Foram objetivos do presente experimento estudar os efeitos da administração da enramicina, em comparação com a monensina sódica, sobre a fermentação ruminal e a digestibilidade total em bovinos. Doze fêmeas bovinas não-gestantes e não-lactantes (675 kg ± 63 de PV) foram distribuídas inteiramente ao acaso aos três tratamentos formados por um grupo controle (ausência de antibiótico), um grupo tratado com enramicina (antibiótico não-ionóforo) e outro tratado com monensina (antibiótico ionóforo). A enramicina foi administrada na dose de 20 mg/animal/dia e a monensina na dose de 300 mg/animal/dia. O experimento teve duração total de 21 dias, sendo os 10 últimos destinados à aplicação do marcador (15 g de óxido crômico/animal/dia) e os últimos 5 dias destinados à coleta de fezes e amostragem dos alimentos. O 21º dia foi utilizado para colheitas de líquido ruminal realizadas às 0, 2, 4, 6, 8, 10 e 12 horas após a 1a refeição para determinação dos AGVs, pH e nitrogênio amoniacal. A monensina aumentou a concentração total de AGVs no tempo 12 horas após a alimentação e diminuiu a relação acético:propiônico nos tempo 0 e 6 h, em relação à enramicina, mas não em relação ao controle. Nenhum dos antibióticos testados alterou a proporção molar dos ácidos acético, propiônico e butírico, bem como o pH ou a concentração ruminal de nitrogênio amoniacal. Também não alterou o comportamento de consumo, avaliado em atividades de alimentação, ruminação e ócio. Nenhum dos antibióticos testados alterou a digestibilidade da matéria seca, proteína bruta, extrato etéreo, extrativo não nitrogenado, fibra bruta, fibra em detergente ácido, fibra em detergente neutro, amido, energia bruta ou os nutrientes digestíveis totais / The objective of this trial was to study the effects of enramycin administration, compared to sodium monensin, on ruminal fermentation and on total digestibility of diet nutrients in bovine. Twelve non-pregnant and non-lactating cows (675 ± 63 kg of BW) were randomly assigned to three treatments: control group (non-antibiotic), enramycin-treated group (non-ionophore antibiotic) and monensin-treated group (ionophore antibiotic). Treatments were 20 mg/animal/day of enramycin or 300 mg/animal/day of monensin. Trial lasted 21 days, the last 10 used for external marker administration (15 g of chromic oxide/animal/day) and the last 5 for feces collection and feed sampling. The 21st day was used for ruminal fluid sampling at 0, 2, 4, 6, 8, 10 and 12 hours after 1st meal to determine VFA, pH and ammoniacal nitrogen. Monensin increased total VFA concentration 12 h after feeding and decreased the acetic:propionic ratio at times 0 and 6 h, in relation to enramycin, but not when compared to control. The two antibiotics tested did not influence the molar proportion of acetic, propionic or butiric acids, pH, ammoniacal-N concentration, or dry matter intake and intake behavior, evaluated during activities of feeding, rumination and idleness. The two antibiotics tested did not alter the digestibility of dry matter, crude protein, ether extract, nitrogen-free extract, crude fiber, acid detergent fiber, neutral detergent fiber, starch, gross energy and total digestible nutrients (TDN), or the intake of digestible dry matter or TDN

Producing renewable energy from biomass or from the wastewater treatment process has gained momentum in the past 20 years. Anaerobic digestion has historically been used as one step in the waste treatment process, to both reduce the mass of waste that needs to be disposed of and to generate biogas. This process is typically only able to reduce 30-40% of the waste mass because of the recalcitrant nature of the waste streams being treated. Anaerobic pretreatment with the thermophilic bacteria Caldicellulosiruptor bescii (C. bescii) has been proven to increase the percentage of mass digested and consequently increase methane production to 75%-85%. However, even with the use of pretreatment with C. bescii, it still leaves 15%-25% of the methane potential wasted. In anaerobic digestion, volatile fatty acids (VFAs) are of interest because they are the precursors to the production of methane. By using HPLC-UV-vis techniques, VFAs can be speciated and quantified in as little as 12-minutes. Depending on the pretreatment system, operational procedures for both the pretreatment and anaerobic digestion system, and substrate, the type and composition of VFAs can vary. For example, in several experiments analyzed it was found that valeric acid is a VFA that is dominate in waste activate sludge treatments, while acetic acid is in higher proportions with manure substrates. Besides methane production, VFA monitoring can detect issues with a bioreactor performance. By tracking VFA trends, the health of the system can be assessed.

The development of anaerobic digestion processes has gained recognition for its potential for producing volatile fatty acids alongside bio-alcohols. In addition, the fermentation process and the products produced from biological fermentation have the possibility to overcome the abundance of organic waste in our society, which is potentially immensely rich in untapped valuable potential products. The current project aims at producing medium chained volatile fatty acids and alcohols from short-chain volatile fatty acids using hydrogen as an electron donor. For efficient conversion, inhibition of methanogenic microorganisms was performed by thermally pre-treating the microorganisms at 90 °C for 15 min. The highest observed concentrations of volatile fatty acid were 6.42 ± 0.09 g/L and the concentration of ethanol was 0.33±0.03 g/L. These concentrations were obtained with the addition of 4 g/L of liquid substrate and gas co-substrate (H2:CO2). Moreover, the predominant product from the present experiment was valeric acid and it reached its highest concentration of 1.41 g/L after 37 days. Interestingly, the addition of H2:CO2 co-substrate showed that this fermentation can be used for carbon capture and utilisation alongside hydrogen consumption in a ratio of 1:1 to increase the value of short-chain fatty acids. Furthermore, this can contribute to decreased CO2 emissions and reduced use of fossil resources for alcohol production which is in line with the global environmental goals.

Immediately post-hatch, broiler chicks are exposed to microbes that begin colonizing the gut, including environmental pathogens. One of the costliest enteric diseases in broiler production is necrotic enteritis (NE), caused by the ubiquitous opportunistic bacteria Clostridium perfringens (CP). With the worldwide reduction in antibiotic growth-promoters (AGPs), there is increased interest in natural alternatives to reduce disease and improve broiler health. The overall objective of the studies described herein was to apply probiotics or synbiotics to birds by in ovo application or orally before they leave the hatchery, then evaluate bird performance and various intestinal responses. Data were analyzed in JMP with LS Means to separate means with significance assigned at P ≤ 0.05 and trends at 0.05 < P ≤ 0.10. The first 21-day (D) study used 480 male Cobb 500 broilers randomly divided into one of four treatments using a 2x2 factorial design: a no-additive control (CTRL), a one-time oral application of synbiotic at the hatchery fed a basal diet (HS), an oral application of water at the hatchery with dietary synbiotics (DS), and a hatchery synbiotic plus dietary synbiotic (HSDS). Performance was measured on day-of-hatch (DOH), D3, D7, D14, and D21. mRNA abundance of various intestinal markers was measured at D7 and D21, including tight junction proteins ZO-1, ZO-2, and CLD-1; nutrient transporters SGLT1 and PepT1; and immune response markers TLR2, TLR4, and IL-10. HS lowered feed intake (FI) and feed conversion ratio (FCR) without lowering body weight (BW) from D14-21. There was greater abundance of PepT1 mRNA (P ≤ 0.1) and IL-10 mRNA (P ≤ 0.05) on D21 in HSDS. Second, a 21-day pilot study with 480 male and female Cobb 500 broilers was conducted to determine the optimum in ovo dosage level of a probiotic or synbiotic (PROB or SYNB) applied at embryonic day 18 (E18) with subsequent NE challenge using seven treatments: in ovo application of sterile water (CTRL), low (PROB-L or SYNB-L: 1x105 CFU), medium (PROB-M or SYNB-M: 1x106 CFU), or high (PROB-H or SYNB-H: 1x107 CFU) probiotic or synbiotic doses dissolved in sterile water. Performance measurements were taken on DOH, D4, D8, D14 and D21. On D8, NE lesion scores were not impacted by treatment. D8 ileal samples were taken for mRNA abundance of TLR4, IL-10, IL-1β, AvBD8, AvBD10, and AvBD13. SYNB-H had higher abundance of AvBD10 mRNA compared to CTRL (P ≤ 0.1), and higher IL-1β mRNA compared to SYNB-L (P ≤ 0.05). PROB-H and SYNB-H had better performance than the low and medium doses, but were not better than the CTRL. The high doses were chosen for subsequent studies. Third, a longer 42-day study using 1,630 Ross 708 male and female broilers was conducted consisting of the following six treatments. A negative control (NC): sterile water in ovo fed basal corn/soybean meal mash diet without NE challenge; antibiotic growth-promoter (AGP+): sterile water in ovo fed basal diet with virginiamycin (0.5 kg/MT) as an AGP with NE challenge; NC+: same as NC plus NE challenge; SI+: synbiotic in ovo fed the basal diet and NE challenged; SD+: sterile water in ovo fed basal diet supplemented with synbiotic (0.5 kg/MT feed) and NE challenged; and SID+: synbiotic in ovo fed basal diet with synbiotic (0.5 kg/MT feed) with NE challenge. Cumulatively, SID+ had lower FI and FCR than NC+, but no change in BW or BWG. The combination treatment (SID+) often had an additive effect compared to SD+ or SI+ alone on mRNA abundance and D7 cecal fatty acid profiles. SD+ and SID+ also had higher D42 lean:fat ratios compared to NC+. Last, a 42-day study was conducted using 1,630 male and female Ross 708 broilers and the in ovo application of probiotics and subsequent NE challenge with five treatments. NC: sterile water in ovo, fed basal corn/soybean meal mash diet without NE challenge; AGP+: sterile water in ovo, fed basal diet with virginiamycin (0.5 kg/MT of feed) as AGP with NE challenge; NC+: NC treatment, with NE challenge; PI+: probiotic in ovo, fed basal diet, with NE challenge; PD+: sterile water in ovo, fed basal diet supplemented with probiotic (1.3 kg/MT of feed), with NE challenge. The use of probiotics in this study had little effect on performance, lean:fat ratios, and cecal fatty acid profiles, but PD+ increased mRNA abundance of D14 TLR2, D14 TNF-α, and D42 LEAP2 in cecal tonsils compared to controls. PI+ increased mRNA abundance of D7 and D42 MUC2, D7 LEAP2, and D42 TNF-α in the ileum. PI+ increased mRNA abundance in the cecal tonsils of D7 TLR2 and D42 TNF-α. These studies yielded interesting results about probiotics and synbiotics during a NE challenge by evaluating performance, intestinal immune responses, and fatty acid profiles in the ceca of broilers. In conclusion, the probiotic in this study did not improve broiler health during a NE challenge, but synbiotic use in ovo and continuation in the feed showed improvement over in ovo or dietary application alone. Synbiotic improved FCR over a challenged control, and altered mRNA abundance in the small intestine. / Doctor of Philosophy / The poultry industry is one of the most popular animal protein sources worldwide. As with any livestock operation, industry goals include optimizing animal health and well-being, maximizing animal productivity, and producing quality products in the most cost effective manner. Improvements in genetics, nutrition, and management have increased productivity and cut costs. One important application was the low-level use of antibiotics in feed. These medications reduced the risk of disease outbreak in flocks, which led to healthier birds and improved growth rates. However, when global concern of antibiotic resistance in human medicine came to light, both the livestock industry and governing bodies implemented voluntary and mandatory reduction or elimination of antibiotics. Previously, these important antibiotics helped to control costly diseases. As they are removed, alternatives to antibiotics will be important in disease control and prevention. A major group of alternatives to antibiotics in poultry includes probiotics, prebiotics, and synbiotics. Probiotic bacteria are considered 'good bacteria' in the gut, and provide various health benefits to the host. Prebiotics are non-living substances that support the growth of healthy bacteria. A synbiotic is the combination of both probiotics and prebiotics in a single application method. The goal of this research project was to give probiotics or synbiotics to broiler chicks and evaluate their potential benefits and effects on bird performance and the immune response. Ideally, applying probiotic bacteria as early as possible might translate into early colonization of the gut with healthy bacteria. This included oral application of synbiotics at the hatchery, or by safely injecting them into part of the egg that is swallowed by the chick embryo before hatch. This egg application, or in ovo application, is a safe, effective, widely-practiced method of vaccinating chicks to jumpstart their defense against disease. By vaccinating them in ovo, they can start to prime the immune system before they even hatch. Applying probiotics in ovo may improve health after early gut colonization with beneficial microbes. Numerous studies on natural alternatives to antibiotics have been conducted, with varying results. Results of this research indicate that in ovo application of probiotics and synbiotics is safe. Birds that received probiotics in the feed often performed similar to those that received none. However, the in ovo use of synbiotics combined with the continued use in the feed after hatch improved efficiency in broilers during an intestinal disease challenge and improved various aspects of gut function. Overall, as antibiotics are phased out, using probiotics and synbiotics may improve poultry health, but continued research will help understand the optimum ways to use them.

This study evaluated degradable nutrient supply effects on VFA concentrations, fluid flux and pool sizes, rumen epithelial metabolic and absorptive genes, and post-absorptive muscle and blood responses. Six ruminally cannulated Holstein heifers (BW=330 ± 11.3 kg) were used in a partially replicated Latin Square experiment with four treatments consisting of beet pulp or timothy hay and barley or corn grain. Periods were18 d with 3 d diet adaptation and 15 d of treatment. During each period, d 10 to 14 was used for in situ nutrient degradation assessment, d 16 to 18 was used for rumen fluid sampling, and d 18 was used for rumen papillae and skeletal muscle biopsies and blood sampling. In situ ruminal starch disappearance rate (barley 7.61 to 10.5 %/h vs corn 7.30 to 8.72%/h; P = 0.05) and extent of fiber disappearance (timothy hay 22.2 to 33.4 % DM vs beet pulp 34.4 to 38.7 % DM P=0.0007) differed significantly among diets. Acetate (P = 0.02) and isovalerate (P = 0.008) molar percentages (% mol) were increased by timothy hay, but propionate (P = 0.06) and valerate (P = 0.10) molar percentages were decreased. Corn increased propionate (P = 0.02) and valerate (P = 0.049) molar percentage, but decreased butyrate (P = 0.04) molar proportion. Fluid volume and fluid passage rate, and individual VFA pool sizes were not influenced by diet (P > 0.05). Four epithelial genes, two metabolic and two absorptive, had increased expression on timothy hay diets (P < 0.15). Blood acetate concentration was influenced by treatment (P = 0.067) but no other blood metabolites were. Skeletal muscle metabolic rate was significantly increased on corn diets (P = 0.023). The results of this study provide a whole-system snapshot of how the rumen environment changes on diets differing in nutrient degradability and how the post-absorptive system adapts in response. / Master of Science / Over the last 50 years, dairy cattle have been bred to optimize milk production to meet growing population demands for milk and dairy products. The world population continues to grow and is projected to reach 9.7 billion people by 2050. Because of this growing population, there is an overwhelming need for dairy nutritionists to optimize the conversion of human inedible fibers into human edible food. The ruminant animal accomplishes this conversion through microbial fermentation of feedstuffs into volatile fatty acids (VFA), which account for approximately 70% of total energy available for meat, milk, and fiber production. Because rumen fermentation is a complex biochemical system, it is influenced by myriad factors including the substrate provided, the pH of the environment, and the absorptive and metabolic capacity of the rumen wall, among others. Although we understand how diet influences individual aspects of rumen fermentation, few studies have concurrently evaluated how diet influences the rumen chemical environment, the epithelium, and the resulting shifts in postabsorptive metabolism. Our study sought to understand the impacts of feedstuffs with different expected ruminally available starch and fiber supplies on these aspects of ruminant physiology. Six ruminally cannulated Holstein heifers were fed four different diets which used either beet pulp (low fiber ingredient) or timothy hay (high fiber ingredient), and ground corn (low starch ingredient) or ground barley (high starch ingredient). Heifers were fed each diet for a period of 18 days. From day 10 to day 14 of the period, nutrient degradability was assessed by incubating bags of feed in the rumen and conducting feed analysis after removed from the rumen. During the last four days of each period, rumen fluid samples, blood samples, muscle biopsies, and rumen papillae biopsies were collected. Feed analysis indicated that the starch sources differed in degradation rates (i.e. the speed of degradation) and fiber sources different in extent of rumen degradation (i.e. the percentage of feed degraded). Timothy hay caused greater concentrations of Total VFA, Total branched-chain VFA, acetate isobutyrate, and isovalerate. Timothy hay caused greater molar proportions of acetate and isovalerate. Corn caused greater molar proportions of propionate and valerate when barley caused greater molar proportions of butyrate. Rumen papillae biopsies were used to evaluate gene expression. Out of 14 genes, four were impacted by diet. Two rumen transporters responsible for the absorption of VFA had greater expression when animals were fed timothy hay diets versus beet pulp diets. Two metabolic genes also had greater expression due to timothy hay. The changes of both absorptive genes and metabolic genes is likely connected to the increased presence of VFA in the rumen. Lastly, blood acetate was increased, but there was not a specific ingredient or combination that caused the change. These results provide an overall snapshot of rumen fermentation characteristics and how changes in the rumen affect other biology.

La vinasse est le déchet liquide retiré de la base de colonnes de distillation de l'éthanol de canne à sucre à hauteur de 12 à 15 litres par litre d'alcool, ce qui entraîne une production estimée à environ 350 milliards de litres en 2012/2013 au Brésil. La vinasse a un pH faible et une forte demande chimique en oxygène, ce qui peut provoquer la désertification des terres, si elle est utilisée en excès comme amendement. En outre, une contamination des eaux souterraines liée aux épandages est observée dans certaines régions. L'aptitude de la vinasse à jouer le rôle de source d'éléments nutritifs pour la production de biohydrogène et d'acides gras volatils par des consortia microbiens anaérobies a été évaluée. Deux différents milieux à base de vinasse ont été proposés, un avec l’addition de jus de canne à sucre et l’autre avec l’addition de la mélasse comme source de carbone, et ont été comparés à un milieu supplémenté en saccharose. Des cultures bactériennes pures (4) et des consortia microbiens (7) ont été cultivées dans les milieux proposés et la production des acides gras volatils (AGV) et de biohydrogène ont été evalués. Le consortium LPBAH1, originaire d’un lac d’une ferme laitière et sélectionné pour la fermentation de la vinasse avec du jus de canne à sucre, conduit à un rendement en H2 de 7,14 molH2/molsucrose et à une teneur en hydrogène dans le biogaz d'env. 31% après optimisation. Par ailleurs, le processus optimisé en utilisant le consortium LPBAH2, originaire de fèces de chauves-souris frugivores, permet d'obtenir 3,66 molH2/molsucrose et 32,7% d'hydrogène dans le biogaz. Le processus proposé est d'une grande importance pour donner une destination plus rationnelle de la vinasse et d'élargir le bouquet énergétique brésilien en réduisant sa dépendance des combustibles fossiles. / Vinasse is the liquid waste removed from the base of sugarcane ethanol distillation columns at a ratio of 12-15 liters per liter of alcohol, resulting in an estimated production of approx. 350 billion liters in 2012/2013 in Brazil. Vinasse has a low pH and high chemical oxygen demand, which can cause land desertification when indiscriminately used as fertilizer. Also, underground water contamination is being observed in some regions. We evaluated the potential of vinasse as nutrient source for biohydrogen and volatile fatty acids production by means of anaerobic consortia. Two different vinasse-based media were proposed, using sugarcane juice or molasses as carbon source, and were compared to fermentation in a sucrosesupplemented medium. Pure cultures (4) and consortia (7) were cultured in the propose media and evaluated for volatile fatty acids (VFAs) and biohydrogen production. The consortium LPBAH1, originated from faeces of fruit bat, was selected for fermentation of vinasse supplemented with sugarcane juice and resulted in a higher H2 yield of 7.14 molH2/molsucrose and hydrogen content in biogas of approx. 31% after process optimization. Similarly, the optimized process using the consortium LPBAH2, originated from a lake of a dairy farm, resulted in 3.66 molH2/molsucrose and 32.7% hydrogen content in biogas. The proposed process is of great importance for giving a more rational destination to vinasse and expanding Brazilian energy matrix, reducing the dependence of fossil fuels.

Dans le cadre des recherches de l'ANDRA sur le confinement en couche géologique profonde de déchets radioactifs, une étude microbiologique a été menée sur l'eau interstitielle et l'argile du Callovo-Oxfordien (–490m, 165 millions d'années). Deux types d'études ont été menés, culturale et moléculaire.Malgré différentes tentatives d'extractions, et comme pour les études antérieures effectuées, aucun ADN n'a pu être extrait au cours de ce travail. Par contre, une approche culturale a permis de mettre en évidence la présence d'une microflore peu dense mais viable et métaboliquement assez variée : neuf espèces aérobies dont quatre facultatives et deux anaérobies strictes, de différents types métaboliques : sulfato-réducteur, réducteur de Fe(III), fermentaire et oxydation complète des substrats en CO2. Au vu des disponibilités in-situ en sources de carbone (SC) et d'énergie nécessaires à la croissance bactérienne, la production d'acétate et autres acides gras volatils ainsi que la production d'hydrogène pourraient potentiellement être actifs dans le Cox. L'étude des produits du métabolisme a permis d'identifier plusieurs agents biotiques (dont H2S) ayant potentiellement une activité biocorrosive. Par ce travail il apparait fondamental que la composante biologique soit prise en compte dans la conception du stockage, afin notamment d'éviter ou de limiter tout apport de matière organique exogène à la formation argileuse. Cette prise en compte biologique apparait cruciale pour tenter de restreindre le réseau trophique bactérien à ces conditions initiales, celles qui sont potentiellement présentes sur le site de stockage, qui concernent les seules SC et d'énergie autochtones. / In the framework of research of ANDRA about reversible deep geological radioactive waste, a microbiological study was conducted on pore water and Callovo-Oxfordian clay layer (-490m and 165 million years). Two types of studies were conducted, a cultural approach and a molecular approach.Despite various attempts of extraction, and as for the previous, no DNA could be extracted in this work. However, the cultural approach has highlighted the presence of a sparse microflora but viable and metabolically quite varied: nine aerobes species including four facultative anaerobes and two strictly anaerobes. They represent different metabolic types: sulfate-reducing, iron-reducing, fermentative and complete oxidation of substrates into CO2. In view of the availability of in-situ sources of carbon and energy required for bacterial growth, the production of acetate and other volatile fatty acids as well as hydrogen production could potentially be active in the clay layer of Cox and open to varied bacterial growth.The study of metabolic products has also identified several biotic agents (including hydrogen sulfide) having a potentially biocorrosive activity. Through this work it appears that the biological component is to be taken into account in the design of radioactive waste storage, in particular to avoid or minimize any contribution of exogenous organic matter in the clay formation.This biological consideration appears crucial to attempt to restrict bacterial trophic network on these initial conditions, that is to say those that are potentially present on the storage site, that concern solely autochthonous carbon and energy sources.

The pursuit towards an alternative solution to fossil fuel has facilitated science investigation initiatives that compare various options leading to biodiesel production. Besides conventional feedstock derived from vegetable oils, alternative sources that could be produced in large scale at competitive costs are the main scope of research in this field. This dissertation investigates the financial feasibility using organic solid waste as a feedstock, which results in the production of biodiesel through the conversion of volatile fatty acids (VFA) into lipids. As a result, based on existing references of: (i) capital and operating costs; (ii) internal rate of return; (iii) production and extraction yields for volatile fatty acids and lipids, we concluded that biodiesel production is competitive compared to subsidized biodiesel traded in regions of Europe and the United States. The sensitivity analysis took into consideration independent variables associated with: (i) investments in the plant; (ii) selling price of the biodiesel; (iii) costs of feedstock; and (iv) production yield. The results of such analysis showed the feasibility of using organic solid waste as a feedstock in 86.4% of the total 10,000 simulations, at the required internal rate of return. These results encourage research aims to examine this technology at a larger scale. The adoption of public policies for the urban wastes disposal and collection is also important for the implementation of such technologies. / A busca por soluções alternativas aos combustíveis fósseis tem impulsionado as iniciativas de pesquisa científica que comparam várias opções para a produção de biodiesel. Além das tradicionais fontes de matéria-prima provenientes de óleos vegetais, fontes alternativas, que possam ser produzidas em grande escala a custo competitivo, figuram como o principal escopo nesse campo de pesquisa. Essa dissertação investiga a viabilidade financeira da utilização de resíduo sólido orgânico como matéria-prima para a produção de biodiesel, através da conversão de ácidos graxos voláteis em lipídios. Como resultado, baseando-se em dados sobre: (i) investimentos e custos de operação; (ii) taxa interna de retorno requerida; (iii) taxas de extração e produção de ácidos graxos voláteis e de lipídios, conclui-se que a produção de biodiesel é competitiva quando comparada ao biodiesel subsidiado, que é negociado em regiões dos Estados Unidos e da Europa. A análise de sensibilidade realizada levou em consideração variáveis independentes tais como: (i) investimentos na planta; (ii) preço de venda do biodiesel, (iii) custos da matéria-prima e (iv) produtividade. O resultado de tal análise mostrou a viabilidade da utilização de ácidos graxos voláteis para a produção de biodiesel em 86,4% das 10.000 simulações, assumindo a taxa interna de retorno requerida. Esses resultados encorajam pesquisas adicionais para teste da tecnologia em maior escala. A adoção de políticas públicas para o descarte e coleta adequados dos resíduos sólidos urbanos também é importante para o desenvolvimento dessa tecnologia.

O presente trabalho teve como objetivo avaliar os efeitos do uso de leucena (Leucaena leucocephala (Lam.) de wit), em dietas para bovinos com ou sem adição de levedura (Saccharomyces cerevisiae) sobre a digestão (degradabilidade e digestiilidade), fermentação (produção de ácido graxos voláteis, amônia e metano) e população de protozoários no rúmen. Foram utilizados quatro bovinos machos mestiços, com peso vivo médio de 797 kg, canulados no rúmen em experimento com delineamento Quadrado Latino 4x4 em arranjo fatorial 2x2 com dois níveis leucena (20% e 50%) com feno de Cynodon dactylon cultivar coast-cross na presença ou ausência da levedura. Os tratamentos foram denominados: 20S = 20% de feno de leucena + 80% de de coast-cross ; 50S = 50% de feno de leucena + 50% de de coast-cross; 20L = 20% de feno de leucena + 80% de de coast-cross + 10 g de levedura; 50L = 50% de feno de leucena + 50% de de coast-cross + 10g de levedura. Os parâmetros ruminais avaliados foram: produções de ácidos graxos voláteis (AGVs); concentração de amônia; pH; produção de gás metano; taxa de passagem do líquido; degradabilidade in situ da MS, FDN e PB dos fenos de leucena e coast-cross; digestibilidade in vitro da MS dos fenos de leucena e coast-cross; contagem diferencial dos gêneros de protozoários ciliados. Houve efeitos da interação entre níveis de leucena e levedura nas dietas sobre as concentrações médias dos AGVs totais (P<0,05). As concentrações de ácido acético não apresentaram diferenças entre tratamentos. Mas as concentrações de ácido propiônico mostraram efeitos significativos para níveis de leucena na dieta e da interação N x L (P<0,05), com os maiores valores médios obtidos para o ácido propiônico em nível mais alto de leucena com levedura (19,14 mM). O aumento do nível de leucena favoreceu uma maior produção de ácido propiônico e esse efeito foi potencializado pela adição de levedura. Não houve diferenças na produção de ácido butírico nos níveis de leucena e de levedura (P>0,05) mas foram observados efeitos significativos da interação, evidenciando maiores concentrações do ácido butiríco no tratamento 20L. Não foram observadas diferenças (P>0,05), nas concentrações de amônia no rúmen, variando de 18,71 a 21,28 mg/100 mL no líquido ruminal. Houve diferença (P<0,05) na emissão de gás metano pelos animais, recebendo os diferentes tratamentos, ocorreu uma redução na produção de metano na dieta com nível elevado de leucena contendo levedura. Os valores encontrados para a cinética ruminal não foram afetados pelos tratamentos (P>0,05). A população de protozoários ciliados no rúmen sofreu alterações conforme o tratamento aplicado, tanto na concentração como na composição final da fauna, indicando um efeito associativo que ocorreu com o aumento de leucena na dieta juntamente com a levedura ou mecanismo de ação semelhante de ambos, dependendo do nível de leucena na dieta. / The present work had as objective to evaluate the effect of the use of leucaena (Leucaena leucocephala (Lam.) of Wit) in diets for bovines with or without yeast addition (Saccharomyces cerevisiae) on the digestion (degradability and digestibility), fermentation (production of volatile fatty acids, ammonia and methane) and ciliate protozoa population in rumen. Four crossbred male cattle, with average body weight of 797 kg, with rumen cannula were utilized in a Latin Square assay design 4x4, in factorial arrangement (2 x 2) with two levels of leucaena (20% and 50% DM) with hay of Cynodon dactylon cv coast-cross with or without addition of yeast. The treatments had been called: 20S = 20% of leucena hay + 80% of hay of coast-cross; 50S = 50% of leucena hay + 50% of hay of coast-cross; 20L = 20% of leucena hay + 80% of hay of coast-cross + 10 g of yeast and 50L = 50% of leucena hay + 50% of hay of coast-cross + 10g yeast. The ruminal parameters evaluated were: volatile fatty acids production; ammonia concentration; pH; gas production of methane; fluid outflow; in situ degradability in situ of the DM, NDF and CP of leucena and coast-cross hays; DM in vitro digestibility of leucena and coast-cross hays and concentration and generic counting of the ciliate protozoa. It was observed effect of the interaction between leucena levels and yeast in the diets on average total concentrations of VFA. No differences were observed in the concentrations of acetic acid among the treatments. But the propionic acid concentrations had shown significant effect for levels of leucena in the diet and interaction, with higher values obtained in the high leucaena level with yeast addition (19.14 mM). The increase of the leucaena level favored a higher production of propionic acid and this effect was powed by the yeast addition. There were no differences in the butyric acid production among the treatments, but significant effect of the interaction had been observed, evidencing higher concentrations of butyric acid in the treatment 20L. No difference had been observed in the rumen ammonia concentrations, varying from 18.71 to 21,28 mg/100 mL of ruminal liquid. A reduction in the methane production was observed in the animals receiving higher level of leucena with yeast addition. The values found for the kinetic ruminal had not been affected by the treatments. There was observed alteration in the rumen protozoa population according to treatment, as much in the concentration as mainly in the final composition of the fauna, indicating to have an associative effect that occurs with the increase of leucena in the diet together with the yeast addition or occurs a mechanism of similar action of both depending on the level of leucena in the diet.

Objetivou-se avaliar a taxa de emissão de metano (CH4) pela técnica do gás traçador hexafluoreto de enxofre (SF6) e fermentação ruminal dos animais alimentados com feno de Brachiaria brizantha em diferentes estágios de crescimento. Os três tratamentos foram: I-Feno de Brachiaria brizantha com 15 dias de crescimento, II- Feno de Brachiaria brizantha com 45 dias de crescimento e III- Feno de Brachiaria brizantha com 90 dias de crescimento. Seis bovinos da raça nelore, machos, castrados, canulados no rúmen e com peso médio inicial de 402 ± 51,62 kg foram utilizados em delineamento em quadrado latino 3x3 duplicado. O experimento teve duração total de 60 dias. A adaptação às dietas durou 7 dias. No oitavo dia foram feitas coletas de fezes (5 dias) e mensuração do consumo voluntário para determinação da digestibilidade in vivo dos alimentos. No 13° dia iniciaram-se as coletas de metano (7 dias) através da técnica do gás traçador hexafluoreto de enxofre (SF6). No 20° dia foram tomadas amostras do líquido ruminal às 0, 2, 4, 6, 8 e 10 horas após a primeira alimentação para determinação do potencial hidrogeniônico (pH), N-amoniacal e ácidos graxos voláteis do líquido ruminal. A idade de corte não afetou substancialmente a concentração total ou a proporção molar dos AGV, bem como o pH, embora a concentração de N-NH3 ruminal tivesse diminuído com o avanço da idade de corte. Para os dados de digestão, apenas a digestibilidade da PB aumentou e os dados dos CNF diminuíram com o avanço da idade. A produção de metano por animal/dia não foi afetada pela idade de corte do capim. Os animais alimentados com o feno produzido com 45 dias de crescimento do capim apresentaram diminuição de consumo de MS, o que resultou em maior produção de metano por unidade de MS ingerida. / The objective was to evaluate methane (CH4) emission rate by sulfur hexafluoride (SF6) tracer technique in bovines of the Nelore breed fed with Brachiaria brizantha hay in different maturation stages. The three treatments wore: I- Hay of Brachiaria brizantha with 15 days of maturation, II- Hay of Brachiaria brizantha with 45 days of maturation and III- Hay of Brachiaria brizantha with 90 days of maturation. Six bovines of the Nelore breed, males, castrated, rumen-cannulated, and 402 ± 51,62 kg of initial average weight had been used in a duplicated 3X3 latin square design. Trial lasted 54 days. The adaptation to the diets lasted 7 days. In the eighth day excrement collections (5 days) and feed sampling were done. In 13th day the methane collections were initiated using the sulfur hexafluoride SF6) tracer technique. The 20th day was used for ruminal fluid sampling at 0, 2, 4, 6, 8, and 10 hours after 1st meal for determination of pH, amoniacal-N, and volatile fatty acids in ruminal fluid. The ammoniacal nitrogen (NH3-N) concentration in treatment I was higher than II, 7,21; 2,22 mg/dl, respectively. Methane emission (g/kg DM) in treatment II was higher than I and II 23,41, 17,38, 20,02, respectively.