School of Agriculture, Food and Ecosystem Sciences - Theses
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ItemGrazing ecology and high producing dairy cows( 2005)This body of work (82 papers in scientific journals and 2 books) encompasses two broad areas of work. They are 1) growth, nutritive value and management of pastures grazed by dairy cows (40 publications), and 2) supplements for grazing dairy cows, with a particular focus on responses associated with supplement use and digestion in the rumen (44 publications). These two areas of research are inextricably linked and, taken together, have been termed `Grazing Ecology'. Of the 84 publications included, the candidate was the senior or sole author of 67% of them. The chronological development of the work reported includes research on stocking rates reported in the early 1980's through to the development of Diet Check, a decision support tool incorporating much of the information generated during the previous two decades, in the early 2000's. The publications cover aspects of grazing management to optimise growth, persistence and nutritive value of irrigated annual and perennial pastures for dairy cows. Most of this research has incorporated some aspect of stocking rate, whether it be stocking rate per se in long term experiments or frequency and/or intensity of defoliation in shorter term experiments. The aim was to establish optimum grazing strategies that best effected the compromise of maximum intake of pasture of high nutritive value while satisfying the requirements for maintenance of pasture growth and persistence of a balance of desirable pasture species. The research allowed the definition of the intake and nutritive characteristics of pasture grazed by lactating dairy cows under a range of management conditions. At the same time, strategies to effectively feed supplements were investigated. When more than one feed is offered to dairy cows, associative effects play an important role in the eventual responses achieved. Balance of nutrients, particularly in the rumen, and substitution of supplement for pasture in the diet of grazing dairy cows, were the main aspects of the associative effect between feeds considered in the research reported here. Substitution can have a huge effect on the responses obtained from supplements, and the type of supplement, by influencing the balance of nutrients ingested into the rumen, affects the composition of the milk produced. Finally, some attempt has been made to draw much of the information on pasture management and supplementation of grazing dairy cows together for use by dairy farmers and their advisers, and to define gaps in knowledge. This has been done by reviewing the scientific literature, and by the use of modelling to provide simple tools for tactical decision making. Although the research was undertaken in northern Victoria, many of the results apply equally in other areas of the world where pasture constitutes a major proportion of the diet of dairy cows. Victoria currently produces more than 60% of Australia's milk, with northern Victoria producing more than 40% of that. The development of dairying in Victoria mirrors much of the progress of the research reported in this collection of scientific publications. Before 1982, dairy farming was almost totally based on grazed pastures and the use of pasture supplements (hay and silage). A severe drought occurred in 1982, which prompted a serious consideration of the use of supplements for lactating cows grazing pasture. Today, dairy systems in Victoria vary to a huge extent, with the energy provided by pasture ranging from 0 to 100%. Over this period, average milk production has increased, from about 3000L/cow per lactation to more than 5000L/cow. With a fine line separating profit and loss in dairy businesses that basically depend on the price received for manufactured products on overseas markets, both grazed pasture and supplements need to be used optimally. The challenge has been to provide information and tools to allow dairy farmers to achieve this objective. I believe that my research, particularly in relation to pasture intake, substitution and associative effects, has been instrumental in allowing pasture-based dairy farmers to continue to remain viable in Australia, and that many of the principles developed apply wherever pasture constitutes a significant proportion of a cow's diet.
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ItemA process for practice : learning for change in the dairy industry( 2002)The dairy industry in Victoria, and indeed agriculture more generally, is facing a new generation of increasingly complex issues. Problems associated with issues such as the deregulation of markets and sustainable farming practices are ones which seemingly can not be addressed through the application of technology alone. In 1999 a review of human resource development and extension (HRD&E) in Australia's dairy industry identified that for farmers to be adequately supported in tackling such issues, the HRD&E system required extensive development, particularly in the area of understanding farmer learning. Learning plans were discussed as a possible means by which this could be achieved, however there was much ambiguity associated with this term, particularly for extension practitioners. Thus this project was born and aimed to explore the learning, motivation and change behaviour of dairy farmers in south west Victoria in relation to improving grazing management performance. After a review of the potential paradigms through which this research could be explored, practice theory and the interplay model were found to be the most appropriate, as such an approach enabled the researcher to engage farmers at the level of on farm practice. The underlying epistemological paradigm through which the area of learning plans was explored combined the constructivist and critical theory positions, while the methodologies applied were a collective case study approach, using a Straussian style of grounded theory. Through the interplay model it became clear that for this research to be effective, an improved understanding of farmer learning needed to be examined in terms of the provision of extension services. As such, new theory generated was explored and applied in practice using an action research approach, engaging five extension practitioners from around the state of Victoria. Overall, this research has produced a new model which describes farmer learning as a process of change where action and intention are informed, challenged and balanced by potentially opposing worldviews. The action research phase of the project identified that such learning would be best facilitated through partnerships with extension. Such partnerships involve the practice of extension working towards better understanding the farmers needs as well as the nature of their farming system, and then using this understanding to inform the application of extension resources. The process through which this concept was generated is clearly outlined and discussed, as are the implications that this research presents for the future development of extension in Victoria.
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ItemThe economics of irrigated dairyfarming in the Central Gippsland irrigation district( 1964)It is the purpose of this thesis to investigate the level of managerial efficiency obtaining on a group of dairy farms situated in the Nambrok-Denison area of the Central Gippsland Irrigation District, and to enquire into the possible avenues of increasing the profitability of such undertakings under existing conditions. Emphasis is restricted to analysis at the individual farm level, although the results could be adapted to shed some light on a number of important questions of national policy. Farm management is concerned with the proper combination and operation of production factors, and the choice of crop and livestock enterprises to bring about a maximum and continuous return to the most elementary operation units of farming (Yang 1958, p.4). A broader definition encompasses two further functions, viz. acquisition of factors of production, and adaptation of the farm plan to changing conditions (Castle and Becker 1962, p.253). The present investigation is restricted to an examination of the existing resource allocation efficiency. Thus it represents only a partial analysis of the farm management problem, but one which focuses attention on the more feasible possibilities of increasing farming efficiency in the short run; namely a more efficient reallocation of the resources presently employed on the farm, and the more profitable avenues of investment of additional funds. Farm management research employs the two major processes common to scientific research in general - deduction and induction (Heady 1952., p.14) - and the following pages illustrate this procedure. First, the problem is explicitely stated - how efficiently are the individual farms being managed given relevant restrictions? Second, the theoretically optimum model is defined - in terms of the criteria for efficient resource allocation - and the empirical procedures to be employed in investigating departure from this optimum, lug. residual imputation and regression techniques, are described. The required empirical data is then collected and analysed using the statistical procedures appropriate to the above techniques. Finally, the results of the empirical investigation are examined in the light of the defined criteria for efficient resource use, and on the basis of this comparison between actual and theoretically optimum conditions, suggestions are made regarding the possibilities of more closely approximating the latter.
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ItemQuality of goat milk produced in Victoria( 1990)Preparation of quality standards for the developing goat milk industry in Victoria required study of unknown current quality levels of chemical, physical and microbiological parameters. Milk delivered weekly or twice weekly to goat cheese manufacturers from 11 farms was sampled over 8 months. Samples were examined for composition, freezing point, extraneous matter, standard plate count, coliforms and inhibitory substances, using Australian Standards Methods. Mean values and (range) for fat, true protein, and lactose were 4.45 percent(2.96 to 5.88); 3.20 percent (2.70 to 4.61); and 4.60 percent' (3.92 to 5.17). Respectively average (range) total solids and ash content were 12.9 percent (11.9 to 15.8); and 1.02 percent (0.69 to 1.53). Freezing points (C) were lower than for cows' milk, viz: - 0.541C (-0.541 to -0.519 C ). Seventy percent of samples had low levels of extraneous matter. Standard Plate Count ranged from 500 cfu/ml to >106/m1 with only 26 percent of samples complying with the standard for cows' milk (5 x 104 cfu/ml). Seventy percent of samples contained coliforms >100 MPN/ml and 30% contained inhibitory substances at levels >0.002 microgram/mI. Setting microbiological standards is premature due to poor over-all quality and an advisory system coupled with quality monitoring is preferred. Standards for other parameters could be set.