Agriculture and Food Systems - Theses
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ItemA study of the effects of high stocking rates on the production of perennial pasture and its utilization by dairy cattle( 1973)The work in this thesis consists of a study of the effects of increasing the stocking rate from 2.2 to 3.2 cows per hectare on the production of dairy cattle and perennial pastures from 1966-70. (a) Milk production per cow was significantly reduced (P < 0.05) by the increase in.:stocking rate with the exception of the first year. (b) The yield of milk and milk components per hectare was increased (P< 0.05) by the increase in stocking rate except for 1968-69 when a drought occurred and the increases were not large enough in most components to attain significance (P)00.05). The yield of nitrogen in milk per hectare was significantly increased (p<0.05) in all years with stocking rate. (c) There was a tendency for the high stocking rate to lower the percentage of all components in milk with the exception of nitrogen which remained unaltered. However significant differences were not recorded consistently in any one component over the four lactations studied. (d) No significant differences (p>0.05) in seasonal or annual net pasture production were recorded between stocking rates. (e) The increase in stocking rate caused significant increases (1).<0.01) in grazing pressure, reductions in pasture availability (P<0.01) and higher contents of crude protein (1).<0.01) in pasture excepting spring and on two occasions in winter. (f) Estimates of feed intake at the higher stocking rate showed a significant increase in pasture harvested (P < 0.01) per unit area every year. However with the exception of the first year feed intake per cow was significantly reduced (P<0.01). (g) The ratio of pasture consumed per hectare to milk production per hectare was not significantly affected (P>0.05) by the increase in stocking rate.
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ItemSome effects of botanical composition of pasture on the liveweight and wool production of sheep( 1972)Until recently, the main evidence on which to base pasture mixture. recommendations in Victoria, has been district experience and the results from dry matter ( "mowing") experiments. The grazing experiments described in this thesis, were initiated by Messrs. R. Twentyman, R. Newman, R. Allen and K. Maher of the Department of Agriculture during the period, 1960-196. Their aim was to develop some objective appreciation of the relative value for animal production of some of the sown and unsown species in Western district pastures. In addition to pasture species evaluation, they sought information on the relationship between pasture growth and animal production. Such information is needed so that Agrostologists can better evaluate the many pasture management factors (such as fertilizers, seeding rates, seed. treatments, herbicides, insecticides and defoliation treatments) that affect pasture growth and for which advice is frequently sought.
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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.
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ItemStudies on metabolizable energy values of poultry feedstuffs( 1974)This thesis describes studies carried out on metabolizable energy values of a number of feedstuffs available in the State of Victoria for poultry nutrition. These investigations were part of a research project in the poultry research section of S.S.Cameron Laboratory (Animal Research), Werribee. I was responsible for the design and execution of the experiments and for all chemical analyses. The statistical analysis was done by Mr. Jardine, Biometrician, Department of Agriculture, Melbourne. The interpretation of the results and the preparation of the review and the manuscript have been my responsibility. Chapter 1 includes a literature review of the different methods that are used in determining metabolizable energy values for poultry as well as the factors that may affect the metabolizable energy content of diets and feed ingredients. Chapter 2 describes the general procedure of the metabolizable energy assay. The specific material and methods of the experiments were included in each of the experimental chapters. Chapter 3 outlines the balance studies carried out to determine metabolizable energy values of various feedstuffs with different sexes. A comparison between the biologically determined values and those calculated from the chemical composition of the feedstuffs also was included. Chapters 4, 5 and 6 concern the investigations carried out to study the effect of sex of chicks on metabolizable energy content of soyabean, rapeseed, fish meals, tallow and sunflower oil at various levels of inclusion in diets. Chapter 7 summarises the results obtained and recommended avenues for future work. Note: The experimental chapters (3-6) are presented in the format required for publication in the Australian Journal of Experimental Agriculture and Animal Husbandry.
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ItemThe utilization of livestock wastes by ruminants( 1975)In studies with sheep faeces it was found that the longer the faeces were stored,the lower the content of moisture, crude protein and ether extract and the higher the content of nitrogen free extract. Crude fibre and ash contents were relatively constant. The in vitro technique and the in vivo nylon bag technique to estimate dry matter digestibility (DMD) and organic matter digestibility (OMD) of excreta were investigated. Using an oven as an incubator in the in vitro technique, DMD and OMD coefficients of the faeces of sheep, cattle, pig and the manure of poultry were 19.2, 18.9, 45.7 and 62.6,and 10.9, 8.6, 28.2 and 30.7, respectively. Using a waterbath as an incubator DMD and OMD coefficients were 18.8, 16.8, 31.3 and 53.7,and 17. 0, 14.6, 28.0 and 48.2, respectively. The different techniques are discussed. The in vivo nylon bag technique using nylon "A" in sheep and using nylon "A" and "B" in cattle was carried out for 24, 48, 72 and 96 hours incubation periods. DMD and ODM coefficients are recorded, and the procedures are described. The effects of continuous feeding for 70 days of dried pig faeces, supplemented in the diet of 21 sheep were studied. Seven dietary treatments were imposed. Diet A was a pelleted medium quality hay containing 10.3 mg Cu/kg DM and 0.2 mg Mo/kg DM. Diets B,C and D contained 15% pig faeces which gave a dietary Cu concentration of 101.3 mg/kg; molybdenum was added to diet C to give a concentration of 90 mg/kg DM and to diet D to give a concentration of 175.5 mg/kg DM. Diets E, F and G contained 30% pig faeces (192.5 mg Cu/kg DM) ; molybdenum was added to diet F to give a concentration of 90 mg/kg DM, and to diet G to give a concentration of 175.5 mg/kg DM. Sulphate was added to all diets at the rate of 1.08% of the dry matter. During the experiment all animals survived. Inclusion of dried pig faeces in the diets reduced the digestibility compared with the control diet. The maximum plasma GOT activity detected was 182 units/ml reading at 505 nm wavelength. Blood Cu concentrations ranged from 0.28 ug/ml to 3.50 ug/ml. Wool Cu concentration ranged from 2 to 8 mg/kg DM. Kidney Cu concentration ranged from 19.2 to 190 mg/kg DM. Over the 70 days of the experiment, the Cu retention for groups A - G were, respectively, 210 + 17, 680 + 149, 1191 + 39, 1054 + 20, 53 + 185, 1079 + 164 and 1225 + 157 mg. Liver Cu concentrations were, respectively, 718 + 174, 1186 + 176, 1440 + 248, 1522 + 477, 1740 + 212, 1560 + 46 and 1703 + 384 mg/kg DM. There was no correlation between total Cu intake and Cu retention in the body. However, there was a relationship between total Cu intake and liver Cu concentration ( r = 0.827 ) and between total Cu intake and faecal Cu concentration ( r = 0.997 ). Almost all of Cu output was excreted as a faecal Cu. Histopathological examination showed variable liver damage with some sheep showing single cell necrosis , particularly in the livers of sheep receiving 30% dried pig faeces in the diets. No kidney abnormalities were found. It was concluded that pig faeces, with no processing other than drying, are poorly utilized in the diet of sheep and with continuous feeding may induce copper toxicity.
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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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