viability in model medium and the functionality of B. bifidum. A growth under anaerobic and/or reducing condition thus improved resistance to stress (physiological oxidative stress, bile salts and intestinal stress) the reducing power (tetrazolium salts) and the antioxidant power (KRL test and comet assay) compared with the Control. The adhesion to Caco-2 cells under these conditions is also improvedModulation of biochemical membrane properties under Azote and Azote-Hydrogen conditions could explain these phenomena. An increase in the proportion of exofacial thiol groups and in the proportion of unsaturated fatty acids with long chain was observed for cells produced under Nitrogen and Nitrogen-Hydrogen. These growth conditions present a major improvement for the probiotic effect of B. bifidum, regarding its resistance to stress and its functionality

The presented diploma thesis is focused on the preparation and the monitoring of the biological stability of beer enriched with probiotics. Probiotic bacterial strains of Lactobacillus acidophilus, Bifidobacterium breve and Bifidobacterium bifidum were used in this study. The theoretical part is divided into two sections. In the first section, probiotics are generally characterized, and their role within a gut microbiota is described. Next, the microbiology of particular probiotic microorganisms including the genera of Lactobacillus and Bifidobacterium is described. Then, some factors influencing the viability and the growth of probiotics are stated. In this section, biological effects of probiotics on the human organism and their potential clinical applications are described. The second section of the theoretical part deals with the technology of brewing, the chemical composition of beer and particular beer styles. In the experimental part, the methods of probiotic bacterial cell concentration and viability determination were optimized. Several techniques for determination of these parameters were selected, particularly the cultivation method, flow cytometry and the spectrophotometric measurement of turbidity. Then, the growth curves of the probiotic strains were measured in MRS medium. Probiotic bacteria were cultivated in model beer samples, i.e. in MRS media with several different concentrations of ethanol. It is possible to say that ethanol did not have significant effect on probiotics growth. Next, experimental cultivations of individual probiotic bacteria and their mixtures in nine real beer samples were conducted. No increase of viable cells concentrations was detected in the samples. On the contrary, a decrease of the concentrations was observed, mainly in the samples with individual bacterial strains. However, certain values of viable cells concentrations were determined at the end of the cultivations in all cases. A pale, top-fermented beer was brewed and supplemented with probiotics, and the concentrations of viable probiotic cells were monitored during 37 days of fermentation. A decrease of concentrations by two orders of magnitude of CFU/ml was observed in almost all samples. Yet, viable cells of probiotic bacteria were detected in all samples of beer at the end of the fermentation. Maximal concentration of viable probiotic cells in the brewed beer was determined with the cultivation method at (3,80 ± 0,14)10^5 CFU/ml. Chosen samples were analyzed with HPLC-RI method that quantified the common beer concentrations of ethanol in all chosen samples, lactic acid was not detected. Sensory analysis was conducted as well. Based on the results of the experimental part and the bibliography, an optimal technology of the preparation of beer enriched with probiotics is discussed in this study.

Foram conduzidos três experimentos no confinamento experimental do Departamento de Zootecnia da ESALQ/USP com o objetivo de estudar os efeitos de diferentes aditivos em rações para bovinos terminados em confinamento. No experimento 1 foram utilizados 100 bovinos machos Nelore castrados (392 kg), distribuídos em 20 baias, por 60 dias. As rações continham 41% de sorgo moído, 40% de polpa cítrica peletizada e 15% de silagem de cana-de-açúcar. Os tratamentos foram: (1) controle, (2) monesina sódica Rumensin (MON1), (3) monensina sódica Rumenfort (MON2), levedura Saccharomyces cerevisiae Yea-Sacc 1026 (LEV1) e levedura Saccharomyces cerevisiae Biosaf SC47 (LEV2). A IMS foi reduzida pelo tratamento MON1 (P<0,05), quando comparada ao tratamento controle. O GPD dos animais não foi afetado pelos tratamentos (P>0,05). A EA dos animais não foi afetada pelos tratamentos (P>0,05). O tratamento MON2 apresentou um menor rendimento de carcaça (P<0,05) e o tratamento MON 1 apresentou uma maior AOL (P<0,05). No experimento 2 foram utilizados 96 tourinhos Nelore não castrados (396 kg), distribuídos em 16 baias por 95 dias. Os tratamentos foram: (1) Controle, (2) levedura Saccharomyces cerevisiae Biosaf SC47 (LEV), (3) combinação de levedura Saccharomyces cerevisiae e bactérias probióticas na dose de 1g /bovino/dia (PROB1) e (4) combinação de levedura Saccharomyces cerevisiae e bactérias probióticas na dose de 3g/bovino/dia (PROB2). As rações continham 59% de polpa cítrica peletizada, 35% de farelo de glúten de milho úmido e 5% de feno de tifton 65. A adição dos aditivos levedura (Saccharomyces cerevisae) e a combinação de leveduras e bactérias probióticas não afetou a IMS o GPD e a EA dos animais (P>0,05). A energia líquida de manutenção e de ganho das rações também não foi afetada pelos tratamentos (P>0,05), assim como os dados de carcaça. No experimento 3, que avaliou a digestibilidade das rações, foram utilizados 20 tourinhos Nelore, alocados em 20 baias individuais durante 15 dias, sendo 10 dias de adaptação ao marcador e 5 dias de coleta de fezes. A ração foi a mesma utilizada no experimento 2, e o marcador utilizado foi o óxido de cromo. Os tramentos utilizados foram: (1) Controle, (2) monensina sódica Rumenfort (MON), (3) levedura Saccharomyces cerevisiae Biosaf SC47 (LEV), (4) combinação de levedura Saccharomyces cerevisiae e bactérias probióticas na dose de 1g /bovino/dia (PROB1) e (5) combinação de levedura Saccharomyces cerevisiae e bactérias probióticas na dose de 3g/bovino/dia (PROB2). Os aditivos testados não afetaram as digestibilidades da MS, da MO, da FDN e da PB das rações (P>0,05). Com os resultados obtidos é possível afirmar que bovinos Nelore, castrados ou não, confinados com rações com altos teores de concentrado ricos em co-produtos como polpa cítrica e farelo de glúten de milho úmido não apresentam melhor desempenho nem melhor digestibilidade dos nutrientes quando suplementados com monensina sódica ou com micorganismos probióticos. / Three trials were conducted at the ESALQ/USP Animal Sciences Department experimental feedlot to evaluate the effects of different feed additives in feedlot finished cattle. On trial 1 100 Nellore steers (392kg) were allocated to 20 pens for 60 days. Experimental rations had 41% ground milo, 40% dried citrus pulp and 15% sugarcane silage. Treatments were: (1) control, (2) sodium monensin Rumensin (MON1), (3) sodium monensin Rumenfort (MON2), (4) yeast culture Saccharomyces cerevisiae Yea-Sacc 1026 (LEV1) and (5) yeast culture Saccharomyces cerevisiae Biosaf SC47 (LEV2). DMI was reduced by MON1 trestment (P<0,05) in relation to control. WDG was not affected by treatments (P>0,05). Treatments did not affect FE (P>0,05). Animals on treatment MON2 showed the lowest dressing percentage (DP) and those on MON1 showed the highest rib eye area (REA) (P<0,05). Trial 2 used 96 young Nellore bulls (396kg), allocated to 16 pens for 95 days. Treatments were: (1) control, (2) Saccharomyces cerevisiae Biosaf SC47 (LEV), (3) Saccharomyces cerevisiae and probiotic bacteria mix at 1g /animal/day dose (PROB1) and (4) Saccharomyces cerevisiae probiotic bacteria mix at 3g/animal/day dose (PROB2). Rations contained 59% dried citrus pulp, 35% wet corn gluten feed and 5% Tifton 65 hay. Treatments didnt affect DMI, WDG and FE (P>0,05). Rations net energy for maintenance and gain were also not affect by treatments (P>0,05), well as carcass data. Trial 3 utilized 20 young Nellore bulls allocated to individual pens for 15 days (10 days for adaptation to marker and 5 days for data collection) to evaluate rations digestibility. Experimental ration was the same utilized on trial 2, with chromium oxide as an external marker. Treatments were (1) control, (2) sodium monensin Rumenfort (MON1), (3) yeast culture Saccharomyces cerevisiae Biosaf SC47 (LEV), (4) Saccharomyces cerevisiae and probiotic bacteria mix at 1g /animal/day dose (PROB1) and (5) Saccharomyces cerevisiae probiotic bacteria mix at 3g/animal/day dose (PROB2). Treatments did not affect rations DM, OM, NDF and CP digestibilities (P>0,05). Results show that Nellore cattle, castrated or not, feedlot finished receiving rations with high levels of byproducts such as dried citrus pulp and wet corn gluten feed dont have higher performance nor better nutrients digestibility when supplemented with sodium monensin or probiotic microorganisms.