School of Agriculture, Food and Ecosystem Sciences - Theses
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ItemThe effect on some milking characteristics of cows of changing the flow rate thresholds of automatic cluster removers in a seasonally calving dairy herd( 2004)An experiment to investigate the effects of altering the end-of-milking point values of automatic cluster removers (ACRs) from 0.40 kg/min (Control) to 0.70 kg/min (Fixed ACR), or 1.00 kg/min (Rising ACR) over an extended period from the peak until the end of lactation of a seasonally calving pasture based herd has been conducted at the Victorian Department of Primary Industries Ellinbank research dairy. One hundred and ninety two cows. and heifers were used in the experiment (64 animals statistically allocated to each treatment group). A comparative analysis of results for each treatment group is presented for average milk yield, average milking duration, average maximum milking duration, average milk flow rate, average peak milk flow rate and udder health. The Fixed ACR treatment reduced the average daily milking duration by up to 7.6%, but only for a small portion of the treatment period. The Rising ACR treatment reduced the average daily milking duration significantly by up to 15.3%, for the majority of the treatment period. The Fixed ACR treatment did not reduce the average daily maximum milking duration whilst the Rising ACR treatment reduced the average daily maximum milking duration significantly by up to 17.9%, for the more than half of the treatment period. A marginal increase in average milk flow rate was observed for the Rising ACR treatment. Even though the Rising ACR treatment began the experiment with higher average peak flow rate for AM and PM it declined less than the Fixed. ACR or Control treatment throughout lactation, providing a mechanism for the, removal of the same amount of milk in a reduced time when compared with the other treatments. However the difference observed in peak flow rates was not statistically significant. No difference was found amongst the treatment groups when analysed for new cases of sub-clinical or clinical mastitis. The geometric mean of individual cow cell counts was significantly reduced for the Rising ACR treatment in the latter stages of lactation. Flow rate curves have been constructed from real milking data and are presented as examples of the large variation of actual- flow rate from a cows udder. The flow rates curves are used to track individual cows through lactation to observe changes in the cow's milking characteristics. Theoretical consideration is given to how particular types, or brands, of ACR operate under various conditions and it is shown that the results from this experiment could be replicated by using other types of ACR if they are managed correctly. This study has shown that significant labour productivity. benefits could be achieved by, increasing the ACR end-of-milking point settings to 1.00 kg/min without impacting milk yield. However, further work is suggested to ensure that udder health is not compromised. This is to certify that the thesis comprises only my original work except here indicated in the preface; due acknowledgement has been made in the text to all other material used; the thesis is 19400 words in length, inclusive of footnotes, but exclusive of tables, maps, appendices and bibliography.
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ItemForest management certification in West New Britain province, Papua New Guinea( 2004)The main objective of this study was to investigate the experiences of the stakeholders who participated or were affected by the `PNG Eco-forestry Program' forest certification scheme. The move to certification as a sustainable forest management alternative was introduced because from 1992 to 1995 the West New Britain Province and Papua New Guinea were under a lot of pressure from unsustainable conventional commercial logging, mainly controlled by large overseas based timber-mafia logging companies. The `PNG Eco-forestry Program' forest certification scheme was established and funded by the European Union under its STABEX FUNDS in 1995 as the Islands Regional and Community Development Program. The Program has achieved some significant outcomes in securing five project areas certified, covering an area of about 8,360 ha, and two newly established Eco-forestry projects one of which are in their final preparation stage for certification. However, to achieve sustainable forest management through certification, the Program is faced with the need for an eco-forestry policy. The application of the `Eleven Steps' approach to achieve sustainable forest management through certification is limited and faced considerable difficulties for seven main reasons: 1) the issue of not being recognized nationally as a management approach to achieve sustainable forest management; 2) the lack of proper research and awareness on current forest policy; 3) the lack of consideration for both markets for sawn timber and non-timber forest products; 4) the use of outdated forest inventory maps and equipment; 5) the lack of funding; 6) the premature relocation of the Program's head office from Kimbe to Lae, and 7) the lack of improvement in market price for sawn timbers. The results from this study suggested that the process of achieving sustainable forest management through certification was flawed for seven main reasons: 1) there were no ecoforestry policies; 2) there were no appropriate forest management standards; 3) the devaluation of the Kina caused a decline in real (free of inflation) market prices for sawn timber; 4) the lack of markets for non-commercial timber species and non-timber forest products; 5) the lack of funding; 6) the lack of participation by resource owners, and 7) the poor landownership determination processes. In addition, the under-resourced Provincial Forest Management Unit was reluctant to provide resource owners with technical and legal advice on current forestry and policy issues. This also negatively impacted the community's participation in the negotiation processes about their forest resources. The Government should change its approach to forest policies to favor of small-scale forestry operations, and improve the current market prices for sawn timber. The local forest owners will then be better able to move towards sustainability by implementing management standards based on ecological sustainability, using an improved system of certification based on the Eleven Steps process and the findings of this study. Recommendations on policy development and research have been provided.
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ItemSpring water use in raised bed cropping( 2004)Cultivation of heavy clay soils with the application of gypsum is often used to improve root exploration of the soil profile and hence more efficient use of the soil resource to enable higher grain yields of cereal crops. Soils in south-western Victoria are derived from tertiary basalts with high clay content and often dispersive subsoil. Cereal crops grown on these soils are prone to waterlogging. Waterlogging has been overcome with the use of raised beds. The hypothesis was that the heavy subsoil restricted rooting depth and hence efficient water extraction from the soil profile, particularly in the grain filling period during spring. Deep cultivation of the soil was proposed to overcome subsoil limitations. This study has compared the use of deep ripping, with and without the use of gypsum, to the use of direct drill techniques. Soil water use and plant root density have been compared for the different cultivation treatments. Soil water use indicated that the use of direct drill, compared with deep ripping, was favoured during years with dry autumn or delayed autumn breaks. Surface soil water was conserved in the direct drill treatments. The use of deep ripping, with and without the use of gypsum did not significantly increase the rooting density to a greater depth than direct drill. Furthermore the deeper roots failed to access soil water to improve grain yield compared with direct drill treatments. An increase in grain yield, with the use of deep ripping, was recorded in a year of above average rainfall in the growing season. The addition of gypsum, when deep ripping, provided no additional benefit to grain yield in the above average rainfall year.
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ItemManagement and yield of chilli (Capsicum annuum L.) : a case study from Punakha District, Bhutan( 2004)The objective of this study was to produce an accurate estimate of the yields of green chilli (Capsicum annuum L.) grown under village management condition in Punakha district, western Bhutan. The study also considered important agronomic factors of productions such as types and usage of fertilizers, chilli varieties, planting density, spacing, methods of sowing and transplanting. A total of 50 farming households from two Gewogs (sub-districts) of Talo and Guma were selected in Punakha. Of these, 24 households cultivated chilli using farmyard manure (FYM) and 26 used FYM and inorganic fertilizers (FYM+I). Farmers were interviewed about their farming practices. Yields were recorded on a weekly basis for six weeks within demarcated plots of 5x5 meters in farmers' fields. Soil samples from the sites were collected and analysed for soil nutrient status. Results indicated a very large variation in the yields of fresh green chilli. The average yield was estimated to be 23 t/ha, with the highest yield 37.6 t/ha and lowest 13.6 t/ha. Fertilizer applications also showed wide variations in rates and types. No significant correlations could be established between yield and any factor of production, including fertilizer use and type. The weak relationships seem to derive from a number of issues including farmers' individual methods of cultivating chilli, differences in level of inputs, limited resources and labour shortage. The soil fertility status was found to be relatively low, although there was an abundance of some elements of soil nutrients in the FYM cultivated sites. It is suggested that research centres in the region should conduct more on-station research trials, to establish science-based extension advice for chilli farmers and narrow the variation in the yields of chilli. This will improve the predictability of chilli yields, which is of great interest to farmers. It should be possible to increase the current average yield from 23 t/ha to 30-35 t/ha, develop and recommend the optimum use of fertilizers for chilli production, preserve the local chilli provenance through breeding programs and develop simple, tested agronomic practices which suit farming system which have limited access to human labour.
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ItemAn investigation of environmental conditions experienced during the life of high value wood components and products( 2004)The purpose of this project was to collate data on Australian wood products' exports as well as the environmental conditions that these products are exposed to during manufacture, transportation and service. These data are essential for understanding the potential for wood components to `move' in response to periods of drier or more humid conditions than those at the time of manufacture. The knowledge generated will contribute to a subsequent project, whereby a user-friendly tool will be developed to enable for the design and production of appropriate components, joints, adhesives, coatings, and packaging systems that will ensure superior performance of Australian wood products throughout a wide range of climatic conditions. Wood, a hygroscopic material, will undergo changing moisture contents, fluctuating with changes in atmospheric conditions. As a consequence of these changes in moisture content, wood will swell or shrink. For high-value products, these changes can be detrimental to the utility of the product, for example panels can warp, drawers and doors can jam, and glued components can delaminate. Despite the common occurrence of product degrade or failure due to exposure to changing atmospheric conditions, very little effort has been undertaken to quantify the range of expected conditions for Australian exports. Australian forest industries have a long history of export trade in a wide range of products, from woodchips and sandalwood, through to high-value manufactured commodities such as outdoor furniture and assorted flooring products. Current export markets for high-value wood products were found to be predominantly northern hemisphere countries, including United States of America, China (including Hong Kong), Korea, Japan, Europe (including the United Kingdom) and the Middle East. Other regions importing Australian high-value wood products were south-east Asia (Philippines, Indonesia, Thailand and Malaysia), New Zealand and South Africa. A survey was undertaken to determine the range of value-added products currently exported, and it was found that high volumes of flooring, decking, outdoor furniture and kiln-dried boards for furniture and pre-finished flooring products account for the majority of our value-added export effort. There are currently only minor volumes of assembled indoor furniture suites exported from Australia. Wood fibre panels such as plywood, particleboard and medium density fibreboard were outside the scope of this project due to the in-built stability of these products and only solid wood products were considered. Data generated from the survey included the range of timber species used in the manufacture of export products, sawn orientation and typical section sizes used in components. Results from this work showed that the major timbers are: the ash-type eucalypts from south-eastern Australia; jarrah from Western Australia; spotted gum, hoop pine, white cypress, imported kwila, blackbutt, brush box and Sydney blue gum from New South Wales and Queensland. Environmental conditions, especially the combined effect of temperature and relative humidity in microclimates as determined during this research project, can fluctuate extensively during transport from one location to the next. Equilibrium moisture contents (EMC) as low as 5% and as high as 20% were experienced during the shipping of wood products. In addition, the conditions at the place of manufacture (often 10 to 12% EMC) may be vastly different to the environment where the wood products are ultimately placed in service. The in-service conditions for many of our export destinations are between 6 to 9% EMC. This range of conditions, from manufacturing through transportation and in-service, can potentially create problems, due to wood components swelling and/or shrinking corresponding with periods of higher and/or lower temperatures and humidities. Packaging systems incorporating plastic and cardboard were shown to offer some protection against humidity changes. For the Australian wood-manufacturing sector to achieve and maintain a reputation for superior high-performance products in overseas markets, designers and manufacturers will require a clear understanding of the potential effects of changing environmental conditions on their products. When the range of conditions anticipated throughout the service life of an item is combined with data for timber stability, a manufacturer can allow for movement in the design of the item. An understanding of effective packaging systems is also necessary to ensure maintenance of timber moisture content during transportation. The research highlighted the inherent risks of exporting high-value wood products to distant markets and the need for development of a user-friendly tool, which would allow manufacturers to determine appropriate design parameters such as species, dimensions, jointing systems, adhesives, coatings and packaging for export products.
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ItemAssessment of the cicer gene pool : molecular variability and ascochyta rabiei resistance screening( 2004)A comprehensive understanding of the genetic variation available within Cicer collections is important for the efficient selection of parents, for introgression of genetic material into superior cultivated lines and for the implementation of effective genetic conservation programs. Wild Cicer relatives may offer alternate genetic sources that may be incorporated into the cultivated chickpea. The aim of this thesis was to investigate the genetic relationships and diversity that exist within the unique Cicer germplasm collection and evaluate it for novel sources of resistance to Ascochyta rabiei. Amplified Fragment Length Polymorphism (AFLP) analysis was used to evaluate the genetic variation among cultivated chickpea and wild Cicer relatives. In total, 214 marker loci were assessed, of which 211 were polymorphic across the 95 accessions that represented 17 species of Cicer. The highest instraspecific variation was detected in C. pinnatifidum and the lowest was in C. macracanthum. Three main species groups were identified by UPGMA clustering using Nei's pair-wise distance calculations. Group 1 included the cultivated species within which C. reticulatum accessions were clustered closest to the C. arietinum cultivars Lasseter, Kaniva and Bumper, supporting the hypothesis that C. reticulatum is the most probable progenitor of the cultivated species. Cicer bijugum, C. judaicum and C. pinnatifidum were clustered together creating Group 2. Group 3 contained all nine perennial species assessed and two annual species C. yamashitae and C. cuneatum. The genetic distance detected between Group 1 and Group 3 (0.13) was equivalent to the genetic distance detected between Group 1 and Group 2 (the primary and annual tertiary species respectively; 0.14). This indicated that the perennial tertiary species may be as valuable for increasing variation to incorporate novel germplasm in the cultigen as the annual tertiary species. Chickpea world germplasm collections were reported to contain a low frequency of ascochyta blight resistance and a narrow genetic basis that could limit the progress of chickpea breeding program. In an effort to screen for novel sources of resistance to ascochyta blight, fifty-six accessions of eight annual wild Cicer species were evaluated under a controlled environment that was optimal for A. rabiei growth. Seven out of the 56 accessions tested (including susceptible control accessions) were classified resistant or tolerant to ascochyta blight at 21 days after inoculation. Among the wild species, C. judaicum was the most resistant species with four accessions showing resistance, whereas C. reticulatum was the most susceptible with no resistant accession rated.
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ItemThe economic evaluation of forage research results( 2004)Three economic analyses were conducted on the results of dairy forage production experiments undertaken in Victoria. The first analysis investigated the level of pasture production increases that would have to be achieved to warrant the investment in different soil modification options. This analysis took pasture production data and using a computer program "UDDER" (Larcombe 1990) generated farm data which was then applied to development budgets. The increase in pasture growth rate required was such that it is unlikely that investment in the soil modification systems tested here will produce a satisfactory return on investment. The second analysis investigated the use of different pasture species combinations on a dairy farm in northern Victoria. A linear programming model was developed that balanced the energy requirements of the milking herd with the energy supplied from pasture and supplements. The results showed that the most profitable mix of pasture depended on the energy supply profile of the pasture and the requirements of the herd. The proportion of autumn and spring calving cows in the herd in part determined the most profitable pasture mix. The effect of grazing management on profit was the subject of the third study. A farm model was constructed that balanced the energy, protein and neutral detergent fibre requirements of the milking herd with that supplied by pasture and supplements and optimised operating profit. The results of a grazing trial conducted in south-west Victoria were entered into the model and the operating profits for each treatment compared. The results suggested that while Operating profit was related to total pasture consumption, the timing of the pasture consumption impacted on operating profit. The results also suggested that grazing frequency may have affected operating profit more than grazing intensity.