8,992 research outputs found

    The epidemiology of mastitis in Australian dairy cattle : a dissertation submitted in partial fulfilment of the requirements for the degree of Masters of Veterinary Studies (Epidemiology)

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    This study represents an aggregation of knowledge on mastitis within the Australian dairy industry. Aspects of the epidemiology and economics of mastitis have been collated and areas of missing knowledge identified. A clinical treatment trial was conducted on subclinical mastitis to identify the role of therapy upon subclinical infection. The effect of individual variables on mastitis risk was studied and aggregated in order to facilitate the development of a computer simulation model of mastitis within Australian dairy herds. A literature review of mastitis within the Australian dairy industry was conducted. The economic impact of mastitis was examined and the pathway of economic loss to the dairy industry is discussed. The epidemiology of mastitis was studied with special emphasis on quantification of the effect of individual risk factors on the occurrence of disease. Performance parameters for the current diagnostic tests applied within the dairy industry are presented and their suitability for use in a commercial environment discussed. The impact of self-cure and the efficacy of therapeutic intervention in the disease are examined. The role of culling is presented. The chapter concludes with an estimation of die total economic losses experienced on a commercial dairy farm in Victoria in 1998 for three different mastitis levels. The economic benefit to be gained from a reduction in mastitis is also presented. A clinical treatment trial of subclinically infected cows (high somatic cell count) was conducted in order to determine if therapeutic intervention was an effective management tool. Cows with somatic cell counts in excess of 500,000 cells per ml and more than 14 days calved were selected and randomly assigned to treatment and control groups. A pooled quarter milk sample was taken prior to treatment and repeated at around six weeks after treatment. Treated cows received a course of intramammary and parenteral antibiotics and control cows were untreated. Cows were followed for the rest of the lactation of treatment and into the subsequent lactation and somatic cell counts were recorded. The major pathogens identified were S anreus and S uberis. Treatment did not have a significant or commercially useful effect upon bacteriological cure rates, survival of cows to the next lactation or somatic cell count for the remainder of the lactation. Treatment of high somatic cell count cows during lactation is not recommended and is discussed. A requirement exists for the development of a stochastic simulation model of mastitis within Australian dairy herds. The structure of such a model was developed and is presented. Underlying production and somatic cell count responses in Australian cattle were derived. Infection status variables were included and stochasticity was introduced through the use of control variates. State transition probabilities were collected from the literature. Deficiencies in knowledge were identified and methods for modeling these deficient areas discussed. The aggregated information is presented. It is expected that a working stochastic simulation model of mastitis within Australian dairy herds will be developed from infomation collected in this dissertation

    Stochastic utility-efficient programming of organic dairy farms

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    Opportunities to make sequential decisions and adjust activities as a season progresses and more information becomes available characterise the farm management process. In this paper, we present a discrete stochastic two-stage utility efficient programming model of organic dairy farms, which includes risk aversion in the decision maker’s objective function as well as both embedded risk (stochastic programming with recourse) and non-embedded risk (stochastic programming without recourse). Historical farm accountancy data and subjective judgements were combined to assess the nature of the uncertainty that affects the possible consequences of the decisions. The programming model was used within a stochastic dominance framework to examine optimal strategies in organic dairy systems in Norway

    Organic dairy farming in Norway under the 100% organically produced feed requirement

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    The EU regulation governing organic production will require 100% organic feed in organic dairy systems from August 2005 compared with 85% currently in Norway. This study aimed to assess adjustments in resource use and financial impacts on organic dairy herds using a discrete stochastic programming model. Farm management effects of the regulatory change varied between farm types. For the two organic dairy systems examined, both having a milk quota of 100 000 litres but with varying farmland availability, the introduction of the 100% organic feed regulation resulted in an economic loss of approximately 6-8% of the net income compared to the current regime. The economic loss was mainly due to the considerable higher price of organic compared to conventional concentrates

    Adding value to cull cow beef

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    End of project reportThis project addressed the prospects of increasing the value of cull cow beef and examined the potential of a number of different management and dietary strategies. In Ireland, the national cow herd contributes 350,000 animals to total beef production annually, which represents 22% of all cattle slaughtered (DAF, 2007). A dominant feature of beef production in Ireland is the disposal of cows from the dairy and beef industries, the time of year at which culling occurs influences the number of cows available for slaughter. Suitability of a cow for slaughter is generally not a consideration for dairy or beef farmers

    Modelling the dynamics of intramammary E. coli infections in dairy cows: understanding mechanisms that distinguish transient from persistent infections

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    The majority of intramammary infections with Escherichia coli in dairy cows result in transient infections with duration of about 10 days or less, although more persistent infections (2 months or longer) have been identified. We apply a mathematical model to explore the role of an intracellular mammary epithelial cell reservoir in the dynamics of infection. We included biological knowledge of the bovine immune response and known characteristics of the bacterial population in both transient and persistent infections. The results indicate that varying the survival duration of the intracellular reservoir reproduces the data for both transient and persistent infections. Survival in an intracellular reservoir is the most likely mechanism that ensures persistence of E. coli infections in mammary glands. Knowledge of the pathogenesis of persistent infections is essential to develop preventive and treatment programmes for these important infections in dairy cows

    Mathematical Models in Farm Planning: A Survey

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    Using accelerometer, high sample rate GPS and magnetometer data to develop a cattle movement and behaviour model

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    The study described in this paper developed a model of animal movement, which explicitly recognised each individual as the central unit of measure. The model was developed by learning from a real dataset that measured and calculated, for individual cows in a herd, their linear and angular positions and directional and angular speeds. Two learning algorithms were implemented: a Hidden Markov model (HMM) and a long-term prediction algorithm. It is shown that a HMM can be used to describe the animal's movement and state transition behaviour within several “stay” areas where cows remained for long periods. Model parameters were estimated for hidden behaviour states such as relocating, foraging and bedding. For cows’ movement between the “stay” areas a long-term prediction algorithm was implemented. By combining these two algorithms it was possible to develop a successful model, which achieved similar results to the animal behaviour data collected. This modelling methodology could easily be applied to interactions of other animal specie

    Structural change in the dairy sectors of Germany and the Netherlands - A markov analysis

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    With the milk quota announced to be abolished in the future, the dairy sector is going to face a significant policy regime shift. This paper sets out to analyze the impact of milk quotas on the dairy farm structure of two important milk producing member states: Germany and the Netherlands. Based on proper behavioral assumptions, non stationary Markov chain models are specified and estimated using a generalized cross entropy procedure, which takes into account both sample and prior information. Moreover four mobility indicators characterizing structural change are developed and calculated. Structural change in the dairy sector as measured by the mobility measures is faster in West Germany than in the Netherlands. However, in the transition region East Germany structural change outpaces that of the traditional German and Dutch dairy sectors by a factor two or more. The introduction of milk quotas as of April 1, 1984 reduced overall farm mobility for the Netherlands, but increased mobility in West Germany. However, in both cases the milk quotas lead to an increase in upward mobility

    Technical Efficiency of Smallholder Dairy Farmers in the Central Ethiopian Highlands

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    Despite having the second largest livestock population in Africa and favorable climate, the contribution of the livestock, especially the dairy sector to the Ethiopian economy is minimal. The per capita consumption of dairy products of 16 liters is one of the lowest in the world. With increasing income and urbanization, the demand for dairy products is expected to increase. A number of studies have examined the potential of the dairy sector to satisfy existing as well as future demand for dairy products. Most of the studies, however, focus on technological constraints such as poor genotype of indigenous animals, tropical animal diseases, availability of feed and other related services and recommend costly technological solutions aimed to alleviate those constraints. Yet there is evidence of inefficiency and significant post harvest losses of milk. We used a Cobb- Douglas stochastic production function to analyze the inefficiencies of a random sample of 74 smallholder dairy farmers in the Central Ethiopian Highlands. Results show that forage and concentrate feed, number of cross breed cows and expenditures on veterinary services are significant determinants of milk output. We also found evidence of systematic inefficiency in dairy production associated with farmers' educational level and livestock training that explains almost 90% of the variation in milk production. The average efficiency score of farmers in the sample is 79%. Thus milk output can be increased on average by 21% with existing technology by training farmers in modern management practices in feeding, calving, milking, storing, processing and marketing.Smallholder dairy, technical efficiency, stochastic production function, Ethiopia, Livestock Production/Industries, Productivity Analysis,
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