• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 33
  • 7
  • 4
  • 3
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • Tagged with
  • 57
  • 57
  • 15
  • 11
  • 9
  • 9
  • 8
  • 7
  • 7
  • 7
  • 7
  • 7
  • 6
  • 6
  • 6
  • 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.
41

Listeria monocytogenes : farm and dairy studies /

Waak, Elisabet, January 2002 (has links) (PDF)
Diss. (sammanfattning) Uppsala : Sveriges lantbruksuniv., 2002. / Härtill 5 uppsatser.
42

Availability of potassium to clover and grass from soils with different potassium fertilization histories /

Salomon, Eva, January 1900 (has links) (PDF)
Diss. (sammanfattning) Uppsala : Sveriges lantbruksuniv. / Härtill 5 uppsatser.
43

Unique decision making with focus on information use : the case of converting to organic milk production /

Lunneryd, Daniel, January 2003 (has links) (PDF)
Diss. (sammanfattning). Uppsala : Sveriges lantbruksuniv., 2003.
44

Há espaços para melhora no setor leiteiro? Uma análise de fronteira estocástica de produção e regressão quantílica utilizando dados do Censo Agropecuário 2006 (IBGE) / Is there room for improvement in the dairy sector? A stochastic production frontier and quantile regression analysis using data from the 2006 agricultural census (IBGE)

Ricardo Alves de Brito 25 August 2016 (has links)
Ao longo dos últimos anos tem se observado no mundo uma expansão do setor leiteiro. Parte dessa expansão se deve a novas tecnologias que foram adotadas nas últimas décadas, mas também ocorreu por causa da queda, ou da anulação de barreiras comerciais. Contudo, notou-se também uma queda no número de fazendas leiteiras. Sendo o leite uma commodity os preços seguem as oscilações de mercado - oferta e demanda - e nenhum dos agentes possui poder para influenciar nos preços de compra e venda dessa mercadoria. Como os boletins do CEPEA mostram, os preços no ano passado têm-se mantido abaixo da média histórica, referente à última década, mas os termos de troca com relação a quantidade de litros de leite para se comprar insumos e defensivos se mantêm em patamares estáveis com tendência de alta. Tendo em vista esse problema, surge a necessidade de buscar compreender melhor como funciona o sistema de produção do setor leiteiro. Este trabalho satisfatoriamente conseguiu detectar através das fronteiras estocásticas de produção simples - leite como único produto de saída - e multi-output - leite e outros produtos animais existentes nas fazendas - além da regressão quantílica para análise de quantis variados da produção de leite, quais os insumos utilizados pelos produtores que oferecem melhores retornos para sua produção bem como analisar fatores de eficiência (BATTESE, COELLI; 1995; CHIDMI; SOLÍS; CABRERA, 2011). Os resultados apresentados apontam para a necessidade de se levar em consideração a inter-relação entre os insumos considerados - função de produção translog - e identificaram os insumos referentes ao capital - quantidade de vacas ordenhadas e gastos com máquinas e equipamentos - e ao trabalho - gastos com salários - como principais insumos da atividade pecuária. Os gastos com medicamentos animais, com energia elétrica e a área disponível para a atividade pecuária se mostraram contraproducentes indicando mau uso ou uso excessivo desses fatores, além de ressaltar a importância do capital na pecuária. Em geral, para quase todos os modelos testados, a produção leiteira apresentou retornos constantes à escala e nível de eficiência em torno de 88% em média para as fronteiras estocásticas e 90% para as estimativas feitas com regressão quantílica. Entre os fatores de eficiência identificados estão a capacidade de armazenamento de silos e tanques de refrigeração para o leite e a margem bruta líquida obtida com a atividade. Os fatores de ineficiência identificados são a prática de queimadas e o percentual de mulheres na administração das unidades produtivas. Com relação aos variados modelos estimados percebeu-se, em suma, a necessidade de se intensificar a produção pecuária e de melhorar a infraestrutura das fazendas. / Over the past few years it has been observed in the world an expansion of the dairy industry. Part of this expansion is due to new technologies that have been adopted in recent decades, but also because of the fall, or the annulment of trade barriers. However, it has also been noted a drop in the number of dairy farms. Being a commodity, milk prices follow the market oscillations - supply and demand - and none of the agents has enough power to influence buying and selling prices of this commodity. As the CEPEA bulletins show, prices last year have remained below the historical average for the last decade, but the terms of trade regarding the amount of liters of milk to buy inputs and pesticides at levels remain stable with uptrend. In view of this problem, there is the need to get a better understanding of how the dairy sector production system works. This work satisfactorily managed to detect, through the single-output stochastic production frontier method - value of milk production as output - and multi-output - value of milk and other existing animal products at the farms - besides quantile regression analysis for multiple production quantiles, which inputs used by farmers offer the best outcome for their production as well as analyzing efficiency factors (BATTESE; COELLI, 1995; CHIDMI; SOLÍS; CABRERA, 2011). The estimated results pointed to the need of considering the interrelation of considered inputs - translog production function - and identified the capital related inputs - quantity of milked cows and expenditure on machinery and equipment - and work related inputs - expenditure on wages - as main production inputs. Expenditure on animal drugs and on electricity and the area available for livestock activity proved counterproductive indicating misuse or overuse of these factors, in addition to emphasizing the importance of capital in livestock. In general, for most of the tested models, dairy production showed constant returns to scale and an average efficiency level of 88% for stochastic frontier models and 90% for estimates done using quantile regression. Among the identified efficiency factors are the storage capacity of silos and cooling tanks for milk and the net gross margin with activity. The identified inefficiency factors are the practice of burning and the percentage of women in the management of production units. With regard to various models estimated it was realized, in short, the need to intensify livestock production and to improve the infrastructure of the farms.
45

Airborne microbiota and related environmental parameters associated with a typical dairy farm plant

Mokoena, Kingsley Katleho January 2013 (has links)
Thesis (M. Tech. (Environmental health: Food safety )) - Central university of Technology, Free State, 2013 / Food processing plants and agricultural environments have a long-standing history of being known to provide a conducive environment for the prevalence and distribution of microorganisms which emanate as a consequence of activities undertaken in such premises. Microorganisms in the aforementioned environments may be found in the atmosphere (airborne), and/or on food contact surfaces. Airborne microorganisms from food handlers and in food products and raw materials (as part of bioaerosols) have in the past been implicated as having a potential to cause adverse health effects (especially in indoor environments) and therefore also to have economic implications. Recently their effect on food safety has received increased interest. The recent international interest in bioaerosols in the food industry has played a role in rapidly providing increased understanding of bioaerosols and their effects in different food processing environments. However, there is still a lack of research on the actual impact of bioaerosols over time in most of the food premises especially in Southern Africa and other developing countries. The overall purpose of this dissertation was to assess possible microbial contaminants and the role of selected environmental parameters on these microbes at a dairy farm plant in central South Africa. In relation to the purpose of the study, the objectives of this dissertation were to investigate and establish the food handler’s food safety knowledge, attitude, behaviour and practices. The sub-objective was to investigate the prevalence and distribution of microbial contaminants (both airborne and food contact surface populations), and concomitant environmental parameters. The microbe isolates from both investigations (i.e. air samples and food contact surfaces) were identified to strain level using matrix-assisted laser desorption ionization – time of flight mass spectrometry (MALDI-TOF MS). The findings of this study in relation to food handlers’ food safety knowledge, attitude, behaviour and practices indicated a dire need for training of employees as well as improved health and hygiene measures as emphasised by some of the identified strains. The environmental parameters (both indoor and outdoor) were similar, with no relationship established between airborne microbes’ prevalence and environmental parameters. The samples of the airborne microbial populations in both indoor and outdoor environments were similar. Airborne microbial counts at the dairy farm plant over the entire duration of the study ranged between 1.50 x 101cfu.m-3and 1.62 x 102cfu.m-3. Microbial counts on food contact surfaces ranged between 2.50 x 102 cfu.cm-2 and 1.10 x 105 cfu.cm-2 over the entire duration of the study. A wide variety of microorganisms (from air and food contact surfaces) such as the Gram-positive bacteria, Gram-negative bacteria, as well as fungi were present at the dairy farm plant. A number of the isolated genera have previously been associated with agricultural environments whilst others are associated with hospital environments. The positively identified strains were from genera such as Aeromonas, Arthrobacter, Candida, Pseudomonas, Pantoea, Citrobacter, Staphylococcus, Bacillus, Escherichia, Rhodococcus and Rhodotorula, amongst others. The isolation of microorganisms associated with food spoilage and foodborne disease outbreaks, which are known as indicator organisms such as Escherichia coli, Staphylococcus and Bacillus from both air and surface samples, signified possible faecal contamination and could be attributed to poor health and hygiene practices at the dairy farm plant. Despite the isolation of microorganisms associated with food spoilage and foodborne disease outbreaks, the isolation of microorganisms not usually associated with the food processing industry (usually associated with hospital environments) was an enormous and serious concern which suggested a need for further investigations at dairy farm plants as the implications of these pathogenic microorganisms in food is not known. The isolation of similar microorganisms from both the air samples and surface swabs suggests that airborne microbes have a potential of settling on food contact surfaces, therefore having a potential to contaminate dairy products which are known to be more prone to contamination and which, because of their nutritional status, serve as a good substrate for the growth of microorganisms.
46

Factors influencing the bacteriological quality of raw milk produced on dairy farms in Central South Africa

Louw, Celmarie January 2013 (has links)
Thesis (M. Tech. (Environmental health)) - Central University of technology, Free State, 2013 / Introduction Dairy farms in central South Africa produce a substantial amount of milk, which is sold in Bloemfontein, Free State. Large volumes of unpasteurized (raw) milk is collected on the dairy farms, which undergoes further processing before it reaches the consumer at the end of the production line. There is a large proportion of the population that, in most cases unknowingly, consumes raw milk that has bacterial counts substantially higher than legal standards. Poor quality unpasteurized milk is either sold as fresh milk in the informal market, or as dairy products, such as cheese, manufactured from unpasteurized milk. Consumers are therefore, in most cases, unaware of the poor quality dairy products they consume. Milk quality is usually assessed in terms of bacterial content, which include Escherichia coli, coliforms and total bacterial count. The bacterial quality of milk is influenced by a number of factors, including farming practices, structural design of the milking shed, herd health and quality of water used in the dairy. If the highest level of hygiene practices is maintained, contamination of the milk by pathogenic microorganisms will be controlled, however, any drop in the vigilance of hygiene practices could result in unacceptable high levels of pathogenic microorganisms resulting in poor quality raw milk. Poor quality raw milk will inevitably result in poor quality pasteurized milk, containing unacceptably high levels of pathogenic organisms, which will eventually reach the consumer. Objectives The objectives of this study were to assess the quality of milk and influencing factors of milk produced on 83 dairy farms that supply milk intended for further processing to the greater Mangaung region, Central South Africa. Influencing factors investigated included, water quality and hygiene of milk contact surfaces, namely pulsator surfaces and milk pipeline surfaces. Methods Standard sampling procedures were followed when milk was sampled from bulk milk tanks, water at the point of use in the dairy, as well as collection of surface swabs. Escherichia coli, coliforms, total bacterial counts and somatic cell counts in milk were determined in terms of the regulations relating to milk and dairy products, and for water in terms of drinking water standards. These data were analysed and the factors that directly influence bacterial quality of milk were identified. Results 93% of the dairy farms displayed E. coli in their bulk milk containers, which did not comply with the legal standard. For coliforms, 86% of the milk samples did not comply with the legal standard. The total bacterial count of 85% of the milk samples did comply with the legal standard. The somatic cell count of 42% of the milk samples did not comply with the legal standard. The pulsator surfaces as well as the milk pipeline surfaces of 13% of the dairy farms displayed the presence of E. coli. 80% of the pulsator surfaces and 78% of the milk pipeline surfaces did comply with the legal standard pertaining to coliforms. The total bacterial count of pulsator surfaces revealed that 19% complied, whereas 29% of the milk pipeline surfaces complied with the legal standard. The water data further revealed that 31% of the dairy farms contained E. coli in the water used in the dairies. 63% of the dairy farms contained more than the allowable number of coliforms in their water. Chi-square tests revealed significant differences (p > 0.05) between the presence or absence of E. coli in milk and water; the presence or absence of E. coli in milk and milk pipeline surfaces; the presence or absence of E. coli in milk and pulsator surfaces and the presence or absence of E. coli in milk and the positioning of the cows in the milking shed. When milk quality indexes were calculated for all the farms, only four farms were classified with excellent milk, the remainder were all classified as producing poor quality milk. The hygiene quality indexes revealed that the hygiene practices on all the farms were not up to standard. Discussion and conclusion The study revealed that the milk produced for commercial processing and distribution in the greater Mangaung region of central South Africa was of poor quality. It is often mistakenly believed that the pasteurization process will remove all microorganisms from milk. As this is not the case, it is of major concern that milk delivered commercially is not of acceptable quality. Furthermore, it could be concluded that the quality of milk products from raw milk were also probably not of acceptable quality. The results further revealed that the possible contributing factors to the poor quality milk produced by the 83 commercial dairy farms were; poor quality water used in dairy sheds and contaminated milk contact surfaces. From this study it could be concluded that the overall status of milk production on the 83 commercial dairy farms studied, did not meet the standards required for milk quality, water quality and hygiene practices.
47

A Bayesian approach to dynamic efficiency and productivity measurement

Skevas, Ioannis 06 February 2017 (has links)
No description available.
48

Avaliação da gestão de unidades produtoras de leite da microrregião de Franca SP / Evaluation of the management of dairy production farms in the micro region of Franca SP

Ribeiro, Simone Goldman Batistic 10 August 2017 (has links)
O uso de ferramentas de gestão favorece a eficiência de um negócio, uma vez que por meio da coleta de dados produtivos e financeiros um empresário consegue tomar as melhores decisões. Os bovinocultores de leite podem obter melhores resultados nos seus negócios ao coletar e analisar dados. Porém o uso de ferramentas de gestão por esta categoria de produtores se mostra incipiente por uma série de razões. Pesquisas sobre gestão em propriedades produtoras de leite no Brasil consideram, principalmente, aspectos produtivos e financeiros, não estudando outras ferramentas de gestão, como o planejamento. A microrregião de Franca, Estado de São Paulo, apresentou queda de 12% em número de propriedades produtoras de leite entre 2007 e 2015, porém houve aumento de 37% na produção. Este trabalho teve como objetivo identificar se a gestão ou a falta dela influencia os produtores de leite na tomada de decisão de continuar ou sair da atividade. Foi realizado levantamento bibliográfico sobre a gestão em propriedades produtoras de leite e encontrou-se que o empreendedorismo, o controle dos aspectos produtivos, a resiliência, os arranjos produtivos horizontais foram importantes na análise dos melhores resultados. Outro achado nos trabalhos estudados foi que os produtores de leite consideram fatores não econômicos ao tomarem decisões. Foram realizadas 25 entrevistas qualitativas com produtores de leite, nas quais se avaliou se a gestão era prática dos respondentes, quais ferramentas eram utilizadas por eles e se a gestão era decisiva para que eles continuassem na atividade. O estudo também objetivou saber quais eram os fatores não econômicos levados em consideração por eles ao decidirem expandir a atividade, manter como está ou sair da mesma. Ao avaliar as respostas, encontrou-se que o uso de ferramentas de gestão vai tornando-se mais sofisticado conforme aumenta o nível de escolaridade dos produtores. Os produtores de leite levavam em consideração fatores não econômicos (valores) no momento de tomar uma decisão, tais como: legado, tradição (herança), gosto pela vida no campo, gostar da atividade leiteira, independência etc. Eles consideravam, ademais, fatores econômicos, tais como: venda de animais, pagamento mensal e lucratividade. Ao que parece, o uso de ferramentas de gestão não teve influência direta na tomada de decisão do produtor em continuar na atividade, uma vez que produtores que não utilizavam qualquer ferramenta demonstraram interesse na continuidade, muito embora os produtores que utilizavam ferramentas de gestão eram os mais eficientes. / The use of management tools favors the efficiency of a business, once production and financial data can be used for the entrepreneur to make better choices. Dairy farmers can get better results in their business by collecting and analyzing data, but the use of management tools by dairy farmers is different when there´s a comparison between the farmers, due to a number of reasons. Researches on management in dairy farmers in Brasil mainly consider productive and financial aspects and there´s a lack of studies on management tools, such as planning. There was a decrease of 12% in number of dairy farms in micro region of Franca, São Paulo State, between 2007 and 2015, but, at the same time, there was a 37% increase in production. This work had as objective to identify if the management or the lack of it influences the dairy farmers in the decision making to continue or leave the activity. It was made a survey about management practices on dairy farmers at the literature and it was found that entrepreneurship, control of productive aspects, resilience, and horizontal productive arrangements were important in the analysis of the best results. Another finding in these studies was that dairy farmers consider non-economic factors when making decisions. 25 qualitative interviews were conducted with dairy farmers in which it was evaluated whether the management was practiced by the respondents, which tools were used by them and if management was decisive for them to continue in the activity. This study also objected to know what were the non-economic factors taken into account by them when deciding to expand the activity, to maintain as it is or to leave. When evaluating the answers, it was found that the use of management tools is becoming more sophisticated as the level of education of the farmers increases. Dairy farmers took into account non-economic factors (values) at the moment of making a decision, such as: legacy, tradition (inheritance), enjoy working in rural areas, enjoy the dairy activity, independence etc. They considered, in addition, economic factors, such as: sale of animals, monthly payment and profitability. It seems the use of management tools had no direct influence on the decision of the dairy farmer to continue in the activity, since farmers who did not use any management tools showed interest in the continuity. Although those farmers that used management tools were the most eficiente.
49

Modelo de sistema de gestão da qualidade para propriedades rurais leiteiras.

Lima, Luciano Silva 02 December 2004 (has links)
Made available in DSpace on 2016-06-02T19:51:59Z (GMT). No. of bitstreams: 1 DissLSL.pdf: 1001454 bytes, checksum: 379f1a5f21d63f323df3f06bc884c6ab (MD5) Previous issue date: 2004-12-02 / Financiadora de Estudos e Projetos / The agents of Brazilian dairy production chain work with critical rates of losses, starting from the dairy rural company that, several times, supply raw material characterized by low quality. This low quality may be justified by problems with planning, execution and control of daily activities in the farm. In this context, the present dissertation proposes a reference model of Quality Management System (QMS) for dairy farms. The model´s aim is establish the quality management requirements and the principles needed to assure the quality and security of milk, as well as needed to the continuous improvement of the process activities. The model contents two modules: Basis Module is shaped by a set of principles and conditions that orient all the system, while Requirements Module is shaped by a set of requirements that execute and manage the system in the practice based on data and facts generating decisions and plans in the daily of dairy farm. Farther on showing the modules details, this work presents a proposal of the QMS documentation structure and also a set of suggestions to the model implementation in the dairy farms. With its implementation, the model may minimize costs with losses and reworks, and generate higher satisfaction to the farm´s customers (industrial establishments) and final consumers of chain. According to the assessment realized with a sample of the target public (farmers and rural extension agents), the model accomplishes its purpose. Although its language had been evaluated as a weakness, the QMS was considered an important mean to the Brazilian dairy farmers get a professional status. / Os agentes da cadeia produtiva leiteira brasileira convivem com índices críticos de perdas, começando pela propriedade rural que, muitas vezes, fornece matéria-prima de baixa qualidade. Baixa qualidade que pode ser justificada por problemas de planejamento, execução e controle das atividades do dia-a-dia da propriedade. Nesse contexto, a presente dissertação propõe um modelo de referência de Sistema de Gestão da Qualidade (SGQ) para propriedades rurais leiteiras. A finalidade do modelo é estabelecer os princípios e requisitos de gestão da qualidade necessários à garantia da qualidade e da segurança do leite, bem como à melhoria contínua das atividades inerentes ao processo de produção leiteira. O modelo é constituído por dois módulos: o Módulo Base do SGQ é formado por um conjunto de princípios e condições que norteiam todo o sistema, enquanto que o Módulo Requisitos do SGQ é formado por um conjunto de requisitos que executam e gerenciam o sistema na prática, com base em dados e fatos gerando decisões e planos no dia-a-dia da propriedade leiteira. Além do detalhamento dos módulos, apresenta-se uma proposta de estrutura de documentação do SGQ bem como um conjunto de recomendações para implantação do modelo em propriedades rurais leiteiras. Uma vez implantado, o modelo contribui para a redução de custos com perdas e retrabalhos, bem como para a geração de maior satisfação ao cliente (laticínios) e aos consumidores finais da cadeia. Segundo a avaliação realizada junto aos representantes de seu público-alvo (produtores e extensionistas rurais), o modelo teórico cumpre a finalidade para a qual foi proposto. Apesar de sua linguagem ter sido avaliada como um ponto fraco, o SGQ foi considerado um importante meio para a profissionalização do produtor rural brasileiro.
50

Identificação de fatores de risco para mastite subclínica em rebanhos do estado de Santa Catarina / Identification of risk factors of subclinical mastitis in herds in the Santa Catarina State

Cardozo, Leonardo Leite 15 July 2013 (has links)
Made available in DSpace on 2016-12-08T16:24:15Z (GMT). No. of bitstreams: 1 PGCA13MA111.pdf: 1564151 bytes, checksum: f070dcd7283938facf093efc2818ea37 (MD5) Previous issue date: 2013-07-15 / This study was aimed to identify risk factors of subclinical mastites in dairy herds located in the region of West, Midwest, Serrana and Southern in Santa Catarina State, Brazil. The experiment was conducted in 30 dairy herds, totaling approximately 1.700 lactating cows, participating in Dairy Control Service of Santa Catarina Association of Cattle Breeders (ACCB) during the period November 2011 to December 2012. Information on the characterization of milk-producing units and their management programs were obtained by survey with the farmes as well as by monitoring the farms. During the development of the work selected farms were visited three times to update the data, and after the visits has assembled a database with information from test dairy controls and survey. The dynamics of subclinical mastitis was determined from the ratio of the somatic cell count (SCC) of the previous month to the current month s SCC. In the analysis of the dynamic of intramammary infections was initially used the Chi-square (X²) to test associations between each independent variable with the dyna =mics of mastitis, followed by logistic regression analysis to estimate the risk of new infections in contrast to healthy cows and chronic infections compared to new infections. The average count of SCC was 493, 728 cells/mL, being that in 32.3% of control cows were healthy (SCC<200,000/mL). the explanatory variables that composed the final logistic regression model for risk of a cow developing a new case of mastitis in relation to healthy cows were parity, hyperkeratosis at the teat, udder depth, udder dirt and adoption of milking line. Cows with> 4 birth had 1.65 times the risk of new intramammary infection compared to ptimiparous cows (P <0.01). For cows with a mean score of hyperkeratosis ends above of 3 (scale of 1 to 4) was observed 1.61 times greater risk of developing new infections, cows with udders below the hock achieved risk of 2.46 (P <0.001) and cows with dirty udders many showed risk of 1.55 times of becoming infected. Farms hat do not perform line for milking animals had infected increased the 1.55 times greater risk of developing infections. The final model of logistic regression showed the best explanation for the risk of developing a chronic infection of subclinical mastitis in relation to new subclinical mastitis including maintenance of milking equipment, stage of lactation and udder depth. Farmsn that perform maintenance of milking equipment only eventual had 2.17 times greater risk of owning cows with chronic infection (P <0.001) cows above 100 days in milk already increased risk, ranging from from 2.70 to 5.88 and cows with udder depth at or below the hock shown risk approximately 1.65 compared to the cows shallowe udders (P <0.01) / O presente trabalho teve como objetivo identificar os fatores de risco para mastite subclínica em propriedades leiteiras localizadas nas mesorregiões Oeste, Meio-oeste, Serrana e Sul do Estado de Santa Catarina. O experimento foi desenvolvido em 30 rebanhos, perfazendo aproximadamente 1.700 vacas em lactação, participantes do Serviço de Controle Leiteiro da Associação Catarinense de Criadores de Bovinos (ACCB) durante o período de novembro de 2011 a dezembro de 2012. Informações sobre a caracterização das unidades produtoras de leite e seus programas de manejo foram obtidas a partir de questionário aplicado aos produtores, bem como através do acompanhamento das propriedades. Durante o desenvolvimento do trabalho as propriedades selecionadas foram visitadas três vezes para atualização dos dados, sendo após as visitas foi montada uma base de dados com informações do controle leiteiro e do questionário. A dinâmica da mastite subclínica foi determinada da relação da contagem de células somáticas (CCS) do mês anterior com a CCS do mês atual. Para análise da dinâmica das infecções intramamárias foi primeiramente utilizado o teste Qui-quadrado (2) para testar associações entre cada variável independente, seguida de análise de regressão logística para a estimativa de risco de novas infecções em contraste às vacas sadias e infecções crônicas em comparação às novas infecções. A contagem média da CCS foi de 493.728 células/mL, sendo que em 43,3% dos controles as vacas encontravam-se sadias (CCS <200.000/mL). As variáveis explicativas que compuseram o modelo final de regressão logística para risco de uma vaca desenvolver um novo caso de mastite em relação às vacas sadias foram à ordem de parto, hiperqueratose da 8 extremidade dos tetos, profundidade do úbere, sujidade do úbere e adoção de linha de ordenha. Vacas com > 4 partos apresentaram risco de 1,65 vezes de nova infecção intramamária em relação às vacas primíparas (P <0,01). Para vacas com escore médio de hiperqueratose acima de 3 (escala de 1 a 4) foi observado risco 1,61 vezes maior de contrair novas infecções, vacas com úberes abaixo da linha do jarrete obtiveram risco de 2,46 (P <0,001) e vacas com úberes muitos sujos apresentaram taxa de risco de 1,55 vezes maior de tornar-se infectadas. Propriedades que não realizam linha de ordenha para animais mais infectado apresentaram taxa de risco de 1,55 vezes mais de contraírem infecção. O modelo final de regressão logística que apresentou melhor explicação para o risco de desenvolver uma infecção de mastite subclínica crônica em relação a novos casos de mastite subclínica incluiu as características manutenção dos equipamentos de ordenha, estágio de lactação e profundidade do úbere. Propriedades que realizam a manutenção dos equipamentos de ordenha de forma apenas eventual apresentaram taxa de risco 2,17 vezes maior de possuir vacas com infecção crônica (P <0,001), vacas a partir de 100 dias de lactação já apresentam um risco aumentado, variando de 2,70 a 5,88 e vacas com profundidade do úbere junto ou abaixo da linha do jarrete mostraram risco de aproximadamente 1,65 em comparação com as vacas com úbere mais raso (P <0,01)

Page generated in 0.0676 seconds