An individual’s naïve level of response (LR) to ethanol is predictive of their lifetime likelihood to abuse alcohol. LR is heavily genetically influenced, suggesting that the genes responsible for LR may also be central to the development of abuse disorders. Our laboratory uses the model organism C. elegans to investigate the genetic influences on responses to acute ethanol exposure. We recently found that changes in TAG levels can alter LR. From this result we investigated the role of long-chain polyunsaturated fatty acids (LC-PUFAs) as well enzymes involved in lipid modifications of proteins. We found that LC-PUFAs are necessary for acute functional tolerance and that supplementation of eicosapentaenoic acid is able to rescue AFT. We also identified mutations in several palmitoyltransferases, a thioesterase, and elongases that alter AFT. These novel results highlight the importance of fatty acids in the response to ethanol and suggest exciting new potential therapeutic targets.

Inhibition of fatty acid amide hydrolase (FAAH) or monoacylglycerol lipase (MAGL), the chief degradative enzymes of N-arachidonoyl ethanolamine (anandamide; AEA) and 2-arachidonoylglycerol (2-AG), respectively, elicits no or partial substitution for Δ9-tetrahydrocannabinol (THC) in drug discrimination procedures. However, combined inhibition of both enzymes fully substitutes for THC, as well as produces a full constellation of cannabimimetic effects. Because no published report to date have investigated whether an inhibitor of endocannabinoid hydrolysis will serve as a discriminative stimulus, the purpose of this doctoral dissertation was to investigate whether C57BL/6J mice would learn to discriminate SA-57 (4-[2-(4-Chlorophenyl)ethyl]-1-piperidinecarboxylic acid 2-(methylamino)-2-oxoethyl ester), a dual inhibitor of FAAH and MAGL, from vehicle in the drug discrimination paradigm. Also, we sought to determine whether inhibiting both enzymes, or inhibiting one enzyme was necessary to generate the SA-57 discriminative stimulus. Initial experiments showed that SA-57 fully substituted for either CP 55,940 ((-)-cis-3-[2-Hydroxy-4-(1,1-dimethylheptyl)phenyl]-trans-4-(3-hydroxypropyl)cyclohexanol), a high efficacy CB1 receptor agonist in C57BL/6J, mice or AEA in FAAH (-/-) mice. The majority (i.e., 23 of 24) of subjects achieved criteria of discriminating SA-57 (10 mg/kg) from vehicle within 40 sessions, with full generalization occurring 1-2 h post injection. CP 55,940, the dual FAAH-MAGL inhibitor JZL195 (4-nitrophenyl 4-(3-phenoxybenzyl)piperazine-1-carboxylate), the MAGL inhibitors MJN110 (2,5-dioxopyrrolidin-1-yl 4-(bis(4-chlorophenyl)methyl)piperazine-1-carboxylate) and JZL184 (4-[Bis(1,3-benzodioxol-5-yl)hydroxymethyl]-1-piperidinecarboxylic acid 4-nitrophenyl ester) fully substituted for SA-57. Although, the FAAH inhibitors PF-3845 and URB597 did not substitute for SA-57, PF3845 produced a two-fold leftward shift in the MJN110 substitution dose-response curve. In addition, the CB1 receptor antagonist rimonabant blocked the generalization of SA-57 as well as substitution of CP 55,940, JZL195, MJN110, JZL184 for the SA-57 discriminative stimulus. These findings taken together indicate that the inhibition of endocannabinoid-regulating enzymes serve as breaks to prevent overstimulation of CB1 receptors, and MAGL inhibition is the major driving force for generating the SA-57 discriminative stimulus.

Blood ethanol is a widely accepted marker for recent ethanol intake (within the last 4-6 h). However, the rapid elimination of ethanol from the body nearly always makes it impossible to assess ethanol ingestion beyond the most recent 6-8h. But serum fatty acid ethyl ester (FAEE) is detectable in the blood both when ethanol is presented and long after ethanol has been removed from the circulation. For this FAEE should be better marker for prior ethanol intake.

Master of Science / Grain Science and Industry / Greg Aldrich / Processing pet food can be beneficial, but can also have adverse effects on shelf-life and nutrient survival. Most affected are supplemental vitamins and essential fatty acids (EFA). Pet food complicates this relative to human foods by combining all elements into the product before processing and requiring an extensive shelf-life (up to 2 years). The objective of this research was to determine the effects of processing, diet, and storage conditions on vitamin (vitamin A, vitamin D₃, vitamin E, folic acid and thiamine) and omega-3 fatty acid (with an emphasis on eicosapentaenoic acid; EPA 20:5n3, and docosahexaenoic acid; DHA; 22:6n3) retention. The research was conducted in two separate experiments. Each experimental diet was produced on a single-screw extruder and triple-pass dryer. Target nutrients were evaluated in premixes in tandem to extruded diets. The vitamin study was conducted as a 3 X 2 X 2 factorial arrangement of treatments with 3 levels of dietary crude protein (CP), 2 screw speeds in the extruder, and 2 levels of time X temperature combinations in the dryer. Vitamins were added at 10 times normal levels to aid in analysis. The EFA study was conducted as a 3 X 3 factorial arrangement of treatments with 3 levels of dietary protein and 3 different omega-3 sources: fish oil, fish meal, or purpose-grown algae rich in DHA. In the vitamin premix study, the quantity of vitamins declined by approximately 50% over 6 months storage in ambient conditions (AMB; 20C, 50%RH), and all except folic acid were lost to some degree in stressed shelf life testing (SSLT; 50C, 70% RH) over 6 weeks. In all cases, the concentration of vitamins in food exiting the extruder and dryer were lower than target levels. As CP increased, the retention was higher (P ≤ 0.05) for vitamins A, E, and folic acid off the extruder (e.g. 225,352 vs. 219,184 and 206,249 IU/kg of vitamin A for high vs. medium and low CP, respectively), and vitamin D₃, E, and folic acid off the dryer (e.g. 9,047 vs. 7,473 and 6,945 IU/kg of vitamin D₃ for high vs. medium and low CP, respectively). During storage of finished pet food in AMB, vitamins A and D₃ were lost (P < 0.05) to the greatest degree (49 and 22%, respectively). The total retention following both processing and AMB storage was 27, 68, 78% for vitamins A, D₃, and E, respectively, while folic acid and thiamine were relatively stable. In SSLT storage, all vitamins except vitamin E were depleted more than 60% (P < 0.05) by 24 weeks, whereas total retention following both processing and SSLT storage was 3, 59, 43, 33, and 7% for vitamins A, D₃, and E, folic acid, and thiamine, respectively. This would suggest that beyond processing losses, the vitamins are relatively stable in premixes and foods if stored in AMB conditions. In the study to evaluate fatty acid stability within a vitamin premix, EPA, DHA, and total omega-3 fatty acids were relatively stable during storage over 6 weeks with losses no greater than 12% in stressed shelf life testing (SSLT; 40C, 70% RH). While in ambient conditions (23C, 50% RH) over 3 months, there was a total loss of EPA, DHA and total fatty acids by 17, 9, and 11%, respectively. Exiting the extruder and dryer, EPA and DHA were not affected by CP level or Omega-3 source. As SSLT storage of finished pet food increased through 24 weeks, EPA, DHA, and total fatty acids declined slightly (P < 0.05; 125, 82 mg/kg for EPA and 77, 60 mg/kg for DHA, and 418, 476 mg/kg for total fatty acids at 0 vs. 24 wk. As time in ambient storage reached 24 months, EPA, DHA, and total fatty acids declined slightly (P < 0.05; 125 vs. 78 mg/kg for EPA and 77 vs. 50 mg/kg for DHA, and 387 vs. 373 for total fatty acids at 0 vs. 24 mo.) Algal-DHA appears to be a stable source of DHA when compared to fish oil and fishmeal. During processing retention of fat soluble vitamins was less than water soluble vitamins, and the omega-3 fatty acids were relatively unaffected. Whereas, vitamins appeared to be more sensitive to temperature during storage and the omega 3 fatty acids more affected by time.

It is well established that replacing dietary saturated fatty acids with unsaturated fatty acids reduces cardiovascular disease (CVD) risk. Although epidemiological and clinical evidence indicate health benefits of consuming various fatty acid classes including n-9, n-6, and short- and longer-chain n-3 fatty acids, current dietary recommendations fall short of providing the optimal amounts of these fatty acids in daily diets. In addition, significant knowledge gaps remain in our understanding of the effects of, and mechanisms underpinning the action of, the various fatty acid classes on risk factors for CVD. The objective of this research was to contribute to the evaluation of health benefits of using different dietary oils, and determine how these benefits may play a role in improving public health and decreasing CVD risk. Additionally, this research examined effects of diet-gene interactions, endogenous fatty acid ethanolamides (FAEs) on body fat mass distribution as well as changes in the composition of gut microbiota following consumption of dietary oil treatments. The Canola Oil Multicenter Intervention Trial (COMIT) was conducted as a 5-phase randomized, controlled, double-blind, cross-over clinical trial. Each 4-wk treatment period was separated by 4-wk washout intervals. A total of 130 volunteers with abdominal obesity consumed each of 5 identical weight-maintaining, fixed-composition diets with one of the following treatment oils (60 g/3000 kcal) in the form of beverages: 1) conventional canola oil (Canola; n-9 rich), 2) high–oleic acid canola oil with docosahexaenoic acid (CanolaDHA; n-9 and n-3 rich), 3) a blend of corn and safflower oil (25:75) (CornSaff; n-6 rich), 4) a blend of flax and safflower oils (60:40) (FlaxSaff; n-6 and short-chain n-3 rich), and 5) high–oleic acid canola oil (CanolaOleic; highest in n-9). At endpoints, plasma fatty acid levels reflected the differences in fatty acid composition of five dietary treatments. All diets lowered total cholesterol (TC) compared with baseline. TC was lowest after the FlaxSaff phase and highest after CanolaDHA. The CanolaDHA treatment improved HDL-C, triglycerides, and blood pressure thereby reducing Framingham risk scores compared with other oils varying in unsaturated fatty acid composition. Homozygotes minor allele carriers of rs174583 (TT) on FADS2 gene showed lower (P<0.01) plasma EPA and DPA levels across all diets, but no differences were observed in DHA concentrations after the CanolaDHA feeding. In addition, plasma FAE levels were positively associated with plasma fatty acid profiles. Minor allele A carriers of rs324420 of FAAH gene showed a higher (P<0.05) plasma FAE levels compared with major allele C carriers across all diets, and showed higher (P=0.0002) docosahexaenoylethanolamide levels in response to the CanolaDHA diet. Impacts of consuming 60 g of five dietary oil treatments on gut microbiota composition were relatively minor at the phylum level and mainly at the genus level, while BMI contributed to a significant shift at the phylum level. In conclusion, consumption of a novel DHA-enriched canola oil improved blood lipid profile and largely reduced CVD risk. Diet-gene interactions might help identify sub-populations who appear to benefit from increased consumption of DHA and oleic acid. The metabolic and physiological responses to dietary fatty acids may be influenced via circulating FAEs, while the altered microbiota profile by shifts in MUFA and/or PUFA may be associated with specific physiological effect. Personalized diets varying in unsaturated fatty acids composition based on specific lifestyles, environmental factors, psychosocial factors, and genetic make-ups will become the future “healthy eating” recommendations to prevent CVD risk. / May 2016

Developing microbial systems capable of converting low cost lipids into value added products depends on the ability to acquire substrates from the growth media. Saccharomyces cerevisiae can acquire free fatty acids from the growth media and a portion of these lipids can be converted into new lipid products. However, they cannot acquire complex lipids from the growth media unless a nonspecific lipase is included. To circumvent lipase addition, we are genetically engineering S. cerevisiae to secrete a lipase into the growth media. We selected the LIP2 gene from Yarrowia lipolytica, which encodes a nonspecific lipase. Several modifications were made to the LIP2 gene to improve processing. Results identified strains secreting the most lipase. From these results, high producing strains were inserted into an oil inducible vector. Halo assays confirmed lipase secretion, while measuring the fatty acid composition confirmed triacylglycerol breakdown, and yeast uptake of the free fatty acids released.

La capacité des microalgues à accumuler des quantités importantes de lipides de réserve font de ces organismes de bons candidats pour envisager une production durable de biocarburants (biodiesel). Cependant, des verrous d’ordre technologique et biologique persistent avant d’atteindre une production économiquement viable. Dans le but de mieux comprendre les mécanismes et biosynthèse et d’accumulation des lipides chez les microalgues et de proposer des voies d’amélioration biotechnologiques, nous avons développé deux approches expérimentales complémentaires en utilisant la microalgue Chlamydomonas reinhardtii comme modèle. La première a été de caractériser par des techniques de protéomique et de lipidomique la composition des gouttelettes lipidiques s’accumulant en réponse à une carence en azote. Les données de protéomique nous ont permis de montrer que les gouttelettes lipidiques étaient des structures cellulaires dynamiques impliquées non seulement dans le stockage, mais aussi dans la biosynthèse, la remobilisation et le « trafficking » des lipides. Les protéines identifiées au cours de cette étude nous fournissent des gènes cibles d’intérêt pour mieux comprendre les voies de biosynthèse des triacylglycérols et accroître l’accumulation d’huile. La seconde approche, de génétique formelle, a consisté à rechercher puis à caractériser des mutants isolés à partir d’une banque de mutants d’insertion de C. reinhardtii. Deux mutants d’intérêt, l’un affecté dans la composition en acides gras (crfad7) et l’autre capable d’accumuler des lipides en l’absence de stress (coa1, pour constitutive oil accumulator 1), ont été isolés. / The ability of microalgae to accumulate high amounts of reserve lipids makes these organisms good candidates for the production of sustainable biofuel (biodiesel). However, both technological and biological bottlenecks remain to be overcome before profitable production is reached. With the aim to better understand lipid metabolic pathways in microalgae and further propose new strategies for biotechnological improvement, we have developed two complementary experimental approaches in the model microalga Chlamydomonas reinhardtii. As a first approach, we performed a proteomic and lipidomic characterization of oil bodies isolated from nitrogen-deprived cells. Based on proteomic data, we have concluded that oil bodies are dynamic structures involved not only in the storage, but also in oil biosynthesis, degradation and lipid homeostasis. The proteins identified in this study should provide useful targets for genetic studies aiming at increasing our understanding of triacylglycerol synthesis and further improve intracellular oil accumulation. The second approach, based on the development of a forward genetic screen, aimed at searching and further characterizing mutants isolated from a C. reinhardtii insertion library. Two mutants of interest, one affected in the fatty acid composition (crfad7), the other (coa1, for constitutive oil accumulator 1) able to accumulate reserve lipids in the absence of stress, have been isolated. The crfad7 mutant, affected in the expression of the unique ω3 fatty acid desaturase present in the C. reinhardtii genome, has been complemented and subjected to extensive phenotypical characterization.

Student Number : 9404757K - PhD thesis - School of Physiology - Faculty of Science / Natural secretions of oestrogen and progesterone vary according to menstrual phase in eumenorrhoeic women and have an affect on physiological systems that could consequentially influence exercise performance. In a series of menstrual phase comparative investigations (considering mainly the early follicular (EF), late follicular (LF) and mid-luteal (ML) phase), I aimed to elucidate the physiological relation of oestrogen and progesterone to fat metabolism and ventilation during endurance exercise and exercise performance. I measured plasma free fatty acid (FFA) kinetics during prolonged exercise from an intravenous infusion of K+[1-13C]palmitate in eumenorrhoeic women and found the change in palmitate rate of appearance and disappearance between menstrual phases to be related to the oestrogen/progesterone (E/P) ratio. Overall the results from this study suggest that oestrogen promotes increases in FFA availability during exercise, while progesterone mitigates this response. Therefore, a high oestrogen concentration and E/P ratio in the ML phase is required in order to produce a favourable FFA metabolic response for endurance events. In order to estimate plasma FFA oxidation rate using carbon-FFA tracers, the acetate correction factor which accounts for carbon-label retention in secondary metabolic pools, must be applied. When I derived the acetate correction factor by measuring fractional recovery of carbon-13 in expired CO2 from a constant infusion of Na+[1- 13C]acetate during submaximal exercise we found the acetate correction factor to be significantly lower in the ML than EF phase (average change from EF phase -1.8± 0.5%, p<0.05). Failure to account for the lower correction factor in the ML phase will result in a 6% underestimation of plasma FFA oxidation rate. Furthermore, since human serum albumin (HSA) routinely used as a carrier for parenteral delivery of FFA tracers has various disadvantages, I tested the feasibility of using 2-hydroxypropyl-b- cyclodextrin (HP-b-CD) as a possible alternative carrier. A comparison of expired CO2 enrichment following HSA-FFA (7.4±2.0 %o) and HP-b-CD-FFA (8.6±2.1%o) infusion during exercise showed that the HP-b-CD does not compromise natural in vivo behaviour of the FFA tracer (p=0.4). Progesterone-induced hyperventilation is occasionally reported during exercise in the luteal phase. I found that the change in ventilatory parameters (minute ventilation and respiratory rate) during exercise from EF to ML phase is related to both the oestrogen and progesterone concentration in the ML phase. However, the associated increase in respiratory rate throughout prolonged exercise in the ML versus EF phase did not increase metabolic demand and therefore could not be expected to exacerbate fatigue. When exercise performance was evaluated by means of a cycling time trial, I found a trend for best performance in the LF phase versus the EF phase (8 of 11 subjects improved by 5.2±2.9%, p=0.027), while no differences occurred between other menstrual phases. Metabolic and performance benefits of oestrogen may be concealed in the ML phase by the coincident increase in progesterone in this phase and thus a significant effect is often only evident with a high E/P ratio in the ML phase. The transient LF phase, characterised by the pre-ovulatory surge in oestrogen, reveals the maximum benefits of oestrogen on metabolism and performance during submaximal exercise.

Introdução:O Programa Alimentar Brasileiro Cardioprotetor (DICA Br) é pautado nas atuais diretrizes para tratamento e prevenção dos fatores de risco para doenças cardiovasculares (DCV). Objetivo:Avaliar o efeito do DICA Br nos biomarcadores inflamatórios de pacientes em prevenção secundária para doença cardiovascular. Métodos:Foram incluídos 369 participantes, referentes à amostra paulistana do DICA Br, com idade superior ou igual a 45 anos e que já tenham tido algum evento cardiovascular nos últimos 10 anos. Estes pacientes foram randomizados em dois grupos e acompanhados seis meses: grupo intervenção, que recebeu o DICA Br e grupo Controle, que recebeu orientação nutricional qualitativa para redução do valor calórico total da dieta e da ingestão de lipídios e sódio. Nas consultas inicial e final (intervalo de 6 meses), foram realizados: antropometria (peso, estatura e circunferência da cintura), avaliação da ingestão alimentar (recordatório alimentar de 24h R24h), dosagem de biomarcadores inflamatórios plasmáticos (interleucina (IL)01, IL06, IL08, IL010, IL012, fator de necrose tumoral (TNF)0, adiponectina e proteína C reativa(PCR)), pressão arterial, glicemia, insulinemia, perfil lipídico e ácidos graxos séricos. Resultados: As características demográficas dos participantes, no momento inicial do estudo,são semelhantes, não havendo diferença significativa entre os grupos. Em seis meses de seguimento, os grupos não diferiram quanto ao impacto das intervenções na concentração plasmática dos biomarcadores inflamatórios. é m, quando a análise é ajustada para presença de resistência à insulina, sexo, peso, sub relato e energia (kcal), foi observado aumento significativo da PCR (p interação=0,030) no grupo controle. Avaliando o impacto das intervenções na concentração plasmática de ácidos graxos, o ácido graxo alfa linolênico aumentou 0,04 cento no grupo intervenção, enquanto, no grupo controle, diminuiu 0,04 cento (p interação=0,008). outro lado, segundo o R24h, o grupo intervenção reduziu significativamente a ingestão de ácidos graxos ômega 06 (p interação=0,007). Além do ômega 06, o colesterol da dieta também apresentou redução significativamente maior no grupo intervenção (012,84 mg, p interação=0,036). Conclusão: Após seis meses de seguimento, o DICA Br não apresentou impacto na concentração plasmática de biomarcadores inflamatórios em indivíduos em prevenção secundária para doença cardiovascular. / Introduction: The Brazilian Cardioprotective Food Program (DICA Br) is based on the current guidelines for the treatment and prevention of cardiovascular disease risk factors (CVD). Objective: To evaluate the effect of the Brazilian Cardioprotective Food Program on the inflammatory markers of patients in secondary prevention for cardiovascular disease. Methods: In this Randomized Clinical Trial, atotal of 369 participants were included, referring to the São Paulo sample from the DICA Br study, aged 45 years or older, who had already had a cardiovascular event in the last 10 years. These were randomized into two groups and followed up for six months: Dica Br group and control group, which received a qualitative nutritional orientation to reduce the total caloric value of the diet and the intake of lipids and sodium. In the initial and final visit (6 months), anthropometry (weight,height and waist circumference), food intake evaluation (240hour dietary recall (R24h)), plasma inflammatory biomarkers (IL06, IL08, IL010, IL012, tumor necrosis factor (TNF) 0, adiponectin and C0reactive protein (CRP)), blood pressure, blood glucose, insulinemia, lipid profile and plasma fatty acids were evaluated. Results: The demographic characteristics of the participants at baseline are similar, with no significant difference between groups. At six months follow0up, the groups did not differ on the impact of interventions on inflammatory biomarkers. However, when the analysis was adjusted for the presence of insulin resistance, sex, weight and energy (kcal), a significant increase in CRP (p = 0.030) in the control group were observed. Evaluating the impact of interventions on plasma fatty acid concentration, alpha0linolenic acid increased by 0.04 per cent in the intervention group, while in the control group it decreased by 0.04 per cent (p0interaction = 0.008). On the other hand, according to R24h, the intervention group reduced significantly the intake of omega06 (p0interaction = 0.007). In addition to polyunsaturated fatty acids, dietary cholesterol also showed a significantly greater reduction in the intervention group (012.84 mg, p0interaction = 0.036). Conclusion: After six months of follow0up, DICA Br had no impact on the plasma concentration of inflammatory biomarkers in individuals in secondary prevention for cardiovascular disease.

Este trabalho teve o objetivo de avaliar o uso de monensina, levedura e a interação destes aditivos no metabolismo digestivo e desempenho de animais Nelores. Foram realizados dois experimentos. Experimento 1. Foram utilizados quatro novilhos Nelores com cânulas no rúmen e no duodeno para avaliar a degradabilidade, digestibilidade, biohidrogenação, microrganismos ruminais e emissão de metano quando fornecidos monensina e/ou levedura na dieta contendo óleo de girassol em experimento quadrado latino e arranjo fatorial 2x2. Os tratamentos consistiram em com e sem levedura e com e sem monensina. A levedura utilizada foi a Sacharomyces cerevisiae cepa 1026. As variáveis estudadas foram degradabilidade in situ, digestibilidade in vivo avaliada pelo método de indicador interno FDNi, pH, nitrogênio amoniacal e ácidos graxos de cadeia curta do rúmen, protozoários ciliados, biohidrogenação ruminal, e estimativa do número das bactérias Anaerovibrio lipolyica, Butyrivibrio fibrisolvens e Megasphaera elsdenii, por PCR em tempo real. Experimento 2. Foi realizado ensaio para avaliar o desempenho e características de carcaça e carne de touros Nelores utilizando os aditivos supracitados. Foram utilizados cinquenta e dois touros Nelores com aproximadamente 233kg em delineamento em blocos ao acaso. O fornecimento de monensina reduziu o número de protozoários ciliados no rúmen, aumentou a eficiêcia alimentar e a porcentagem de C18:1 trans10-11 e de C18:2 t11c15 na carne. O uso de levedura aumentou a degradabilidade efetiva da MS, o NDT da dieta, os protozoários ciliados, o pH ruminal, a expressão relativa da bactéria B. fibrisolvens, a ingestão de MS dos animais confinados, os ácidos graxos insaturados no conteúdo duodenal e os ácidos graxos saturados na carne, e reduziu a eficiência alimentar, os ácidos graxos saturados no conteúdo duodenal e os ácidos graxos insaturados na carne. Houve interação para a digestibilidade da FDN, ingestão de matéria seca por quilo de peso metabólico, espessura de gordura subcutânea, e ácidos graxos insaturados na carne. O uso de monensina em dieta com óleo foi eficiente para melhora na conversão alimentar. A utilização de cultura de levedura mesmo em dieta com óleo favoreceu os microrganismos ruminais e a energia da dieta. / This work had the objective of evaluate the use of monensin, yeast and the interaction of these additives on Nellore digestive metabolism and performance. It were conducted two trials. Experiment 1. It were utilized four Nellore steers with rumen and duodenum cannulas to evaluate the diet degradability, digestibility, biohydrogenation, rumen microrganisms and methane emission when supplied monensin and/or yeast on the diet with sunflower oil in a latin square desing and a 2x2 fatorial arranjement.The treatments were with and without yeast and with and without monensin. The yeast utilized was the Sacharomyces cerevisiae 1026 strain. The variables studied were in situ degradability, in vivo digestibility evaluated by indicator method NDFi, pH, ammonia nitrogen and rumen short chain fatty acid, ciliate protozoa, biohydrogenation, and estimative of bactéria Anaerovibrio lipolyica, Butyrivibrio fibrisolvens e Megasphaera elsdenii, by real time PCR. Experiment 2. A trial was realized to evaluate the performance and carcass and meat characteristics of Nellore steers utilizing the additives above. It were utilized fifthty two Nellore bulls with 233kg live weight average in a random blocks design. The monensin supplied decreased the protozoa number, the relative efficiency of B. fibrosolvens, increased feed efficiency and the percentage of C18:1 trans10-11 and C18:2 t11c15 in the meat. The use of yeast increased the effective degradability of DM, the TDN, ciliate protozoa, rumen pH, DM intake, unsaturated fatty acid on the duodenal content, and the saturated fatty acid in the meat, and decreased the feed efficiency, saturated fatty acid on the duodenum content and the unsaturated fatty acid of the meat. There were interaction effect to NDF digestibility, dry matter intake per kg of metabolic weight, fat thickness, and unsaturated fatty acid in the meat. The use of monensin was efficient to get the feed efficiency better. The utilization of yeast culture, even in a oil diet, was favorable to rumen microorganisms and the diet energy.