Background: The success of different species of ruminants in the colonization of a diverse range of environments is due to their ability to digest and absorb nutrients from cellulose, a complex polysaccharide found in leaves and grass. Ruminants rely on a complex and diverse microbial community, or microbiota, in a unique compartment known as the rumen to break down this polysaccharide. Changes in microbial populations of the rumen can affect the host's development, health, and productivity. However, accessing the rumen is stressful for the animal. Therefore, the development and use of alternative sampling methods are needed if this technique is to be routinely used in cattle breeding. To this end, we tested if the fecal microbiome could be used as a proxy for the rumen microbiome due to its accessibility. We investigated the taxonomic composition, diversity and interrelations of two different GIT compartments, rumen and feces, of 26 Nelore (Bos indicus) bulls, using Next Generation Sequencing (NGS) metabarcoding of bacteria, archaea and ciliate protozoa. Results: We identified 4265 Amplicon Sequence Variants (ASVs) from bacteria, 571 from archaea, and 107 from protozoa, of which 143 (96 bacteria and 47 archaea) were found common between both microbiomes. The most prominent bacterial phyla identified were Bacteroidetes (41.48%) and Firmicutes (56.86%) in the ruminal and fecal microbiomes, respectively, with Prevotella and Ruminococcaceae UCG-005 the most relatively abundant genera identified in each microbiome. The most abundant archaeal phylum identified was Euryarchaeota, of which Methanobrevibacter gottschalkii, a methanogen, was the prevalent archaeal species identified in both microbiomes. Protozoa were found exclusively identified in the rumen with Bozasella/ Triplumaria being the most frequent genus identified. Co-occurrence among ruminal and fecal ASVs reinforces the relationship of microorganisms within a biological niche. Furthermore, the co-occurrence of shared archaeal ASVs between microbiomes indicates a dependency of the predominant fecal methanogen population on the rumen population.

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Livestock production is important for food security, nutrition, and landscape maintenance, but it is associated with several environmental impacts. To assess the risk and benefits arising from livestock production, transparent and robust indicators are required, such as those offered by life cycle assessment. A central question in such approaches is how environmental burden is allocated to livestock products and to manure that is re-used for agricultural production. To incentivize sustainable use of manure, it should be considered as a co-product as long as it is not disposed of, or wasted, or applied in excess of crop nutrient needs, in which case it should be treated as a waste. This paper proposes a theoretical approach to define nutrient requirements based on nutrient response curves to economic and physical optima and a pragmatic approach based on crop nutrient yield adjusted for nutrient losses to atmosphere and water. Allocation of environmental burden to manure and other livestock products is then based on the nutrient value from manure for crop production using the price of fertilizer nutrients. We illustrate and discuss the proposed method with two case studies.

Stream metabolism is affected by both natural and human-induced processes. While metabolism has multiple implications for ecological processes, relatively little is known about how metabolic rates are influenced by land use in tropical streams. In this study, we assessed the metabolic characteristics and related environmental factors of six streams located in a transition area from Cerrado to Atlantic Forest (São Carlos/Brazil). Three streams were relatively preserved, while three were flowing through more agriculturally and/or urban impacted watersheds. Surface water samples were analyzed for biological and physico-chemical parameters as well as discharge and percentage of canopy cover. Metabolism was determined through the single-station method to estimate gross primary production (GPP), ecosystem respiration (ER) and net ecosystem production (NEP) with BAyesian Single-station Estimation (BASE). Nutrient concentrations tended to be higher in impacted versus preserved streams (e.g., average total phosphorus between 0.028-0.042 mg L-1 and 0.009-0.038 mg L-1, respectively). Average canopy cover varied between 58 and 77%, with no significant spatial or seasonal variation. All streams were net heterotrophic (ER exceeded GPP) in all sampling periods. GPP rates were always lower than 0.7 gO2 m-2 d-1 in all streams and ER varied from 0.6 to 42.1 gO2 m-2 d-1.  Linear Mixed-Effect models showed that depth, discharge, velocity and total phosphorus are the most important predictors for GPP. For ER, depth, velocity and canopy cover are significant potential predictors. Canopy cover was the main light limiting factor and influenced stream metabolism. Our findings reinforced the concepts that shifts in the shading effect provided by vegetation (e.g., through deforestation) or changes in discharge (e.g., through land use conversion or water abstractions) can impact freshwater metabolism. Our study suggests that human activities in low latitude areas can alter tropical streams’ water quality, ecosystem function, and the degree of riparian influence. Our data showed that tropical streams can be especially responsive to increases of organic matter inputs leading to high respiration rates and net heterotrophy, and this should be considered to support management and restoration efforts.

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). Os Estados com baixas produtividades para as culturas de milho e soja apresentaram pegadas hídricas maiores. O cálculo da pegada demonstrou que a gestão hídrica da cadeia produtiva de suínos não pode abordar somente a unidade produtiva, devendo inserir as cadeias agrícolas que se relacionam com ela.Palavras-chave: água, crescimento-terminação, dieta. ABSTRACT. Water footprint of pigs slaughtered in the states of south-centralBrazil. The aim of this study was to calculate the water footprint of pigs slaughtered in 2008 in each state of south-central Brazil. The calculation of water footprint considered water consumed in grain production (corn and soybean), drinking water and washing water. Rio Grande do Sul was the state with the largest water footprint (2.702 km ). States with low yields of corn and soybeans had higher water footprint. Calculations show that water management in swine production cannot address only the farm; it should include related agricultural supply chains.Keywords: water, growing-finishing, diet. IntroduçãoA inserção do manejo ambiental nas produções pecuárias brasileiras é prática recente e ainda limitada a algumas produções, notadamente a suinocultura, bovinocultura de corte e carcinocultura por estas gerarem importantes produtos cárneos no conjunto de produtos exportados pelo país, além de ameaçarem a preservação de biomas e ecossistemas sensíveis. No entanto, mesmo nestas cadeias produtivas o manejo se limita, muito mais, a um conjunto de intenções, do que práticas no dia-a-dia produtivo das unidades de produção. Essas intenções são maiores ou menores de acordo com o momento produtivo, ou seja, em momentos de crise econômica as ações são paralisadas.Mas essa situação deve ser mudada, pois os mercados consumidores internos e externos e os novos conceitos e as exigências como sistemas de rastreabilidade e certificação, produtos com denominação de origem, boas práticas de produção, entre outros, exigem que o manejo produtivo seja documentado e utilizem-se indicadores a fim de mensurar a eficiência ambiental da produção. As produções pecuárias brasileiras devem promover mudanças em sua situação ambiental, melhorando sua relação com os recursos naturais e demonstrando que o desenvolvimento com sustentabilidade é uma meta a ser alcançada.A demanda por produtos animais aumentou significativamente nas últimas décadas e é esperado um crescimento ainda maior, particularmente, nos países em desenvolvimento, aumentando assim a pressão sobre os recursos naturais (DELGADO et al., 1999;PENNING DE VRIES et al., 1997). O aumento projetado da demanda de água pela pecuária mundial para o ano de 2025 é de 71%, e grande parte deste ocorrerá nos países em desenvolvimento (BRUINSMA, 2003; DELGADO et al., 1999;ROSEGRANT et al., 2002).A relação da atividade pecuária com a gestão dos recursos hídricos gera desafios vinculados a

Milk production is important in South American countries being based mainly on grazing systems. Dairy slurry management has become an important issue in these production systems because of the large volumes produced and the environmental effects. Thus, manure management regulations are emerging in the region. This research aims to identify priorities for management strategies and technology transfer by assessing perceptions, needs and barriers toward dairy manure management by stakeholders in South American countries. A questionnaire was prepared and distributed in Spanish and Portuguese in different formats: on paper and online (PDF format and SurveyMonkey TM platform) between March 2015-November 2017. It was divided into two sections, the first addressed issues related to water quality and pollution, odor generation, fertilizer value, pathogens impact and biogas production. Responses were measured across a standard 5-point Likert type scales. Section two addressed needs and hindrances concerning about manure application. A total of 593 surveys were completed: Argentina (n = 308, 52%), Brazil (n = 217, 37%) and Chile (n = 68, 11%). The majority of respondents were dairy farmers (31%), professional advisors and consultants (29%) and representatives of public institutions and researchers (31%). Some differences appear according the country. Overall, a large majority perceive that manure is a good fertilizer (91%), also they believe that it contributes to pathogen's transmission and groundwater and shallow aquifers 'contamination. Stakeholders (60%) perceived biogas production as a good option for manure treatment. Most of respondents (79%) would use manure to replace mineral fertilizers, with little differences between countries (Argentina 79%, Brazil 80% and Chile 68%). The most selected needs were: a management handbook, increased investment in equipment and technologies and better access to laboratory analysis. The most chosen barriers were: cumbersome management, lack of knowledge and of specific laws, with differences between countries and respondents. The survey showed interest in dairy manure management as a source of nutrients for grassland and crops, especially among farmers and advisors whom requested Herrero et al.South American Dairy Manure Management Perceptions guidelines for responsible management. Policymakers and stakeholders should focus on promoting manure reuse on dairy farms through incentives, technologies and/or appropriate strategies, in order to improve nutrient use and reduce pollution to the wider environment.