School of Agriculture, Food and Ecosystem Sciences - Theses
Permanent URI for this collection
Search Results
1 - 3 of 3
-
ItemThe economic viability of automatic milking systems in Australia's pasture-based dairy farm systems: a case study analysis( 2016)Fluctuations in prices, costs and seasonal conditions, and increasing competition will continue to place pressure on profit margins for operators of all dairy systems. Good management and decision making skills is fundamental to ensuring that introducing new technologies, such as automatic milking systems (Mcwilliams et al.), are integrated into the whole farm system to make the best use of a given set of resources and circumstances, and realise the wide array of benefits technology has to offer some people in dairy. Increasing intensity of dairy farms and rising labour costs have helped to induce wider adoption of AMS technology in Europe and other countries. Similarly, the characteristics that have led to the wide adoption of AMS technology are increasingly evident in Australia’s dairy industry. Adapting the AMS technology to Australia’s pasture-based dairy systems has in the recent past been considered a complex challenge and requiring careful implementation as information remains limited on a national and global level. However, in recent years, the knowledge around the adoption of AMS in Australia’s pasture-based dairy systems has increased markedly with the ‘practical operated experience’ of AMS farms being fine-tuned and operating competitively. The key research question to be investigated in this thesis is if AMS technology adopted in Australia’s pasture based systems with voluntary cow traffic is competitive, in terms of profit, returns to capital, risk and non-pecuniary net benefits, when compared to Australian dairy farmers using conventional milking systems. This proposition will be tested by assessing the biophysical and economic performance of two dairy farm case studies, a Gippsland farm using ‘single box AMS’ and a Tasmanian farm using the ‘automatic milking rotary’. These two dairy farm case studies were chosen because they are deemed to have successfully integrated AMS into their whole farm system and are realising the benefits that are available from AMS. The case studies represent the use of the AMS technology at a steady state. For each case study, its biophysical and economic performance for an individual year was compared with the performance of other farmers in the region using conventional milking systems in the same year, where possible, and also over a hypothetical run of years with ranges of prices and seasonal conditions. Risk and uncertainty is also investigated in detail by running scenarios that represent long term typical prices, costs and rainfall. The major finding of this investigation is that the two AMS farms studied in Gippsland and Tasmania are capable, under the current management, of operating competitively under the seasonal and economic conditions that have occurred in the past and are likely to occur in the future, when compared to farms using conventional milking systems in the same region and under the same conditions. Ultimately, the success of incorporating AMS into Australia’s pasture-based dairy systems will depend almost completely on the human element. Good managers can make almost any system work well and profitability.
-
ItemNon-phage inhibition of cheese starter lactococci( 2002)Modern, large scale Cheddar cheese manufacture is dependent on reliable acid production by Lactococcus lactis subspecies cremoris and subspecies lactis starter cultures. Any inhibition of acid production may affect cheese quality, disrupt production schedules and reduce profitability. The presence of antibiotic residues in manufacturing milk resulting from the treatment of mastitis in lactating cattle is a potential source of starter culture inhibition. Therefore, a range of antibiotic concentrations was assessed for measurable inhibitory effects on acid production and compared to the minimum detectable concentrations by approved screening test procedures. Antibiotics were selected from formulations approved for use on lactating cattle for the treatment of mastitis. Novobiocin, lincomycin, oleandomycin and oxytetracyline HCl, all non-β-lactam antibiotics, inhibited acid production of one or more L. lactis strains at antibiotic concentrations below the detectable limit of standard screening procedures. Depending on the antibiotic, either or both the Bacillus stearothermophilus (var. calidolactis) disk assay and/or the Delvo SP assay were ineffective at detecting the antibiotics at concentrations required to inhibit the starter strains. Consequently, antibiotic residues below the detectable limits of these testing procedures could cause significant starter culture inhibition, disrupting cheese making schedules. Another potential source of starter culture inhibition is related to raw milk quality and the practice of refrigerated storage prior to processing. Previous studies differed as to whether the growth of psychrotrophic organisms would have a detrimental impact on subsequent acid production by starter bacteria employed in cheese manufacture. In this study, no inhibition of acid production by a commercial L. lactis subsp. cremoris strain was evident when grown in milk that had undergone short term temperature abuse. Antimicrobial systems native to bovine milk may also have an adverse impact on starter culture performance. The present study assessed the inhibitory effect of an activated lactoperoxidase system (LPS) on a range of L. lactis cultures. All of the strains were significantly inhibited when grown on reconstituted skim milk in the presence of an active LPS. Inhibition of acid production by strains grown on glucose was also observed, leading to further investigations to describe the inhibitory process. A non-phosphoenolpyruvate phosphotransferase (PEP/PTS) dependent glucose transport system, first observed in 1980 in one L. lactis subsp. lactis strain, was hypothesised as a link in strain variations in LPS sensitivity. However, the LPS sensitive L. lactis subsp. cremoris strains tested did not take up glucose in a PEP depleted state, most likely due to their inability to utilise arginine as an ATP generating energy source. The questions remain unanswered whether cremoris strains possess this glucose transport mechanism and whether it could contribute to strain variations in LPS sensitivity. In a subsequent investigation, galactose phosphotransferase system (PTS) deficient L. lactis strain ATCC 7962 demonstrated log phase growth inhibition when grown on galactose in the presence of the model LPS. Previously reported LPS mediated effects on the glycolytic enzyme hexokinase do not appear to explain this result. The present study confirmed strain variability in sensitivity to the model LPS among both Lactococcus lactis subspecies lactis and subspecies cremoris strains. Further, the observation that dithiothreitol significantly alleviated the inhibition of a highly sensitive cremoris strain, implicated the involvement of sulphydryl groups as the target of the transient inhibitory factors. Data collected excluded the possibility that portions of the metabolic pathways involved in fructose and galactose metabolism are sensitive to the LPS in cells possessing PEP/PTS capability. This study also identified potential directions of further work to elucidate the mechanism(s) of LPS inhibition.
-
ItemTactical choices of medium and high input dairy systems( 2013)In the last decade dairy farms in northern Victoria were exposed to increased volatility of input and output prices as well as variable climate conditions that include a big dry period. Two representative case study pasture based dairy farms of ‘medium’ and ‘high’ input were selected to examine the production and financial outcomes that arise from a multi-year sequence of tactical farm management decisions. The approach of the research had several key aspects; case studies were selected as the method of investigation, on-farm interviews of the case study farmers were carried out and their financial and physical history was collected. A stochastic multiyear whole-farm biophysical and economic spreadsheet model was developed to analyse the physical and economical performance of the case study farms. The study found that both farming systems had different optimum choices available year to year to increase profitability. In many of the scenarios tested, the decision option with the highest growth in equity compared to other options tested did not always result in the highest net cash flow. The decision maker would need to evaluate the net cash flow implications of their decisions to determine if they are worthwhile choices. For both farms, in years with greater upside, there was a greater range of outcomes between decisions compared to years with poor financial outcomes. This suggests farm managers cannot get too relaxed and complacent in the good years and need to ensure they are gaining the benefits of the good year as well as minimizing losses in the poor years.