Typescript. Bibliography: leaves [137]-[157]

Bibliography: leaves 137-156. / xiv, 166 leaves : ill. ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--Dept. of Horticulture, Viticulture and Oenology, University of Adelaide, 1993

Bibliography: leaves 137-156.

The effect of fractionating flax, peas and canola on the digestibility of these ingredients in <i>Nile tilapia</i> was determined. Dehulling of flax, and processing peas and canola to pea protein concentrate and canola protein concentrate, resulted in significant increases in the energy and dry matter digestibilities of these products (P < 0.05). Protein digestibility was significantly improved by dehulling flax but there were no differences in the protein digestibilities of pea, canola and their protein concentrates. The ability of the most digestible ingredients from Experiment 1 to replace fish meal in tilapia diets was examined in a 9 week growth trial. The diet formulations were arranged in a 2 x 4 factorial design with 2 types of plant protein mixtures used to replace fish meal (simple: soyabean meal and maize gluten meal or complex: soyabean meal, maize gluten meal, dehulled flax, pea protein concentrate and canola protein concentrate) and 4 levels of protein originating from fish meal (100%, 67%, 33% and 0%). Diets were formulated to contain equal digestible protein (380 g kg-1) and digestible energy (17.63 MJ kg-1). Fifty six tanks containing 10 male <i>Nile tilapia</i> were used in this experiment. Fish were fed to apparent satiation twice daily for a total of 63 days and growth and feed intake was measured for the entire experimental period. On day 64 of the experiment, one fish per tank was euthanized and a 1 cm segment of small intestine was prepared for measurement of villus length. The average daily gains, specific growth rates and feed efficiencies of fish fed diets with 0% fish meal were significantly lower than fish fed diets with the 33, 67 or 100% fish meal levels. Fish fed the complex diets had significantly higher average daily gains, specific growth rates, feed:gain ratios and protein efficiency ratios than those fed the simple diets. Villus length decreased with decreasing levels of fish meal and increased with increased diet complexity but the effects were not significant. The results indicated that replacement of fish meal with a complex mixture of plant ingredients may allow a greater replacement of fish meal in diets fed to <i> Nile tilapia</i>.

The methylation of specific gene sites is thought to play a controlling role in gene expression in microorganisms, higher plants, and animals. The relationship between methylation of DNA and gene expression has been well documented in microorganisms and animals; however, the regulatory role of methylation in higher plants has remained relatively unresearched. The focus of this study was to investigate fluctuations in DNA methylation during the early development of the pea (Piston sativum).Pea seeds were grown for 12 days (in Vermiculite) in a growth chamber. Duplicate samples of 30 seedlings were harvested daily. The samples were pulse-labeled with S-adenosyl-L-methionine-C3H3 for 10 hr. The labeled methyl group was allowed to be incorporated into the DNA as the samples continued to grow and differentiate. The methyltransferase action was stopped by freezing.DNA was then extracted, purified, and quantitated. Included in the analysis was the quantitation of RNA. The methylation was quantitated through liquid scintillation spectroscopy.Analysis of the fluctuations in the methylation of nucleic acids, over the growth period of seedling differentiation, was done. Methylated DNA was quantitated based on a comparison of radioactivity in extracted DNA minus the radioactivity' attributed to the extracted RNA. Fluctuations in methylation of DNA correlated to the growth patterns observed in the pea seedlings. This study supported the current hypothesis that differentiation in plants may be the result of methylated DNA masking the expression of selective genes. The results suggested that methyl group alterations on RNA follow the DNA pattern and may also play a significant role in gene expression.Ball State UniversityMuncie, IN 47306

The effect of fractionating flax, peas and canola on the digestibility of these ingredients in <i>Nile tilapia</i> was determined. Dehulling of flax, and processing peas and canola to pea protein concentrate and canola protein concentrate, resulted in significant increases in the energy and dry matter digestibilities of these products (P < 0.05). Protein digestibility was significantly improved by dehulling flax but there were no differences in the protein digestibilities of pea, canola and their protein concentrates. The ability of the most digestible ingredients from Experiment 1 to replace fish meal in tilapia diets was examined in a 9 week growth trial. The diet formulations were arranged in a 2 x 4 factorial design with 2 types of plant protein mixtures used to replace fish meal (simple: soyabean meal and maize gluten meal or complex: soyabean meal, maize gluten meal, dehulled flax, pea protein concentrate and canola protein concentrate) and 4 levels of protein originating from fish meal (100%, 67%, 33% and 0%). Diets were formulated to contain equal digestible protein (380 g kg-1) and digestible energy (17.63 MJ kg-1). Fifty six tanks containing 10 male <i>Nile tilapia</i> were used in this experiment. Fish were fed to apparent satiation twice daily for a total of 63 days and growth and feed intake was measured for the entire experimental period. On day 64 of the experiment, one fish per tank was euthanized and a 1 cm segment of small intestine was prepared for measurement of villus length. The average daily gains, specific growth rates and feed efficiencies of fish fed diets with 0% fish meal were significantly lower than fish fed diets with the 33, 67 or 100% fish meal levels. Fish fed the complex diets had significantly higher average daily gains, specific growth rates, feed:gain ratios and protein efficiency ratios than those fed the simple diets. Villus length decreased with decreasing levels of fish meal and increased with increased diet complexity but the effects were not significant. The results indicated that replacement of fish meal with a complex mixture of plant ingredients may allow a greater replacement of fish meal in diets fed to <i> Nile tilapia</i>.

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