Effects of dietary vitamin E

Thesis (Ph. D.)--University of Adelaide, Dept. of Animal Science, 1997. / Includes bibliographical references (leaves 186-200).

Thesis (MMedVet. (Production Animal Studies)--University of Pretoria, 2002. / Includes bibliographical references. Also available in print format.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1958. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 122-130).

Thesis (Ph.D.)--University of Missouri-Columbia, 2004. / Typescript. Vita. Includes bibliographical references (leaves 173-181). Also available on the Internet.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1982. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Thesis (M.S.)--University of Wisconsin--Madison. / Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Thesis (Ph.D.)--University of Missouri-Columbia, 2004. / Typescript. Vita. Includes bibliographical references (leaves 173-181). Also available on the Internet.

A series of three experiments were carried out in order to demonstrate an interaction between molybdenum and selenium in broilers. Trail I investigated the interaction of selenium (0, 0.2, 0.4, and 0.8 ppm) with various toxic and subtoxic dietary levels of molybdenum (0, 0.5, 100, and 330 ppm), supplemented to a wheat based diet to broilers from one to four weeks of age. Results indicated that at 300 ppm molybdenum, increasing selenium levels resulted in progressive decline in weight gain, compared to a non-significant decline across these selenium levels when no molybdenum was supplemented. At these levels of molybdenum, selenium appeared to be acting antagonistically with molybdenum. At lower molybdenum levels, selenium exerted no apparent effects on weight gain. Selenium at toxic levels responded different from selenium at subtoxic dietary levels over molybdenum levels. Trial II, used 480 broiler chicks, assigned in a randomized block (RB) experimental design and 12 treatment combinations of selenium and molybdenum. Although the overall interaction effect was non-significant for weeks 1 to 4 inclusive, there were some definite interaction trends. Results indicated that at either basal or 3 ppm Se over basal 100, 200, or 300 ppm Mo, a non-significant difference in weight gain and feed consumption occurred. Selenium and molybdenum appeared to be interacting reciprocally. At 6 ppm dietary supplementation of selenium, however, combining increasing levels of molybdenum appeared to result in an independent toxic effect on weight gain which was additive for the two mineral toxicities, and not interactive. Using 480 broilers chicks assigned to a 3 x 4x3x3 multifactorial arrangement of 12 treatments an experiment was performed to investigate the effect on weight gain and feed consumption upon feeding toxic levels of molybdenum and selenium. Selenium levies ranged from basal, to 6, 12, and 18 ppm and molybdenum levels from basal, 400, and 800 ppm. Treatments were arranged in a RB experimental design. Results indicated that combining toxic dietary levels of selenium and molybdenum resulted in a measurable interaction in birds based on weight gain to feed consumption from one to four weeks of the experimental period. As the toxic dietary levels of selenium increased from basal to 6, 12, and 18 ppm the adverse effect of molybdenum at basal, 400 and 800 ppm became progressively reduced. At 18 ppm selenium, weight gain and feed consumption were the same irrespective of whether basal, 400, 800 ppm Mo was supplemented to the diet. The presence of toxic levels of selenium appeared to either reduce toxicity of molybdenum, or induce an increased tolerance for increasingly toxic levels of molybdenum. The nature of the interaction between selenium and molybdenum is discussed. / Land and Food Systems, Faculty of / Graduate

<p>  </p> <p>This thesis aimed to evaluate the effect of heat treatment of different ingredients on their respective phosphorus digestibility and assess the impact of protein source in the basal diet on the regression-derived phosphorus digestibility methodology. Two studies were carried out to evaluate the objectives.</p> <p>In study 1, regression-derived ileal digestibility and utilization coefficients of phosphorus (P) responses to autoclaving soybean meal (SBM) or poultry meal (PM) were investigated in two experiments. On day 19 post hatching male Cobb 500 broiler chickens were individually weighed and allotted into 6 or 5 treatments in experiment (Exp.) 1 or 2, respectively, in a randomized complete block design, with 8 replicate cages and 8 birds per cage in both experiments. In Exp. 1, diets were formulated with either non-autoclaved or autoclaved soybean meal at 380, 480, or 580 g/kg in a 2 file:///C:/Users/vshae/AppData/Local/Temp/msohtmlclip1/01/clip_image002.png 3 factorial arrangement. Experiment 2 consisted of a basal diet and other four diets, with 40 or 80 g/kg of non-autoclaved PM or autoclaved PM arranged as a 2 file:///C:/Users/vshae/AppData/Local/Temp/msohtmlclip1/01/clip_image002.png 2 + 1 factorial. Chromic oxide was added as an indigestible index marker to determine nutrient ileal digestibility and retention. Birds received the experimental diets for 3 days, and excreta collection was conducted during the last two days. All birds were euthanized by CO2 asphyxiation, and ileal digesta samples were collected. Data were analyzed using the GLM procedure. In both studies autoclaving decreased (<em>P</em> < 0.05) DM digestibility and retention. Increasing the inclusion level of test ingredients linearly increased (<em>P</em> < 0.05) intake of digestible and utilizable P in both studies and linearly reduced the digestibility and retention of DM and P in the soybean meal study. Autoclaving SBM resulted in higher (<em>P</em> < 0.01) ileal digestibility of P and retention of P and Ca. The estimated ileal digestibility of P in SBM, autoclaved SBM, PM, and autoclaved PM were 45, 53.6, 61.2 and 61.2%, respectively, and the corresponding retention were 40.6, 45, 51.7, and 59.2%. Autoclaved SBM tended (<em>P</em> = 0.058) to have higher P digestibility than non-autoclaved, but no effect was noted with PM. These results indicated that autoclaving feed ingredients reduced the digestibility and retention of dry matter, and the digestibility of phosphorus of soybean meal may be improved by heat treatment but not that of poultry meal, which may be due to phytate P degradation.</p> <p>The second study was conducted to evaluate the effect of varying protein sources in the basal diet on the regression-derived P digestibility in soybean meal. This experiment was organized in a 4 × 3 factorial arrangement, consisting of 4 diet types that differed in their protein sources; with the test ingredient as the only source of protein, or with one of 3 protein supplements (casein, potato protein isolate (PPI) or dried egg albumen (DEA)) added at 60 g/kg, and 3 levels of test ingredient (SBM) inclusion at 290, 370 or 450 g/kg. Male Cobb 500 broiler chickens were individually weighed and distributed in the 12 treatments in a randomized complete block design, with 8 replicate cages and 6 birds per cage on day 19 post hatching. Birds were fed the experimental diets for 3 days, and ileal digesta and excreta samples were collected similarly to the first study. Diet type affected (<em>P</em> < 0.01) the digestibility and total tract retention of DM, P, N, and Ca. Diets with added casein presented the highest (<em>P</em> < 0.05) digestibility of P, Ca, and N, retention of P and Ca, and intake of digestible and utilizable P. The digestibility and retention of DM linearly decreased (<em>P</em> < 0.001) with increasing inclusion levels of SBM in all diet types. The estimated ileal digestibility of P in SBM was 56.9, 62.6, 59.1, and 36.4% for diets without protein supplements, with casein, PPI, or DEA, respectively; the corresponding retention of P were 51.7, 82.6, 42.7, and 52.2%. Diet type affected (<em>P</em> < 0.05) the slope and intercept of P digestibility in SBM. A comparison of the coefficients using confidence intervals demonstrated that the ileal digestibility of P in SBM determined in diets with DEA was lower (<em>P</em> < 0.05) than in the other diet types, which were not different from one another. These results indicate that the selection of dietary protein supplements may affect P digestibility essays using the regression method. </p> <p>In summary, the digestibility of P in soybean meal may be improved by heat treatment while not that of poultry meal, which may be ascribed to the higher phytate P content of SBM, and phytate degradation from heat treatment. Results from the second study demonstrated that the protein source, but not level in the basal diet affects the P digestibility of the essay ingredient determined using the regression method. These findings can contribute to reducing P excretion by enhancing the formulation of broiler diets on a digestible P basis, providing information on the effect of heat treatment on dietary P availability, and refining the methodology used to determine P digestibility.</p>