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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
861

How well can smallholders in the Amazon live: an analysis of livelihoods and forest conservation in cacao- and cattle-based farms in the Eastern Amazon, Brazil / Quão bem os agricultores familiares podem viver na Amazônia: uma análise de meios de vida e conservação florestal de pequenos produtores de cacau e gado na Amazônia Oriental, Brasil

Braga, Daniel Palma Perez 18 June 2019 (has links)
Since the first colonists were settled along the Transamazon highway in Eastern Brazilian Amazon, in the early 1970s, it has been hotly debated how to guarantee their livelihoods. Over time, cattle ranching became the priority option. However, with increasing awareness about the socio- environmental drawbacks of this production system, the search for less damaging production systems was intensified. Cacao (Theobroma cacao L.) based agroforestry systems present one of the most promising land use options because they conciliate attractive yields with ecosystems conservation. Independent from this, many smallholders (small-scale households) continue seeing cattle ranching as their dedication. Whether and to what degree, these perceptions and expectations are realistic is not known, as most studies concentrate on technical aspects so far. Against this backdrop, this study invested in better understanding what small-scale farmers dedicated to cacao and/or cattle can realistically expect regarding living standard of their family and the forest conservation as stability of their natural production basis. Along seven municipalities, we applied structured interviews to 95 households. As suggested by Principal Component Analysis, we used the responses about income and housing to define the economic well-being and calculate success levels for each household. We then calculated correlations and frequencies, and applied hypotheses tests (Spearman and Kruskall-Wallis). The data showed for nearly two thirds of the visited families an acceptable to good living standard (with an average income higher than 17,000 USD/year), but also, concerning weaknesses for the rest. The most relevant factors, positively related to success, were land size and level of technology. For successful households, the combination of social interactions, market niches and off-farm income showed relevancy. Cacao farmers could be as successful as cattle ranchers, regarding cacao (on suitable soils) generated at least six times higher income per hectare than cattle. When households adopted both systems the chances of success were even higher, but on the cost of more deforestation. With regards to forest conservation, agroforestry systems related to a diversification of the household economic basis, at best including the use of non-timber products of native trees, could be feasible alternatives for extensive cattle ranching. However, to diffuse such more complex production systems requires better policies and effective support grounded in a thorough institutional cooperation of multilateral stakeholders able to establish effective logistics and attractive markets for the related diverse array of products. Further studies should increase focus on the aspects of context and personal pathways of households, using complimentary descriptive methods beyond just quantitative evaluations. / Desde que os primeiros colonos foram assentados ao longo da rodovia Transamazônica, Amazônia Oriental, no início da década de 1970, se discute como garantir os meios de vida dessas famílias. Ao longo do tempo, a produção de gado se tornou a principal opção. No entanto, o aumento da preocupação com os danos ambientais promovidos pela pecuária extensiva tem chamado atenção para os sistemas agroflorestais com cacau (Theobroma cacao L.) como potencial alternativa, capaz de conciliar a produção com a conservação florestal. No entanto, agricultores familiares continuam aderindo à pecuária. Ainda existe pouco conhecimento científico para entender se, e em qual grau, essas percepções e expectativas são realísticas, pois grande parte das pesquisas têm focado em aspectos estritamente técnicos. Diante desta problemática, este estudo investigou o que os agricultores familiares, que produzem cacau e/ou gado, podem esperar em termos do padrão de vida a ser alcançado e da conservação florestal como estabilidade natural da sua base de produção. Ao longo de sete munícipios, nós aplicamos 95 entrevistas em roteiros estruturados. Conforme indicado pela Análise de Componentes Principais, usamos a renda e a moradia para definir o bem-estar econômico e calcular o nível de sucesso para cada família. Então, calculamos as correlações e frequências e aplicamos testes de hipóteses (Spearman e Kruskall-Wallis). Os resultados revelaram que aproximadamente dois terços das famílias puderam alcançar um padrão de vida em níveis aceitáveis ou bons (com renda média em torno de 17.000 dólares por ano), mas também foram destacadas dificuldades a serem consideradas. Os fatores mais relevantes, positivamente relacionados com o sucesso, foram o tamanho da terra e o nível de tecnologia. Para os agricultores bem-sucedidos, a combinação de interações sociais, nichos de mercado e renda externa demonstrou-se relevante. Produtores de cacau puderam ser tão bem-sucedidos quanto produtores de gado, considerando que o cacau (em solos favoráveis) gerou, no mínimo, seis vezes mais renda por unidade de área que o gado. Quando as famílias adotaram os dois sistemas de produção a chance de sucesso aumentou, consequentemente ao custo de maior desmatamento. Sobre a conservação florestal, os sistemas agroflorestais relacionados com a diversificação da renda familiar, no melhor dos casos incluindo o uso de produtos não-madeireiros de árvores nativas, poderia ser uma alternativa factível à pecuária extensiva. No entanto, para difundir tais sistemas produtivos mais complexos seria necessário melhores políticas e efetivo suporte fundamentado por meio de cooperações institucionais com parcerias multilaterais, capazes de estabelecer logísticas efetivas e mercados atrativos para uma diversa gama de produtos. Estudos posteriores deveriam ampliar o foco em aspectos de contexto e em trajetórias individuais, usando métodos qualitativos complementares, além de apenas avaliações quantitativas.
862

The investigation of different levels of vitamin A and its effects on animal performance, carcass traits, and the conversion rate of external fat color in cull-cows.

Parkinson, Jake T. January 2020 (has links)
No description available.
863

Relations spatiales entre les ressources biophysiques et les dynamiques d’occupation du sol du front pionnier en Amazonie orientale / Spatial relationships between biophysical resources and pioneer front dynamics in the Eastern Amazon

Osis, Reinis 18 November 2019 (has links)
L’Amazonie est soumise depuis plusieurs décennies à un changement rapide d’occupation du sol du fait de la déforestation, l’installation de systèmes de production agricole, notamment l’élevage bovin et plus récemment le soja. L’un des défis majeurs est de mieux comprendre la dynamique spatiale de ces processus et ses déterminants. Avec la réduction de la déforestation et l’évolution agraire sur les fronts pionniers, les ressources et contraintes naturelles semblent gagner en importance dans les choix opérés par les agriculteurs. L'objectif de la présente recherche est d'évaluer le rôle des facteurs biophysiques dans la dynamique de l’occupation du sol depuis 2000 et d’anticiper sur des futurs possibles dans un territoire amazonien d’ancien front pionnier, aujourd’hui consolidé, la municipalité de Paragominas. Nous avons mis en œuvre un modèle spatialement explicite, afin d’identifier la distribution spatiale des processus de changement en relation avec différents facteurs. Des entretiens réalisés avec des producteurs explicitent les logiques sous-jacentes. Les résultats montrent qu'il y a différentes logiques d'usage des ressources biophysiques, qui varient selon les types de production, la taille des exploitations, la distance aux routes et villages, et la distribution spatiale des ressources biophysiques dans l'exploitation. Elles évoluent au fil du temps, en fonction des productions et des avancées technologiques, et sont organisées dans l'espace. La mise en évidence de ces relations spatiales constitue une avancée significative pour représenter l'évolution de l’ usage des sols et constituer un appui dans la définition de politiques de développement territorial. / The Amazon has been subject to a rapid change in land use due to deforestation for several decades and more recently to the expansion of annual crops like soybeans. One of the major challenges is to understand better the spatial dynamics of these processes and its determinants. With the reduction of deforestation and the consolidation of pioneer fronts, natural resources and constraints seem to be gaining in importance in farmers' choices. The objective of this research was to assess the role of biophysical factors in land use dynamics since 2000 and to anticipate possible futures in a consolidated Amazonian pioneer frontier, the municipality of Paragominas. We implemented a spatially explicit model to identify the spatial distribution of change processes in relation to different factors. Interviews with farmers explain the underlying strategy. The results show different strategies for the use of biophysical resources according to the types of production, the size of the farms, the distance to roads and villages and the spatial distribution of biophysical resources in the farm. The strategies evolve over time, in relation to production and technological advances, and are organized in space. A better understanding of the importance of biophysical resources on the evolution of pioneer fronts through this type of method could provide support for land-use policies.
864

Comparative evaluation of different extenders of bull semen stored under different conditions

Raseona, Andrea Motswetla 16 July 2015 (has links)
MSCAGR / Department of Animal Science / Preservation of semen is an important process to ensure that semen quality is sufficient for use in assisted reproductive technologies. This study evaluated the effectiveness of three different extenders to preserve bull semen stored under different conditions, as an alternative to frozen-thawed semen straws used for artificial insemination. Semen samples were collected from two Nguni bulls using an electro-ejaculator and transported to the laboratory at 37 °C for evaluation. Pooled semen was first aliquoted into three extenders namely Triladyl, Ham’s F10 and M199 at a dilution ratio of 1:4 (semen:extender), and then stored at controlled room temperature 24 °C. Secondly pooled semen was aliquoted into four groups of Ham’s F10 extender and diluted at a ratio of 1:4, then stored at 24 °C, 17 °C, 12 °C and 5 °C respectively. Sperm motility rates were analysed after 0, 24, 48 and 72 hours. Morphology, viability and sperm DNA fragmentation were analysed after 72 hours. The study was replicated four times and data was analysed by ANOVA. Triladyl had higher sperm viability rate and total motility rate for 72 hours (P<0.01). However, Ham’s F10 had higher progressive motility rate as compared to the other extenders. There was no significant difference (P<0.01), in the viability rate between Ham’s F10 and M199. No significant difference was also observed in total sperm abnormalities (absent tails, coiled tails and bent tails), except for reacted acrosomes (P>0.05), between the two Nguni bulls. Lower temperatures than 24 °C influenced sperm motility and viability in Ham’s F10. There was no significant difference in sperm DNA fragmentation rates (P<0.01), between all the four storage temperatures which indicated that temperature did not have an influence on sperm DNA fragmentation. In conclusion, bull semen can be preserved in Triladyl or Ham’s F10 and M199 culture media stored at 24 °C and stay alive for 72 hours. Triladyl proved to be the best suitable extender showing higher sperm viability and total motility rates as compared to Ham’s F10 and M199. Lower temperatures than 24 °C noticeably decreased sperm motility and viability in Ham’s F10 culture medium.
865

Effects of ovulation-inducing drugs on pregnancy rates of cattle in rural areas after synchronized oestrus and artificial insemination

Nethengwe, Luvhengo Dakalo 12 February 2016 (has links)
Institute for Rural Development / MRDV
866

Ecology and diet of the caracal (Caracal caracal) on lethal and non-lethal control farms in the Karoo

Jooste, Erin Cecilia January 2020 (has links)
>Magister Scientiae - MSc / Human-wildlife conflict is an ongoing issue worldwide. Within South Africa, human-carnivore conflict (HCC) as a result of carnivore depredation on small-livestock causes large-scale losses, and promotes the use of predator management tools by farmers. Despite being one of the major offenders involved in HCC, caracals, and their ecology in particular, are understudied. This is mainly due to high levels of persecution, coupled with their elusive nature. Within the Karoo region of South Africa, pastoralists make use of large-scale lethal predator controls in an attempt to remove the offenders, or non-lethal predator controls to protect livestock and deter predators. However, the effects of these various predator control techniques on caracal ecology have not been widely tested. Therefore, the aims of this thesis were, firstly, to assess caracal diet on lethal and non-lethal treatment farms in the Karoo; secondly, to investigate the drivers of caracal habitat selection on a non-lethal farm in the Karoo; and finally, to evaluate caracal activity patterns on the non-lethal farm. To do this, I made use of two non-invasive techniques (i.e. scat analysis and camera trapping). Caracals appeared to favour natural prey across all sites, with livestock remains only found in scats collected at the lethal treatment farm. Caracals had the broadest dietary breadth on the non-lethal treatment site, and the narrowest on the lethal treatment site. The main components of caracal diet included small mammals, lagomorphs, rock hyraxes (Procavia capensis), wild ungulates and arthropods. Caracal habitat selection was explained by resource dispersion and environmental features Interestingly, the presence of livestock was not a major consideration in caracal habitat selection. Caracals were mainly nocturnal but became increasingly crepuscular during winter. In addition, caracal activity overlapped significantly with black-backed jackals (Canis mesomelas), lagomorphs and common duikers (Sylvicapra grimmia). Caracals showed plasticity in their activity patterns based on seasonal temperature fluctuations, and partially human avoidance. This study contributes to understanding how caracal ecology differs on differently managed livestock farms. Throughout this study, the importance of both a natural prey base, as well as natural lands to caracal survival have been revealed. These findings can contribute to caracal conservation in HCC areas.
867

A statistical approach to understand Crimean-Congo hemorrhagic fever prevalence in Pakistan

Karim, Abdul January 2020 (has links)
Geographically, Pakistan is in the western part of south Asia at about 24-37 °N latitudes and62-75 °E longitudes. Livestock and agriculture are two major sectors in Pakistan and play animportant role in the country economy.The tick infestation in livestock is not only devastating for animals and their products but alsobecome the cause of transmission of pathogens into humans. Crimean Congo fever (CCHF) isa viral tick-borne fatal disease. The dissemination of ticks and amplification of Crimean Congofever (CCHF) pathogen throughout the tick-animals-tick cycle, increases risk of transmissionto humans many times. In Pakistan, cases are reported in all areas, particularly those areaswhich lie on the border to CCHF endemic countries. There is a high prevalence of CCHF inboth Baluchistan and Khyber Pakhtunkhwa regions. Baluchistan is bordering with Afghanistanand Iran and Khyber Pakhtunkhwa with Afghanistan. Linear regression analysis revealed apositive significant association of high level of CCHF cases in livestock, with camels, goatsand sheep. The literacy rate is negatively significantly corelated with the numbers of cases.Statistical analysis of border effect revealed a high positive significant correlation of CCHFprevalence in areas near to borders. Both Baluchistan and Khyber Pakhtunkhwa (KPK) haslow literacy rate than other regions of Pakistan. Islamabad (capital city) has a higher literacyrate than all other regions but there is still a high CCHF prevalence. This is not only becauseof high population density but people from other regions, particularly from Baluchistan andKPK come here for animals selling or to seeking medical facilities in the large city hospitals.The study gives a proof that illiteracy and borders are the major respondent factors in theCCHF incidences and prevalence in an area. There is a need to raise awareness about ticksand tick-borne disease in the public and establishment of monitoring system across the bordersto prevent the spread of CCHF virus.
868

Produtividade de forragem do milho em função de atributos físicos de um latossolo vermelho distrófico sob plantio direto /

Lima, Ronaldo Cintra. January 2007 (has links)
Resumo: A cultura do milho apresenta sistema radicular com alto potencial de desenvolvimento. Assim sendo, os atributos físicos do solo são de extrema importância à sua produtividade, uma vez que em condições adversas podem dificultar a penetração das raízes, e conseqüentemente limitar o adequado aproveitamento dos nutrientes e da água disponível. No ano de 2005, na Fazenda Bonança (Agropecuária Dahma), município de Pereira Barreto (SP), Brasil (20o40'12'' latitude S; 51o01'50'' longitude W), foi instalado o presente ensaio em uma área irrigada por pivô central e manejada no sistema de integração agricultura-pecuária, com plantio direto de milho sobre brachiária. Os atributos analisados foram: produtividade de forragem do milho (MSF), macroporosidade (MA), microporosidade (MI), porosidade total (PT), densidade (DS), resistência à penetração (RP) e umidade gravimétrica (UG) de um Latossolo Vermelho Distrófico (Acrustox Háplico), nas profundidades 1 (0-0,10 m), 2 (0,10- 0,20 m) e 3 (0,20-0,30 m). O objetivo foi estudar a variabilidade e as correlações lineares e espaciais entre os atributos da planta e do solo, visando selecionar um indicador da qualidade física do solo de boa representatividade para a produtividade da forragem. Foi instalada a malha geoestatística para a coleta dos dados do solo e da planta, contendo 125 pontos amostrais, numa área de 2500 m2 e declive homogêneo de 0,025 m/m. No geral, os atributos estudados, além de não terem revelado distribuição aleatória, apresentaram variabilidade entre baixa e muito alta. Seguiram padrões espaciais claramente definidos, com alcances da dependência espacial entre 6,6 e 31,1 metros. Assim, o maior alcance que poderá assegurar extrema semelhança em magnitude para qualquer atributo estudado, e que poderá alimentar os pacotes computacionais direcionados à ...(Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Corn crops have great potential of root development. Therefore, the physical soil features are of great importance to the crops yields, as the unfavorable conditions may hinder root penetration and, thus, limit the nutrient and available water uptake. This experiment was established in 2005, on Bonança Farm (Dahma Agrarian), in Pereira Barreto (SP), Brasil (20°40'12'' latitude S; 51°01'50'' longitude W), in an area which was irrigated with centerpivot and managed according to the crop-livestock integration system, with corn under the notillage on Brachiaria. The analyzed characteristics were: corn forage yield (CFY), macroporosity (MA), microporosity (MI), total porosity (TP), density (SD), penetration resistance (PR) and gravimetric moisture (GM) of a Typic Hapludox in the depths of 1 (0- 0.10 m), 2 (0.10-0.20 m) and 3 (0.20-0.30 m). The objective was to study the variability and the linear and spatial correlations between the plant and the soil features, aiming at selecting an indicator for the physical quality of the soil which represents forage yield. A geostatistical mesh was installed for data collecting regarding the soil and the plant, with 125 sampling stations, in an area of 2500 m2 and homogeneous slope of 0.025 m/m. On the whole, the evaluated features, besides not showing random distribution, showed variability between low and very high. Spatial patterns which were clearly defined with the ranges of spatial dependence between 6.6 and 31.1 m have been followed. Therefore, the greatest range which can assure extreme magnitude similarity for any of the studied features, and which will be able to feed the software designed for precision farming, must be of 31.1 m. Despite the fact that the simple linear correlation between CFY and MI2 was low, it was extremely significant. However, from the spatial point of view, there has been high inverse correlation...(Complete abstract click electronic access below) / Orientador: Luiz Malcolm Mano de Mello / Coorientador: Morel de Passos e Carvalho / Banca: Marcelo Andreotti / Banca: Rubens Siqueira / Mestre
869

Impact of Metabolic Stress, Microbiome, and Lymph Node Colonization on <i>Salmonella</i> Shedding in Dairy Cattle

Munoz Vargas, Lohendy M. 11 August 2017 (has links)
No description available.
870

Artificial Intelligence in Agriculture : Opportunities and Challenges

Casten Carlberg, Carl Johan, Jerhamre, Elsa January 2021 (has links)
Artificial Intelligence (AI) is increasingly used in different parts of society for providing decision support in various activities. The agricultural sector is anticipated to benefit from an increased usage of AI and smart devices, a concept called smart farming technologies. Since the agricultural sector faces several simultaneous challenges, such as shrinking marginals, complicated pan-European regulations, and demands to mitigate the environmental footprint, there are great expectations that smart farming will benefit both individual farmers and industry stakeholders. However, most previous research focuses only on a small set of characteristics for implementing and optimising specific smart farming technologies, without considering all possible aspects and effects. This thesis investigates both technical and non-technical opportunities and hurdles when implementing AI in Swedish agricultural businesses. Three sectors in agriculture are scrutinized: arable farming, milk production and beef production. As a foundation for the thesis, a literature review revises former research on smart farming. Thereafter, an interview study with 27 respondents both explores the susceptibility and maturity of smart farming technologies and provides examples of technical requirements of three chosen applications of AI in agriculture. Findings of the study include a diverse set of aspects that both enable and obstruct the transition. Main identified opportunities are the importance smart farming has on the strategic agendas of several industry stakeholders, the general trend towards software technology as a service through shared machinery, the vast amount of existing data, and the large interest from farmers towards new technology. Contrasting, the thesis identifies main hurdles as technical and legislative challenges to data ownership, potential cybersecurity threats, the need for a well-articulated business case, and the sometimes lacking technical knowledge within the sector. The thesis concludes that the macro trend points towards a smart farming transition but that the speed of the transformation will depend on the resolutions for the identified obstacles.

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