School of Agriculture, Food and Ecosystem Sciences - Theses
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ItemMeasurement of the degree of cell rupture in macerated lucerne( 1978)Cell rupture is a critical process in the fractionation of green crops. Despite the importance of this process there is no accepted method for quantitatively describing the degree of cell rupture in a sample of macerated forage. Several methods were investigated and developed as measures of the degree of cell rupture in samples of lucerne leaves macerated by extrusion:- (i) Separation of cells and enumeration of intact cells. (ii) Release of cellular substances:- (a) water soluble carbohydrates (b) potassium (c) sodium (d) electrolytes (e) water (iii) Standard juice expression technique as used by other workers. A total rupture standard was considered to be essential, and was achieved in samples of lucerne leaf tissue macerated initially using a mortar and pestle, followed by ten minutes exposure to ultrasound. The performance of these techniques was evaluated in terms of repeatability and of individual and comparative performance over a large range of degrees of maceration. The cell enumeration method was not developed because a suitable agent for separating the cells of lucerne leaf tissue could not be found. All substance release assays gave repeatable estimates of cell rupture and were highly correlated with each other. It was therefore concluded, that the release of cellular substances gave a reliable estimate of the degree of cell rupture. The standard juice expression technique was insensitive to changes in the degree of rupture and was inaccurate at high levels of rupture. It was concluded that the electrolyte release assay was the most appropriate estimate of cell rupture for use in the future.
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ItemVegetative and sheep production on a semi-arid Danthonia caespitosa (Gaudich) -Stipa variabilis (Hughes) grassland in response to fertilizers and deferred grazing( 1977)The initial and residual effects of nitrogen and phosphorus fertilizers applied over four consecutive years and gypsum applied once only, were assessed on a Danthonia caespitosa - Stipa variabilis grassland, growing on the semi-arid Riverine Plain of south-eastern Australia. The treatments were combined factorially. The residual effects were assessed over a five-year period from when the fertilizers were last applied. Totals of 155 and 310 kg ha-1 of N, 100 and 200 kg ha-1 of P, and 3.34 and 6.68 tonne ha-1 of CaSO4.2H20 had been added. Seasonal production of total dry matter and individual species, and nitrogen and phosphorus contents of the plant tops, were measured. A simultaneous, but separate, study was made over five years of the effects of nitrogen and phosphorus fertilizers and deferred spring grazing on the bodyweight and wool production of Merino wether weaners grazing a D. caespitosa - S. variabilis grassland at three stocking rates. Seasonal forage availability, botanical composition of forage, bodyweight and wool growth of sheep, were measured. Two years after grazing treatments ceased, and three years after the final addition of fertilizer, further measurements were made on the vegetation. In the first study, during the four years of fertilizer application, forage production increased in response to the additives in years in which the annual rainfall varied from well below to near average. They accentuated the normal pattern of a spring peak, but also gave lesser increases in production in winter and autumn. Summer production was not measured because of the absence of effective summer rainfall. Nitrogen and phosphorus fertilizers and gypsum all contributed to the increased production, and the combination of the three additives produced the greatest yield. Over all seasons the yield of grassland treated with nitrogen plus phosphorus plus gypsum averaged 250 per cent of the control, or approximately 1,500 kg ha-1. The main contributors to increases in yield were D. caespitosa, S. variabilis, annual herbs, and legumes. The perennial grasses were particularly favoured by nitrogen fertilizer whereas the yield of legumes was suppressed. The yield of legumes increased greatly in response to phosphorus fertilizer. With the exception of two species, all plants which increased in yield are acceptable to sheep. Nitrogen and phosphorus contents were above the minimum requirements for domestic herbivores. The study of the residual effects revealed that the increase in dry matter production in response to nitrogen ceased one year after the last application of nitrogen fertilizer. After five years, grassland which had received 200 kg ha-1 of phosphorus and 6.68 tonne ha-1 of gypsum yielded 6,500 kg ha-4 of dry matter, compared with 1,300 kg ha-1 in the absence of fertilizers and gypsum. Legume growth was still suppressed five years after nitrogen fertilizer had been applied, whilst legumes increased production greatly in response to the previous phosphorus and phosphorus-gypsum treatments. Nitrogen content of the herbage averaged 2.1 per cent four years after the previous high level phosphorus treatment, compared to 1.6 per cent with the control after four years. It was unaffected by previous nitrogen fertilizer. Phosphorus content was reduced for the first three years after nitrogen fertilizer was last added, but was increased by phosphorus fertilizer to 0.28 per cent, compared with 0.18 per cent on the control, four years after phosphorus fertilizer was last added. Soil moisture characteristics, and total soil nitrogen and carbon showed no differences between treatments. The Truog phosphorus in the soil under the high phosphorus level decreased from 103 ppm to 53 ppm, compared to the unaltered control level of 7 ppm over the five year period. In the grazing experiment there were very few differences in plant and animal response between the continuously and deferred grazing systems. Forage availability increased on fertilized grassland at all stocking rates by up to 50 per cent. D. caespitosa, S. variabilis, perennial chenopods, and annual herbs contributed to the increase in forage present. Medicago polymorpha became prominent on all fertilized grassland. At 2.0 and 2.7 sheep ha-1 without fertilizer, and 2.7 sheep ha- 1 with fertilizer, the relative contribution by the more palatable species decreased and EriochIamys behrii increased greatly. After grazing treatments ceased, this trend was reversed. Sheep bodyweight and wool growth rates were increased on fertilized grassland. In September 1971, at 2.0 sheep ha-1, the bodyweights of sheep on unfertilized and fertilized grassland were 35.0 and 45.2 kg, respectively, and the clean fleece weights were 3.2 and 4.3 kg per sheep, respectively. Animal production from this grassland can be increased with the addition of fertilizer to the grassland and by increasing the stocking rate by about 50 per cent above the district average of 1.2 sheep per hectare.
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ItemWhole grain for beef cattle( 1979)This thesis consists of a review of feeding processed versus non-processed grain to cattle and reports on several investigations concerned with feeding whole cereal grain to cattle. The experimental section represents a sequence of investigations which attempts to fill information gaps highlighted by the preceding review. They have been prepared as scientific papers and all have been either published or presented for publication. For presentation in this thesis, all have been typed in the one format. I was actively involved in the field work at the Rutherglen Research Station during these investigations, carrying out all of the physical analyses and most of the chemical analyses that were required. I was also responsible for the collation, analysis and interpretation of all the data and the reporting in the scientific papers.
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ItemThe training needs of agribusiness in Australia : a commodity systems approach( 1978)Adopting the concept of agribusiness and the commodity systems approach, this study was conducted to assess the in-service training needs of the human resources in the wheat and the beef commodity systems of Victoria. Having defined the two selected commodity systems in their macro environment, the study concentrated at the level of the individual organization to determine the training needs for the managerial, the professional, and the sales staff. A mail questionnaire survey was conducted with a multi-cluster sampling technique amongst 708 agribusiness organizations in Victoria and a final response rate of 57% was achieved. The findings of this exploratory study indicated: (1) that there were no appreciable differences in the expressed training needs between the two commodities studied (wheat and beef), and amongst the three staff categories (managerial, professional, and sales staff) investigated; (2) that there was a higher level of need for management knowledge rather than for production knowledge; (3) that courses offered by Technical and Tertiary institutions in Victoria in the area of agribusiness were not recipient-oriented, and were seen as unsuitable for their needs; and (4) that the demand for communication training seen in terms of potential staff-numbers was considerable. Some suggestions regarding the implications of these findings have also been made to meet the training needs revealed by the study.
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ItemMeasuring and improving work performance in milking systems( 1977)Milking represents 40-50% of the total labour input into Australian dairy farms. Unless this work input can be reduced, the job of milking will remain a major limitation to improvements in the efficiency of dairyfarming. The main aim of the field study reported in this thesis was to study the milking and cleaning performance of 15 of the 24 rotary milking systems operating in Australia in the Spring of 1973. Elements of the work routine time were analysed to measure: (a) the relative effects on milking throughput of alternative shed designs, operating systems and types of automation; (b) the relative influence of yard design, shed type, and the operator, on the ease and speed of cow movement from the cowyard onto the rotary platform; and (c) the labour requirements and relative effectiveness of different cleaning systems. Measurements were made at one evening milking and the following morning milking at each farm by 2, 3 or 4 observers, using multi-channel event recorders, stop watches and. recording sheets. Although changes in the element times of the work routine occurred as milking progressed, the labour productivity '(cows milked per man hour) did not change significantly during milking in the group of rotaries studied. Labour productivity was lower at morning milkings than at evening milkings. Productivity increased with increasing number of milking units per operator and, to a lesser extent, with the degree of mechanisation used. The time taken to move cows onto the rotary platforms increased towards the end of milking. The operators increased involvement in cow movement later in milking was partly compensated for by a decrease in his idle time. Operators rated as good, cowmen spent less time encouraging, forcing or assisting cows onto the platform than those operators rated as below average cowmen. Cows defecated less on "turnstyle" type rotary platforms than on rotary herringbone platforms which had no provision for head yoking of the cows. Although there were no significant differences in "cow-in" times or percentage of cows needing assistance onto the platform between circular and rectangular type holding yards, cow behaviour was slightly better in the group of rectangular yards studied. Mechanisation substantially reduced the amount of time spent on cleaning milking machines. It is clear that all milking systems have considerable potential for mechanisation. The amount and type of labour saved must establish the priorities put on mechanising the' various tasks involved in milking and cleaning. Mechanisation of the milking routine is pointless unless there is a corresponding increase in the number of milking units per operator. Techniques for data collection and presentation must be simplified and standardised to enable comparison of results between surveys and between milking systems, e.g. throughput should be expressed as cows per man hour per milking unit as well as cows per man hour, to permit meaningful comparisons. Good cowmanship is critical to the success of a milking system. "Cowmanship" needs to be clearly defined and. further investigated. Variations in milker and cow behaviour in the milking systems studied in the survey indicate that the principle of shifting the emphasis from one of forcing cows to conform, to one of encouraging them to ca-operate by conditioning and training, warrants further research
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ItemThe effect of applied N and P under mowing and grazing on the yield and botanical and chemical composition of irrigated pasture and on the nutrient status of a red-brown earth at Kyabram( 1978)A split plot experiment was conducted over 4 years to study the effect of method of harvesting (grazing and mowing) and applied N and P (5 rates of nitrogen ranged from 0 to 112 kg N ha -1 cut-1 and 6 rates of superphosphate ranged from 0 to 188 kg P ha 1 year year-1) on the yield, botanical and chemical composition of irrigated phalaris (Phalaris tuberosa x Phalaris arundinacea)/white clover (Trifolium repens L. cv. Irrigation) pasture and nutrient status of a red-brown earth at Kyabram. A second experiment was conducted over 2 years to find out the effect of rates (0 to 112 kg N ha. 1) and frequency of N application (2, 4 or 8 times year ) o n dry matter production, botanical composition and crude protein content of paspalum (Paspalum dilatatum)/white clover pasture. Results: Mowed plots significantly out-yielded grazed plots in the first two years. However, grazed plots significantly out-yielded mowed plots in the following two years. Nitrogen application significantly (P <0.01) increased dry matter production of grass/clover mixtures. The size of response was governed by the growth rate of pasture species, clover percentage in the sward, climatic conditions and the status of other nutrients in the soil. Splitting N rates in smaller but more frequent applications had no effect on total herbage yield or seasonal distribution. Response to N (kg D.M. kg N-1 ) declined as N rates increased. Phosphorus application up to 94 kg P ha -1 year -1 significantly (P,(0.01) increased pasture production and relative response was greater in winter. Occasionally, the P and N requirements for maximum production were higher for grazing than for mowing. Both methods of defoliation and fertilizer applications affected pasture composition and IT, P and K content in the herbage. Nitrogen application decreased N in the herbage before increasing it and P application up to 141 kg P ha- 1 year -1 increased it. The return by the grazing animal increased total soil N by 106 kg ha 1 year 1 and soil P (Colwell) by 1:0 p.p.m. in four years compared with the start of the experiment. The relationship between plant P and soil P and P rates were significant (P < 0.01). The available soil P decreased with P withdrawal or the application of 23.5 kg P ha-1 year -1 under grazing and 47 kg P ha -1 year-1 under mowing. Phosphorus and nitrogen application significantly affected available soil P. 60-80% of the available P accuminulated in the 0-5 cm and the downward movement increased by increasing P rates. The continuous mowing and P application significantly reduced available soil K. Defoliation method affected C/t:N ratio. Phosphorus application increased soil N whereas N application decreased it. P application at the rate of 23.5 kg ha-1 year-1 increased total soil N by 0.068% which is equivalent to 952 kg N ha-1 in five years. It was estimated that 4 to 4.7 p.p.m of P was required to be removed or added to the soil to change the available soil P by 1 p.p.m. The application of 196 kg N ha-1 year -1 as NH4 NO3 did not change the soil pH and 784 kg N ha 1 year 1 reduced soil pH by an average of ').4 unit.
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ItemThe ability of sheep and goats to utilize crop by-products( 1977)Two digestibility trials and one feeding experiment were implemented. In the first digestibility trial sheep were fed rations of hay to which was added (w/w} 10%, 20% and 30% of rice bran, soybean meal and cassava respectively. The results showed that changes in digestibility were not directly proportional to the amount of the ingredient added, thus the individual analysis or digestibility of a single food does not necessarily indicate its feeding value in mixed diet. In the second trial the digestive efficiency of sheep and goats was compared when fed low, medium and high quality diets as represented by oat straw, meadow hay and sheep fattening pellets. For all practical purposes the sheep and goats were similar in their ability to digest all diets but there was some evidence to show that the goats made better use of crude protein in the oat straw and crude fibre in the pelleted diet. In the feeding experiment the same by-products that were used in the first digestibility trial were variously combined to investigate the best mixture for fattening sheep. The best liveweight gains were obtained from diets D2 and D3. D2 contained 33% hay, 30% rice bran, 25% cassava and 12% soybean meal.' D3 comprised 40% hay, 15% rice bran, 30% cassava and 15% soybean meal.
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