Call number: LD2668 .T4 1965 M958 / Master of Science

LD2668 .T4 1966 C58 / Master of Science

Call number: LD2668 .T4 1978 A23 / Master of Science

Call number: LD2668 .T4 1979 M67 / Master of Science

Call number: LD2668 .T4 1952 S96 / Master of Science

Call number: LD2668 .T4 1965 H35 / Master of Science

published_or_final_version / Zoology / Doctoral / Doctor of Philosophy

The lipid composition of swine is characteristic of the species and is also a reflection of their dietary history. Other investigators have established that the physical properties and composition of swine depot fat may be altered by variation of the dietary lipid. Dietary regimens employing vegetable oil-bearing materials and their effect on meat quality has received the attention of animal nutritionists for a considerable period. Less is known about the nutritive value of the more highly unsaturated lipids, such as fish oils, and their effect on the lipid composition of swine tissues. Even less is known about the fate of oxidized fish oil lipids in swine rations. This research had for its purpose the investigation of the fate in swine of the dietary marine lipid, menhaden oil, and its effect on composition of depot lipids. The state of autoxidation of the oil and the effect of certain antioxidants on the fatty acid composition of swine was determined. Growth studies on swine were made using menhaden oil of various oxidation states as the dietary lipid. The effect of antioxidants, ∝-tocopherol acetate and ethoxyquin, was also investigated. At the conclusion of the diet trials, tissue samples, representing the five dietary regimens, were removed for analysis. The fatty tissues examined were outer back fat, inner back fat, and kidney fat. Samples of liver tissue for lipid analysis were also taken. The lipids from the respective tissues were extracted and interesterified with methanol to yield the methyl esters of the fatty acids. Hydrogenation of the unsaturated methyl esters for chain length confirmation was carried out. Qualitative and quantitative gas-liquid chromatographic analysis of the unhydrogenated and hydrogenated methyl esters of the fatty acids were performed on diethylene glycol succinate column. The results of these investigations showed that a particular dietary fatty acid can be selectively deposited in animal tissues. Long chain polyunsaturated fatty acids of menhaden oil, such as 20:5, 22:5, 22:6 were sparsely deposited in adipose tissues. The depot fat composition showed a mixture of characteristic menhaden oil fatty acids with the typical fat synthesized by swine. Fatty acid composition of tissue from swine fed oxidized menhaden oil with and without antioxidants showed very similar fatty acid composition as those fed fresh menhaden oil. The results of this investigation supported the beneficial effect of vitamin E (∝-tocopherol acetate) and ethoxyquin as in vivo antioxidants. / Graduation date: 1964

No description available.

I consider two types of foraging situations. In the first type, the forager knows the location and quality of no more than one food item or habitat at a time. I call this myopic foraging. In the second situation, the forager may know the location and quality of more than one food item or habitat at a time. I call this periscopic foraging. I develop theoretically both models and the predictions generated by each. Myopic models predict that foragers should have a so-called "bang-bang" control with respect to the choice of food types. Periscopic models predict that foragers will have a continuous control with respect to the choice of food types. I experimentally tested for the presence of each type of control in a field study that employed hummingbirds feeding on artificial resources. As predicted by the theory, the transition of behavior from picky to opportunistic was significantly sharper for the myopic than for the periscopic foragers. Furthermore, theory predicts that there should be some range of relative values of the rich and poor food types over which the myopic foragers are opportunistic, while the periscopic foragers exhibit a partial preference. This prediction was supported by the data. I predicted that the partial preferences of periscopic foragers would result from the hummingbirds exploiting those poor quality feeders which were located nearest to the best foraging path among rich feeders. The data supported this prediction. Periscopic foragers also performed as predicted by becoming more selective on rich feeders as the densities of both rich and poor feeders increased. I developed a model of optimal sampling behavior that hypothesized birds have evolved in an environment of exploitative competition. The model predicted a rule of departure from a resource patch that depended on the presence or absence of nectar in a sampled as well as the expected quality of the nectar. Hummingbirds performed according to the model's predictions.