Dissertation - Open Access
Doctor of Philosophy (PhD)
Department / School
Experiments using lambs were conducted to study the effects of buffers or roughages against acidosis occurring during rapid dietary changes. Experiments using rats were conducted to investigate vitamin A and thiamin stability and/or utilization as influenced by bentonite. Incubating rumen fluid in vitro at a pH lower than 6 reduced volatile fatty acid (VFA) production and increased lactate accumulation. Limestone or bentonite at levels of 2% in 92% concentrate diets had little effect on feed intake or rumen and blood parameters during a 7-day treatment period using rumen-canulated sheep. However, 2% NaHCO3 increased rumen pH and feed intake on the third day of high-concentrate feeding. These buffers included in all-concentrate diets in another experiment raised rumen pH and reduced lactate production with little effect on rumen VFA or blood parameters during the first 3 days of concentrate feeding. Alfalfa hay at a 10% level proved to be as effective as the buffers in all criteria. Lambs fed NaHCO3 excreted an alkaline urine compared with an acidic urine for all others. In a digestive trial conducted after 20 days adaptation, dietary buffers tended to increase ration digestibility and fecal pH and reduce fecal starch, but only 2% NaHCO3 improved starch digestibility significantly. Magnesium retention was increased by bentonite, calcium by limestone, and sodium and magnesium by NaHCO3. In another experiment, 2% bentonite or 2% limestone in 92% concentrate diets slightly improved lamb performance during the initial 21 days but were without effect during an extended feeding period. An equal mixture of both buffers at levels totaling 2% and 4% reduced lamb performance. In another instance when lambs were rapidly changed to high-concentrate diets, alfalfa and brome hay at 10% levels reduced acidosis-related death losses from 72% for the controls to 31% for the lambs fed the diets containing hay. Bentonite limited vitamin A utilization by rats with the major loss occurring through adsorption during die t mixing and/or storage. Particle size of bentonite was a main f actor associated with this effect. Complexing bentonite with proteins or nonionic organic materials was highly effective in preventing adsorption of vitamin A by bentonite. Bentonite tended to depress rat growth with a marginal level of thiamin in the diet but not with excess thiamin.
Library of Congress Subject Headings
Lambs -- Feeding and feeds
South Dakota State University
Ha, Jong Kyu, "Studies on Beneficial and Adverse Effects of Dietary Buffers for Lambs" (1981). Electronic Theses and Dissertations. 5821.