School of Agriculture, Food and Ecosystem Sciences - 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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