School of Agriculture, Food and Ecosystem Sciences - Theses
Permanent URI for this collection
Search Results
1 - 10 of 10
-
Item
-
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.
-
Item
-
ItemAspects of participatory planning with opium growers in Vietnam( 2001)This thesis considers beneficiary participation as a recent innovation in the evolution of international development assistance. International development assistance provided to less developed countries has its origins in the Marshall Plan for the reconstruction of post World War II Europe. The success of this aid led to its application, though the World Bank and other specialist international and bilateral development agencies, directed at economic development rather than reconstruction. The results of adapting development approaches, to require participation of beneficiaries in planning and management, remain controversial, in terms of the additional time, costs, and development outcomes. Although the trend towards participation is gathering pace, even proponents do not agree precisely on the form of participation most appropriate to different situations. This research examines participation in agricultural development in Vietnam in the context of project preparation for a development agency. Two case studies were considered, in which a similar form of participation had been used in initial planning some two years apart, and had continued into implementation of the project in the earlier case. It compared both cases to determine variations in planning approaches and development outcomes that could have been associated with longer exposure to the participatory process in the first case. Although the initial planning ideas expressed by participants were similar in both cases, their ideas differed two and five years apart with iteration of the participatory planning process. It was found that the level of participation achieved in the initial planning was less significant in terms of Arnstein 's ladder than anticipated at the outset and this impacted on the plans made and their achievability over the plan period. Over the following five years, beneficiary participation evolved into a deeper level in the Arnstein (1969) sense when planning was allowed by the recipient Government authorities to result in action. This increasing confidence of beneficiaries, development agents and government officials, informed subsequent cycles of planning and positively impacted on the development outcome. The deeper level of participation was also associated with increased personal and group accountabilities and the increased availability of discretionary government budget for project activities. It was concluded that different perceptions of the purpose of the participation existed both within the external development agency and between it and the recipient Government staff and community leaders. These perceptions resulted from fundamental philosophical differences about the role of community participation in economic development. The research indicates that differing perceptions may be made more congruent and produce a more effective development outcome through use of participatory planning processes. It suggests that lengthy participatory planning in the absence of development action may not result in better development outcomes. In addition it corroborates other findings that projects having repeat phases are likely to be more effective than single phase projects. In terms of practical contribution to development planning the research suggests that it is worth initiating participatory planning processes early in the project cycle, during preparation, to introduce the concepts but the most effective participation is likely to occur during implementation when experience can inform the participatory planning process through participatory monitoring and evaluation. It further suggests that conditional commitment to subsequent phases of projects is desirable from the outset is good development outcomes are to be expected in complex situations such as is the case with opium growers in the hills of Vietnam.
-
Item
-
ItemResponses of young sheep to supplements when fed low quality roughages( 1999)The morphological components of which cereal straw is composed vary in composition and nutritive value. In a survey of relevant literature, stem materials (ST) are usually found to be consumed by ruminant animals at a slower rate than leaf material (LF) from the same crop residues when these are fed alone as separated fractions. This is attributed to the higher content of cell wall constituents (CWCs) and often lower content of N of ST. Because ST and LF can vary in proportions in the roughage fed as a basal feed, the response of animals to supplements might also be expected to be variable particularly when the basal feed is offered in excess that permits selection. In particular the response to supplemental N sources varying in ruminai degradability may vary. The objective of this thesis program was to investigate the interactions between the basal roughage and supplement measured as effects on digestion and LW responses of young sheep. The overall hypothesis was that across diets made up of different proportions of LF and ST fractions of cereal straw, the response to N supplements is dependent on CWCs concentration. The program was completed through a series of experiments conducted at the Mt Derrimut Field Satation of the University of Melbourne. In all experiments the animals were fed on a basal feed of LF or ST fractions of barley straw, with supplements including (a) Bar+USS, barley grain (Bar) fortified with urea solution prepared at a ratio of 5:1 (urea plus Na,SO4). (b) USS, urea solution alone added to the basal roughage and (c) FM, fishmeal. With each basal feed one group of lambs did not receive any supplement and served as a control group (CONT). Experiment 1 (Chapter 3) was conducted to evaluate chemical and nutritional characteristics of straw fractions of Parwon cultivar barley. Straw was separated into 4 fractions - stem (ST), leaf blade (LB), leaf sheath (LS) and broken fractions plus weeds (OT). The separated fractions were analysed chemically ( van Soest, 1974) and in vitro digestibility (Tilley and Terry 1964 ) determined. ST was the largest fraction and contained a significantly higher concentration of neutral detergent fibre (NDF; p<0.01) than LB, LS and OT (83.1, 78.6, 76.8,and 71.5 g/100g respectively). ST contained less hemicellulose (HC) than LB but more than LS and OT (37.5, 39.6, 36.3, and 35.7 respectively). N content was lower in ST than in LB, LS and OT fractions (0.4, 0.9, 0.6, and 0.7 respectively). Digestibility in vitro was significantly lower (P<0.001) for ST than for other fractions (38.5, 72.7, 60.1, and 63.0 respectively) while energy required for grinding (Chenost 1966) was much higher (P<0.001) for ST than for other fractions (121, 54.6, 64.2, 56.6 respectivly). In Experiment 2 (Chapter 4) ST and LF fractions of the same Parwon barley straw were fed as the basal feed to lambs and DM intake of ST was 15% lower than for LF (403 vs 473 g/d). When LF feed was supplemented with USS and FM, DM intake was greater by 28% and 25% respectively, while supplementation with Bar+USS resulted in 10% lower LF intake. In contrast, with animals fed ST as the basal roughage, only FM led to an increase in DM intake of only 10%. Supplementation with Bar+US and USS and FM improved overall digestibility, estimated metabolisable energy intake and N intake. Low N intakes on the basal roughages supported low ruminai ammonia-N concentrations (mg/1) immediately before feeding (ST, 20.4 ; LF 35.8), but these were improved where supplements had been fed with each of ST Bar+USS, 263.7; USS, 186.7; and FM, 151) and LF (Bar+USS, 219.5; USS, 62.5; and FM, 150). Six hours after feeding, ammonia-N concentrations (mg/l)were higher for ST (99) still low for LF(35) when fed alone, reduced below the prefeeding levels by supplements of Bar+USS (ST,167; LF 173) but raised by USS (ST, 201; LF 148) and FM (ST, 114; LF, 192). The concentrations of total volatile fatty acids (VFA) in rumen fluid (mMoUl) were not significantly different for ST and LF before feeding except where FM was the supplement, or six hours after feeding except where Bar+USS or USS were fed with LF (before feeding: ST, 51; Bar+USS, 55.7; USS,46.5; FM, 56 ; LF, 42.6; Bar+USS, 53; USS, 55.5; FM, 63.6; 6h after feeding ST, 55.5; Bar+USS, 70.2; USS, 62.1; FM, 50.4 ; LF, 55.7; Bar+USS, 69.5; USS, 60.9; FM, 60.9). Lambs on ST and LF alone lost weight (ST, -105; LF -98 g/d ). Rate of liveweight loss was less when Bar+USS (ST, -32.3; LF -2.4g/d) and USS (ST, -79.8; LF -31.2 g/d) supplements were fed, while FM promoted LW gain (ST, 37.5; LF, 72.4g/d). N retention data was consistent with these LW gains, except where Bar+USS was the supplement, in which case the animals were in positive N balance though losing weight. Wool growth was significantly improved (P<0.001) only by FM on both ST (+47%) and LF (+57%) basal roughages. In Experiments 3 and 4 (Chapter . 5 and 6) the objective was to investigate the factors responsible for low feed intake and poor performance of lambs fed ST compred to those on LF. The DMI (g/d) of lambs fed ST and LF were similar to those achieved in experiment 2; and were significantly greater for LF (P<0.001). Likewise supplements of Bar+USS, USS and FM had similar effects to those reported for experiment 2_ Changes in DMI, MEI ruminai environment before feeding or 6 and:12 hours after feeding were consistent with those recorded during experiment 2. However concentration of total VFA was significantly elevated at 12 hours after feeding. Differences in ruminal environment were evident in terms of VFA concentrations and the distribution of rumen digesta particulate material in different size fractions; both variables were affected both by the basal diet and the supplement. For LF, the proportions of particles >2mm and of very fine particles (0.125 mm) were greater and for particles between 0.5 and 1 mm less those for ST in all cases. Further, the proportion of particles >2mm was less where FM was fed than for any other feeding regime. The mean retention times of rumen fluid, measured from CoEDTA dilution rate, and calculated for rumen particulate material was longer (24%, P<0.01) for ST than for LF but there was no significant effect of supplement on this (Experiment 4, Chapter 6). The mean percentage of very fine particles in the faeces of lambs fed on LF was higher than for lambs fed ST alone or with supplements. Rate of ruminai degradation of OM of ST and LF as measured by nylon bag technique ( Experiment 3, Chapter 5) was similar at 12 and 24 hours but greater for LF than for ST at 48 and 96 hours of incubation. Bar (cracked whole grain) was degraded more rapidly and extensiveley than FM; in LF fed sheep this difference was more marked. Rate of degradation of acid detergent fibre (ADF) was influenced by the kind of supplement and was greatest in lambs given FM , and least in lambs given ST with no supplement. Only the FM supplement resulted in LW gains, though rates of LW loss were least and LW gains with FM were greatest with LF as the basal roughage. The responses are interpreted as flowing from the greater proportion of ADF and lignin in the CWCs content and the greater digestibility of ADF in the LF fraction. The ST feed fraction with higher concentrations of cell wall constituents (CWCs) as NDF was eaten at a slower rate (Experiment 5, Chapter 7) and digesta particulate material and, in these experiments, the fluid phase are retained longer in the rumen. LF showed not only an advantage over ST in these respects but also in terms of a number of important digestion parameters supported a greater response to supplements, particularly N supplements of low degradability. Thus FM is these experiments interacted with the roughage component of the diet. It provided more consistent ruminai ammonia concentrations supporting a better environment for microbial activity and growth. Microbial protein together with undegraded dietary protein together provide a balance of nutrients that allows LW gains on otherwise submaintenance basal feeds. The greater enhancement of performance with LF compared to ST and the particle size measurements suggest that greater fragmentability of LF may be a major contributor . In terms of technical improvement of livestock feeding systems, providing the animal with opportunity for selection of more leaf and less stem may improve the likelihood of responses to supplements but this was not demonstrated in Experiment 5. FM was used as the experimental supplement to provide slowly degraded and undegraded dietary protein of high biological value to the animal. FM is expensive and other crop byproducts and local feed materials with properties of slow degradability of protein and good amino acid balance need to be identified. An alternative strategy would be to provide a maximum opportunity for the selection of most digestible parts. If refusals are then collected, quality could be further improved with alkali treatment and necessary supplementation. This would provide a strategy for the use of morphological fractions which could be an economical approach for the efficient utilization of roughages.
-
ItemEffects of post-anthesis stress on grain filling and malting quality of barley( 1995)Malting quality is variable from year to year in many countries with Mediterranean or continental climates. Environmental stresses are thought to contribute to that variability. However, little information is available on the relationships between environmental conditions during grain growth and malting quality. Two of the most frequent environmental constraints during grain filling in many cereal-growing areas of the world are high temperature and drought. Short periods (ca. 5 days) of very high maximum temperature (>35C) are quite common during grain growth and have been identified as a potential source of variation in malting quality. Therefore, the main objectives of the present study, were to determine the effect of short periods of high temperature and drought on grain growth and malting quality of barley. The study involved seven experiments, in which short periods (5 days) of high temperature and drought, combined or alone, were imposed during grain filling on the malting cultivar Schooner. Where possible, other malting cultivars were included (Chapters 2 and 3). The effects of short periods of high temperature on grain yield and malting quality of barley were first assessed under field conditions using portable chambers with thermostatically-controlled electric heaters. High temperature imposed for 5 days (17 to 21 days after anthesis) with a maximum temperature of 40C maintained for 6 h per day reduced grain weight by 13% in Schooner and 25% in Parwan. There was a reduction in starch content and an increase in nitrogen content in the heat treatments, but B-glucan content was not affected. High temperature reduced the amount of 'maltable' grain by reducing grain size and increasing screening percentage, and also reduced malt extract by 3-7%, which represents a large decrease for the malting industry. The other experiments in this thesis were carried out under controlled-environment conditions, in order to overcome difficulties of temperature and humidity control. Short periods of high temperature were imposed for 5 or 10 days at mid-grain filling on Schooner and Franklin, with or without drought treatments. Short periods of high temperature reduced grain weight by 5%, while drought reduced it by 20%. High temperature and drought together resulted in the greatest reduction (30%). There was a reduction in starch content and an increase in diastatic power and ?-glucan degradation under stress. However, malt extract was not significantly affected. To determine the importance of timing of short periods of high temperature and drought on grain weight and malting quality, a glasshouse experiment was carried out in which Schooner barley was exposed to these stresses at early, mid or late grain filling. Individual grain weight was most sensitive to high temperature and drought treatments imposed early in grain filling (10-15 days after anthesis) and was less sensitive to later treatments. Starch was reduced in amount and quality, especially with early stresses during grain filling. However, malt extract was not significantly affected. Finally, two experiments were carried out in the Canberra phytotron to study the effects of the temperature regime before and after heat stress on grain growth and quality. In the first experiment, the hypothesis that under a gradual increase in temperature, plants could develop some acclimation was tested. Plants experiencing either a sudden or a gradual increase did not exhibit any differences in grain weight or malting quality, but increasing the temperature in two steps (so that plants were exposed to 30 or 34C for 2 h before a 40C heat stress), appeared to have produced acclimation, since the reduction in grain weight under the two step treatment was about half that of either sudden or gradual increase in temperature. In the second experiment, the hypothesis tested was that grain growth would recover better from short stress under cool (21/16C) than warm (27/22C and 30/250 conditions following that heat stress. The reduction in yield caused by heat stress was not alleviated by the succeeding moderately high temperatures. The following conclusions were derived from this study: (i) the reduction in grain weight ranged from 5 to 35% in response to short periods of high temperature and drought during grain filling in barley. The magnitude of the reduction depended on duration and timing of exposure, (ii) the reduction in grain weight was accompanied by an increase in screening percentage corresponding to a large reduction in amount of 'maltable grain', (iii) grain composition was altered by these stresses, and in general, starch content was most affected. There was a strong and positive relationship between the reduction in grain weight and starch content per grain (R2=0.92, P<0.001). In all the experiments, there were reductions in the volumes of both A- and B-type starch granules; however, the reduction in grain weight was mostly closely related to the reduction in the volume of Atype starch granules. The stress-induced increase in nitrogen percentage was smaller than expected, probably because post-anthesis availability of nitrogen was less limited than under typical field conditions. Grain ?-glucan content tended to be reduced under drought but there was no clear trend under heat stress, and (iv) malt extract was not highly responsive in any of the high temperature or drought experiments. Malt extract was reduced by 3 to 7% in the field experiments (Chapter 2) and by 5% in a glasshouse experiment (Chapter 5) with short periods of heat stress. Although small relative to the grain yield reductions observed, such changes in malt extract are large for the malting industry. High temperature and drought affected several components of malting quality in opposing directions, for example the stresses reduced starch content, which would tend to reduce malt extract but also tended to decrease ?-glucan and increase diastatic power which would tend to increase malt extract. The net result of these opposing changes was generally a minor effect of heat stress and drought on malt extract, even though the main quality components contributing to malt extract often strongly responded to these stresses.
-
Item
-
ItemComparisons of the morphology and physiology of cuttings and seedlings of Eucalyptus globulus( 1994)Eucalyptus globulus subspecies globulus is widely planted for pulp production. It is propagated by cuttings for tree improvement and mass deployment. Development of cuttings and related seedlings was compared to test whether vegetative propagation affects growth adversely. A clone bank was developed from seed and the two best-rooting clones from each of five families compared with seedlings from the same families under optimal, controlled water stress, and field conditions. Cuttings had similar height growth but lower diameter growth rates than seedlings under all conditions. Even under optimal conditions, the morphology of the root systems of cuttings differed from that of seedlings, and cuttings partitioned less biomass to their roots. In all comparisons clones of each family performed similarly to the mean of all cuttings, but variability was high within most clones. Shoot physiology of cuttings and seedlings was similar under optimal and water stressed conditions, but the total water use of cuttings was less than that of seedlings under sub-optimal water availability. Water relations of both plant types were preconditioned by reduced watering frequency; preconditioned cuttings died at higher residual water contents than seedlings, or cuttings watered optimally. Comparisons under field conditions were precluded by early mortality of most seedlings, but the growth and development of the cuttings was monitored for more than one year. Height growth was highly variable within clones and the uniformity expected of clonal plantations was not achieved. Root systems of cuttings and seedlings were fundamentally different. High levels of deformity were observed in the root-shoot junctions of cuttings. These deformities, which imply poor development and instability for seedlings, were not necessarily deleterious for cuttings at 13 months. Accumulated evidence suggested that the root systems of cuttings had poorer uptake and transport capacities. Anatomical examination of the root-shoot junctions showed that the vascular systems were highly distorted. The contortions probably increase resistance in the vascular pathway both by increasing its length and physical resistance. The lack of uniformity within clones was probably due to varying quality of the root systems and suggests the propagation system was inadequate. However, the presence of some individuals which grew similarly to seedlings suggests the propagation system might be modified to produce such plants. In conclusion, it is premature to plant cuttings of Eucalyptus globulus widely until the propagation system is better understood and improved. Long-term monitoring of field plantings is required to evaluate fully the effect of root system morphology and to define the optimal root system for cuttings.
-
Item