In April 2010, approximately 4.9 million barrels of oil were accidentally released into the Gulf of Mexico during the Deepwater Horizon Macondo Mc252 Oil Spill. Some of the surface oil was carried by prevailing winds and currents and reached the coast of Louisiana impacting marsh and marine ecosystems. One and a half years after this incident, a set of oiled marsh samples (2 grab samples) coupled with nearby subtidal and intertidal cores (12 cores) were collected from Barataria Bay, Louisiana to determine the probable source of petroleum residues present and to characterize the chemical composition of the oil. Plus, pre-spill core which was collected from Barataria Bay in 2007 was analyzed to identify the background hydrocarbon composition of the area. Polycyclic aromatic hydrocarbons (PAH), total petroleum hydrocarbons (TPH), biomarker, and stable carbon isotope compositions of selected samples were detected using a GC-MS and an elemental analyzer Conflo system coupled to a DeltaPlusXP isotope ratio mass spectrometer. The comprehensive chemical data allowed us to classify the pre and post-spill samples into 4 Groups. According to this classification, Group 1 and Group 2 samples had the highest concentrations of petroleum-derived hydrocarbons. Group 3 and background samples, on the other hand, was dominated by biogenic signatures. Although a direct connection between the detected and spilled Macondo oils results are complicated due to confounding factors (e.g., already present hydrocarbons and weathering processes), our biomarker data indicates that both oils have similar signatures. This close genetic relationship was also identified by stable carbon isotope analysis. The impact of the Macondo Mc252 Oil Spill in Barataria Bay appears to be limited to areas closer to the source. The oil has undergone moderate weathering and has penetrated into, the at least, the top 9 cm sediments. Additionally, to examine the decadal-scale history of sedimentation in these marshes, a sediment core was analyzed for the radioisotope 137Cs. The observed sedimentation rate of 0.39 cm/yr shows that oil pollutant input into Barataria Bay has been ongoing for at least 50-60 years.

Chlorinated paraffins (CPs) are ubiquitous environmental contaminants. They fulfill all of the criteria (persistent, toxic, and subject to long-range transport) for persistent organic pollutants (POPs) according to the United Nations Economic Commission for Europe (UNECE). CPs are also under consideration for inclusion in the Stockholm Convention on POPs. Their presence has been shown in various environmental matrices in the industrialized parts of the world, as well as in remote regions such as the Arctic. The aim of this thesis was to increase the limited knowledge of the presence of CPs in the environment, their sources to the environment, and the resulting human exposure. An analytical procedure for the determination of CPs in environmental samples based on gas chromatography coupled to electron capture detection (GC-ECD) has been developed. GC-ECD is a relatively inexpensive instrument that is fast and easy to operate. These advantages open up the possibility for a comprehensive screening of the occurrence of CPs in the environment, including developing countries. Furthermore, the occurrence of CPs in ambient air and in indoor air and dust was studied. Elevated CP concentrations in indoor air (<5-210 ng/m3) were observed compared to ambient air (0.7-33 ng/m3), which is indicative of the presence of indoor emission sources. Indoor air and dust concentrations were used to estimate the human exposure to CPs via the indoor environment. Comparison of the estimates to available dietary intake estimates indicated that the indoor exposure pathways are not negligible. CP concentrations in ambient air from urban Stockholm were higher than in rural Aspvreten, Sweden. This indicates the presence of additional (emission) sources in urban areas compared to rural sites. Additionally, a seasonal variation of air concentrations was observed at both locations, suggesting temperature dependent emission sources for CPs. These observations were supported by a substance flow analysis of CPs performed for Stockholm. This study estimated the major emission sources of CPs to the Stockholm environment to be emissions from painted surfaces and in-place sealants. / At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 2: Manuscript. Paper 3: Manuscript. Paper 4: Manuscript.

Orientadora: Telma Teresinha Berchielli / Banca: Dante Pazzanese Duarte Lanna / Banca: Lúcia Maria Zeoula / Banca: Ricardo Andrade Reis / Banca: Alexandre Amstalden Moraes Sampaio / Resumo: O trabalho teve por objetivo estimar a ingestão de matéria seca (IMS) e a digestibilidade da matéria seca (DMS) em bovinos alimentados com Brachiaria brizantha cv. Marandu. Para isso, foram realizados 3 experimentos. O primeiro experimento foi conduzido com o objetivo de validar a metodologia dos n-alcanos para estimar a produção fecal, ingestão e digestibilidade em novilhos Nelore alimentados com capim Marandu em duas diferentes idades de rebrota. No segundo experimento, avaliaram-se os efeitos da redução da freqüência de suplementação no desempenho, IMS, DMS e tempo de pastejo de novilhos mantidos em pastagem de capim Marandu de fevereiro a maio de 2006 e onde foi oferecido um suplemento a base de glúten de milho na quantidade de 0,5% do peso corporal/dia. O terceiro experimento foi realizado para verificar as implicações da redução da freqüência de fornecimento da suplementação na fermentação ruminal de novilhos mantidos em pastagem com capim Marandu. Como principais resultados observou-se que o par de alcanos C32:C33 foi adequado para estimar a IMS e o alcano C35 para estimar a DMS. O mês do ano exerceu importante efeito na disponibilidade e composição bromatológica da forragem, na IMS, na DMS, na produção de ácidos graxos de cadeia curta ...(Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The objectives of this work were to estimate the dry matter intake (DMI) and the dry matter digestibility (DMD) in beef cattle feeding Brachiaria brizantha cv. Marandu. For that, 3 experiments were accomplished. In the first experiment, the objective was to analyser the n-alkanes methodology to estimate the faecal production, intake and digestibility in Nelore steers feeding with Marandu grass in two different regrowth ages. In the second experiment, was evaluated the effect of the reduction of the supplementation frequency in the performance, DMI, DMD and grazing time of steers maintained in grazing of Marandu grass of February to May of 2006 and receiving a supplement the base of corn gluten in the amount of 0.5% of the body weight/day. The third experiment was accomplished to verify the implications of the decreasing the frequency of supplementation in the ruminal fermentation of steers maintained in Marandu pasture. Observed that the pair of alkanes C32:C33 was suitable to estimate DMI and the alkane C35 to estimate DMD. The month of the year cause important effect in the forage availability and the bromathologic composition, in the DMI, DMD and short-chain fatty acids production and, consequently, in the performance of bovine in pasture. The supplementation frequency doesn't affect DMI, the digestibility and the performance of bovine... (Complete abstract, click electronic access below) / Doutor

O gênero Croton possui aproximadamente 1300 espécies amplamente distribuídas em zonas tropicais e subtropicais do novo e velho mundo e é o segundo maior gênero de Euphorbiaceae. No presente trabalho, foram analisadas a composição e a morfologia das ceras foliares cuticulares de 13 espécies de Croton. Para a maioria das espécies, foram amostrados três indivíduos. A morfologia das ceras foi analisada por microscopia eletrônica de varredura. Diversos tipos de depósitos cerosos foram observados (amorfos, plaquetas, grânulos), principalmente na face adaxial e caracterizando grupos de espécies. A observação dos padrões de depósitos cerosos de várias espécies foi prejudicada na face abaxial, devido à alta densidade de tricomas. As ceras foram extraídas por três imersões consecutivas das folhas em diclorometano e a separação das classes dos constituintes foi feita por cromatografia em camada delgada preparativa. A análise da distribuição dos constituintes foi realizada por cromatografia a gás acoplada a espectrometria de massas. n-Alcanos e álcoois primários foram detectados em todos os indivíduos analisados. Triterpenos também são muito comuns, não tendo sido detectados em apenas uma espécie. Os esteroides são constituintes raros nas espécies analisadas. Os resultados da distribuição de n-alcanos, álcoois primários e triterpenos foram utilizados para o estabelecimento de afinidades químicas por meio de análises de agrupamento pelo método UPGMA, empregando-se distâncias euclidianas (n-alcanos e álcoois) e coeficiente de DICE (triterpenos), baseando-se na distribuição de cada classe de constituinte isoladamente e combinando-se as distribuições de n-alcanos e álcoois primários. Não se notou congruência entre as topologias dos dendrogramas de afinidades químicas e a filogenia molecular do gênero. Observou-se coerência entre algumas afinidades químicas e características morfológicas, como tipos de tricomas foliares e presença de glândulas peciolares. A distribuição de n-alcanos, álcoois primários e triterpenos mostraram-se úteis como caracteres da maioria das espécies analisadas. Entre os constituintes analisados, distribuição de álcoois primários revelou-se o melhor marcador para a caracterização de espécies. A variação intraespecífica, no entanto, impede que esses caracteres sejam úteis como marcadores taxonômicos de algumas espécies de Croton / Croton comprises nearly 1300 species distributed in tropical and subtropical areas of either the New or Old Worlds, making up the largest genus of Euphorbiaceae. In the present work, the chemical composition and the morphology of the foliar cuticular waxes of 13 species of Croton were analized. Three individuals were sampled for analyses of most species. The morphology of the waxes was analyzed by scanning electron microscopy. Several types of wax deposits were observed (amorph, platlets, granules), chiefly on the adaxial side, characterizing groups of species. The observation of wax deposits on the abaxial side was hampered in several species due to the high density of trichomes. The cuticular wax was extracted by three successive immersions of the leaves in dichloromethane, and the separation of the constituent classes was achieved by preparative thin layer chromatography. The analyses of the distribution of the constituents were performed by gas chromatography coupled to mass spectrometry. n-Alkanes and primary alcohols were detected in all analyzed individuals. Triterpenes were also very common, having not been detected in only one species. Steroids are rare constituents in the analyzed species. The results of the distribution of n-alkanes, primary alcohols and triterpenes were used for the establishment of chemical affinities using cluster analysis by the UPGMA method and Euclidean distances (n-alkanes and alcohols) and DICE coefficient, based on the distribution of each constituent class alone and combining the distribution of n-alkanes and primary alcohols. No congruence was noted between the topologies of the dendrograms of chemical affinity and the molecular phylogeny of the genus. Coherence was observed between chemical affinities and morphologic characteristics, such as types of foliar trichomes and petiolar glands. The distribution of n-alkanes, primary alcohols and triterpenes were shown to be useful as characters for most analyzed species. Among the constituents analyzed, the distribution of primary alcohols was the best marker for species characterization. Intraspecific variation, however, precludes the use of these characters as taxonomic markers of some Croton species

Indiana University-Purdue University Indianapolis (IUPUI) / The Indian summer monsoon (ISM) is the dominant hydrometeorological phenomenon that provides the majority of precipitation to southern Asia and southeastern Tibet specifically. Reliable projections of ISM rainfall are critical for water management and hinge on our understanding of the drivers of the monsoon system and how these drivers will be impacted by climate change. Because instrumental climate records are limited in space and time, natural climate archives are required to understand how the ISM varied in the past in response to changes in climatic boundary climate conditions. Lake sediments are high-resolution natural paleoclimate archive that are widely distributed across the Tibetan Plateau, making them useful for investigating long-term precipitation trends and their response to climatic boundary conditions. To investigate changes in monsoon intensity during the Holocene, three lakes were sampled along an east-west transect in southeastern Tibet: Galang Co, Nir’Pa Co, and Cuobu. Paleoclimate records from each lake were developed using isotopic (leaf wax hydrogen isotopes; δ2H), sedimentological, and geochemical proxies of precipitation and lake levels. Sediments were sampled at high temporal frequencies, with most proxies resolved at decadal scales, to capture multi-decadal to millennial-scale variability in monsoon intensity and local hydroclimate conditions. The ISM was strongest in the early Holocene as evidenced by leaf-wax n-alkane δ2H at both Cuobu and Galang Co corresponding with Cuobu’s higher lake levels and effective moisture. Monsoon intensity declined at Cuobu and Galang Co around 6 ka which corresponds to reduced riverine sediment influxes at Cuobu and deeper lake levels at Galang Co. The antiphase relationship between lake levels and monsoon intensity at Galang Co is attributed to air temperatures and effective moisture, with a warmer and drier local hydroclimate driving early Holocene low lake levels. The late Holocene ISM was more variable with wet and dry periods, as seen in the Nir’Pa Co lake level and leaf wax n-alkane δ2H record. These records demonstrate coherent drivers of synoptic and local hydroclimate that account for Holocene ISM expression across the southeastern Tibetan Plateau, indicating possible drivers of future monsoon expression under climate change.

Earth's climate is prone to natural and episodic cycles. The most recent period of climate change, the only one to be caused by humans, is significantly affecting species composition and landscapes. Northern expansion of the Boreal Forest in Canada is one of the expected outcomes, and tree line migration northward is one of the anticipated changes. Previous studies have found that many human activities like agriculture, grazing, and pastoralism can significantly affect tree line movement. Improving our ability to examine past tree line dynamics can be achieved using archival records in lake sediments. In this study, we focused on three sediment biomarkers that may be related to the presence of trees in a lake's catchment: n-alkanes, lignin-derived phenols, and stable isotopes of carbon. We examined the composition of these markers in sediment from 19 lakes in Saskatchewan spanning 4 ecoregions, from Prairie Grassland to Boreal Plain, to determine the biomarker signature for lakes in each ecoregion and relating them to land cover (trees vs herbaceous plants) in the catchments of each lake. The results showed that n-alkane composition was significantly correlated to the proportion of trees to herbaceous plants in a lake's catchment, raising the possibility that these can be used to infer the presence of trees in sediment records. The C/N ratio and δ¹³C were not effective in distinguishing ecoregions or land cover composition, likely due to algal production in the lake and agricultural activities in the surrounding farmland, while lignin-derived phenols appeared to be affected by unknown factors.

Este trabalho tem como objetivo estudar as fontes de matéria orgânica em sedimentos ao longo do Sistema Estuarino-Lagunar de Cananéia-Iguape, por meio de diferentes indicadores geoquímicos. Foram coletados 12 testemunhos. Os 10 centímetros superficiais foram fatiados de 2 em 2 centímetros, totalizando 60 amostras. Análises granulométricas, de razão C/N, 13C/12C e a datação de alguns dos testemunhos, foram feitos pelo grupo de Oceanografia Geológica do IOUSP. Os marcadores orgânicos moleculares utilizados foram os hidrocarbonetos alifáticos, álcoois graxos e esteróides, analisados por GCFID. O total de hidrocarbonetos alifáticos variou entre 0,571 a 9,932 g g-1. Os álcoois totais variaram de 0,318 a 35,291 g g-1. Os esteróides totais variaram de 0,241 a 11,054 g g-1. Para interpretação dos dados foram utilizadas as razões entre n-alcanos ímpares e pares leves (C21) e pesados (C22), somatório de álcoois graxos leves e pesados, relação entre a soma de coprostanol e epicoprostanol sobre o total de esteróides e relação entre epicoprostanol e coprostanol. Os resultados das razões indicam uma origem terrestre dos compostos orgânicos analisados com uma clara predominância da contribuição da vegetação de manguezal da região. Entretanto, existe uma discreta introdução de hidrocarbonetos de petróleo e esgoto domésticos nãotratados em alguns pontos isolados do Sistema Estuarino-Lagunar de Cananéia-Iguape. / This work has the objective in evaluate the sources of organic matter in sediments of the Cananéia-Iguape Estuarine-Lagunar System, using several geochemical markers. For the study area, 12 sample points were chosen, where the corers were obtained. For each point, the superficial 10 centimeters, sliced in each 2 centimeters, totalizing 60 samples. Granulometric analysis, C/N and 13C/12C ratios and dating of some cores, were realized by the Geological Oceanography group of IOUSP. The molecular organic markers used were the aliphatic hydrocarbons, fatty alcohols and steroids, analyzed by GC-FID. The total hydrocarbons varied from 0.571 to 9.932 g g-1. The total fatty alcohols ranged from 0.318 to 35.291 g g-1. The total steroids varied from 0.241 to 11.054 g g-1. For interpretation of data, some relations were used such as odd/even hydrocarbons C21 and C22, total short and long chain fatty alcohols, the coprostanol + epicoprostanol divided by total sterols and epicoprostanol/coprostanol. The results of the ratios showed a terrestrial origin of the organic matter with a clear predominance of the contribution of the mangrove higher plants of the region. However, there is a discrete introduction of petroleum hydrocarbons and untreated domestic sewage in isolated points of the Estuarine-Lagunar System of Cananéia-Iguape.

This study is a multi-proxy analysis of a 30-m section of a Barremian-Aptian succession of interbedded, grayish black (N2) and black (N1) limestones from a quarry of the Sierra de Prada. Index taxa include planktic foraminifera Globigerinelloides blowi and Hedbergella sigali, which combined with δ13C data from Cresmina and Gorgo a Cerbara sections indicate a late Barremian to early Aptian age. The rocks are organic-rich with 0.67 - 3.10 wt% total organic carbon (TOC). A marlstone interval (~1m) at 2.24 m has a low bioturbation index (1), TOC ~6.66 wt%, framboidal pyrite, and enrichment spikes of major, biolimiting, and redox-sensitive trace elements (Al, Si, Ti, P, Fe, and Mo, Cr, Cu, V, Th), indicating an anoxic episode. Biomarker analyses show a predominance of n-alkanes (≤nC20) at this level, suggesting an in situ origin of organic matter from phytoplankton. Pr/Phy ratios below 2 imply that organic matter did not reach overmaturity.

O estudo foi realizado em área pertencente a Embrapa Pecuária Sul, Bagé, RS, com o objetivo de avaliar a emissão de metano, consumo a pasto, desempenho, e comportamento ingestivo de novilhos de corte em pastagem natural (CN), pastagem natural fertilizada com nitrogênio (CNA) e pastagem natural fertilizada com nitrogênio e sobressemeada com Lolium multiflorum e Trifolium pratense (CNM). O delineamento foi inteiramente casualizado com três repetições. Foram utilizados novilhos da raça Hereford em pastoreio contínuo com lotação variável para atingir oferta diária forragem de 12 kg MS 100 kg PV-1 (12% PV). Para o primeiro artigo, as avaliações foram feitas no verão, outono, inverno e primavera de 2013. As emissões de metano foram estimadas pela técnica do gás marcador hexafluoreto de enxofre. Para avaliação do consumo foi utilizada a técnica dos n-alcanos. Para o segundo artigo, avaliações com GPS foram feitas na primavera de 2013, outono e primavera de 2014. A localização e o deslocamento dos animais foram registrados, e avaliações visuais das atividades dos animais foram feitas a cada 10 minutos, do nascer ao pôr-do-sol, durante dois dias consecutivos em cada época. Os animais apresentaram bom desempenho ao longo do ano, com ganhos médios diários de 0,272, 0,467 e 0,514 kg para os tratamentos CN, CNA e CNM, respectivamente. As maiores emissões de metano foram durante a primavera. O CN apresentou maior quantidade de metano emitida por kg de ganho de peso (577,94, 337,69 e 387,18 g CH4 kg GPV-1 para o CN, CNA e CNM, respectivamente). Animais em CN passaram mais tempo em atividade de pastejo do que aqueles em CNA e CNM. Durante as épocas, menor atividade de pastejo foi na primavera de 2013 em comparação com outono de 2014 e primavera de 2014. Para as variáveis tempo em ruminação e em outras atividades não houve diferença nem para tratamentos nem para época de avaliação. Para o deslocamento, não houve diferença entre os tratamentos, entretanto houve efeito para as estações avaliadas, onde os animais caminharam menos no outono de 2014 comparado a primavera de 2013 e 2014. As estações do ano afetaram mais o consumo de MS e a emissão de metano que os níveis de intensificação. No entanto, considerando o desempenho dos animais, a inclusão de insumos permite menor emissão de metano por quilo de ganho de peso. / The study was conducted in an area of Embrapa Southern Region Animal Husbandry, Bagé, Rio Grande do Sul, Brazil, in order to assess the methane emission, forage intake, performance, and feeding behaviour of beef steers in natural grassland (NG), natural grassland fertilized with nitrogen (NGF) and natural grassland fertilized with nitrogen and oversown with exotic cool season species Lolium multiflorum and Trifolium pratense (NGFS). The design was completely randomized design with three replications. Hereford steers were used in continuous grazing with variable stocking rate to achieve daily supply of 12 kg DM 100 kg LW-1 (12% PV). For the first paper, evaluations were made in the summer, fall, winter and spring of 2013. Methane emissions were estimated by sulfur hexafluoride tracer gas technique. To evaluate the dry matter intake was used the n-alkanes technique. For the second paper, evaluations with GPS were made in spring 2013, fall and spring 2014. The location and the movement of animals have been recorded, and visual assessments of animal activities were made every 10 minutes, from sunrise to sunset, for two consecutive days in each season. Animals showed a good performance throughout the year, with average daily gain of 0.272, 0.467 and 0.514 kg for NG, NGF and NGFS treatments, respectively. The highest methane emissions were during spring. The NG presented a higher amount of methane emitted per kg of weight gain (577.94, 337.69 and 387.18 g CH4 kg BWG-1 to NG, NGF and NGFS, respectively). Animals in NG spent more time in grazing activity (71%) than those in NGF (63%) and NGFS (64%). During seasons, less grazing activity was in the spring of 2013 (62%) compared with fall 2014 (67%) and spring 2014 (68%). For the variables time ruminating and in other activities there was no difference either for treatments or for season. For displacement, there was no difference between treatments, however was effect on the seasons evaluated, where the animals walked less in the fall of 2014 compared to the spring of 2013 and 2014. The seasons affected more DM intake and methane emissions that intensification levels. However, considering the animals performance, the inclusion of inputs allows lower methane emissions per kilogram of weight gain.

Objetivou-se avaliar como diferentes estratégias de manejo do pasto de azevém anual interferem na produção animal, no consumo de forragem e na emissão de metano por ovinos em sistema de integração lavoura-pecuária (SILP) (Capítulo II). Já no Capítulo III objetivou-se avaliar as técnicas dos nalcanos e do nitrogênio fecal na estimativa do consumo de forragem por ovinos em pastos de azevém anual. Os experimentos foram conduzidos nos anos de 2011 e 2012 na Estação Experimental da UFRGS. Foram utilizados ovinos em um SILP de soja e milho no verão, em rotação com azevém anual no inverno. Para ambos os Capítulos (II e III) foram estudados dois métodos de pastoreio (contínuo e rotativo) e duas intensidades de pastejo (moderada e baixa; 2,5 e 5 vezes o potencial de consumo de matéria seca, respectivamente) em um delineamento de blocos casualizados com 3 repetições. Para o Capítulo II, no primeiro experimento os animais experimentais eram cordeiros, enquanto no segundo foram ovelhas em lactação. Os resultados indicaram que o ganho médio diário (GMD) dos cordeiros foi maior (P<0,05) no método de pastoreio continuo que no método de pastoreio rotativo, independente da intensidade de pastejo. O ganho de peso vivo por área (GPV) apresentou a mesma resposta em ambos os experimentos, com maior GPV na intensidade de pastejo moderada (P<0,05). No experimento 1, o consumo de matéria seca (CMS) foi maior para o método de pastoreio continuo, enquanto no experimento 2 não houve diferenças entre métodos e intensidades. As emissões de CH4 diárias por animal não diferiram entre tratamentos em ambos os experimentos (P>0,05), porém, quando expressas em g CH4 kg GPV-1 as emissões foram em média 15,33% maiores (P<0.05) para o método de pastoreio rotativo, independente da intensidade de pastejo. Os resultados afirmam que as emissões de metano por animal não são afetadas pelos tratamentos impostos. Porém, do ponto de vista de sistema o método de pastoreio contínuo o mais eficiente, por apresentar menor emissão de metano por kg de ganho de peso vivo, independente da intensidade de pastejo. Para o Capítulo III, foram utilizados apenas cordeiros. Utilizou-se a metodologia dos n-alcanos e do nitrogênio fecal, por meio de coleta total de fezes com o auxílio de bolsas coletoras. Na avaliação entre os n-alcanos, verificou-se melhores resultados quando utilizando o par C31:C32. Para a metodologia do nitrogênio fecal, as equações propostas por Wang et al. (2009) e por Azevedo (2011) foram as melhores (P<0,05). A técnica do nitrogênio fecal mostrou-se mais acurado do que o uso dos n-alcanos, que superestimou os valores de consumo. / The aim of this study was to evaluate how different management strategies of Italian ryegrass affects animal production, forage intake and methane emissions by sheep in integrated crop-livestock system (ICLS) (Chapter II). In Chapter III, we aimed to evaluate the techniques of n-alkanes and fecal nitrogen in estimating forage intake by sheep grazing on ryegrass. The experiments were conducted in 2011 and 2012 at the UFRGS Experimental Station. The ICLS soybeans and corn crops in summer, in rotation with grazed Italian ryegrass in winter. For both chapters (II and III) two stocking methods (continuous or rotational) and two grazing intensities (moderate and low, 2.5 and 5 times the potential dry matter intake, respectively) were studied in a randomized block design with three replications. In Chapter II, in the first experiment, the experimental animals were lambs, while in the second were lactating ewes. The results indicated that the average daily gain (ADG) of lambs was higher (P<0.05) in the continuous method than in rotational grazing method, regardless of grazing intensity. The live weight gain per area (LWG) showed the same response in both experiments, with higher LWG values in moderate grazing intensity (P<0.05). In experiment I, higher dry matter intake (DMI) values were obtained under continuous grazing, while in experiment II, there no differences between methods and intensities. CH4 emissions per animal and per day did not differ between treatments in both experiments (P>0.05), but when expressed in g CH4 kg-1 LWG emissions were, on average, 15.33% higher (P<0.05) for rotational grazing method, regardless of grazing intensity. Methane emissions per animal were not affected by the treatments applied. However, from system point of view, the continuous grazing method is more efficient, since lower methane emissions per kg of LWG, regardless of grazing intensity, were obtained. In Chapter III, were used only lambs. The methodologies of n-alkanes and fecal nitrogen, were applied through total collection with dung bags. In relation to n-alkanes, better results were obtained when using the pair C31:C32. For the methodology of fecal nitrogen, the equations proposed by Wang et al. (2009) and Azevedo (2011) were the best (P<0.05). The technique of fecal nitrogen proved to be more accurate than the use of n-alkanes, which overestimated the intake.