Thesis (Ph.D.)--University of Nebraska-Lincoln, 2008. / Title from title screen (site viewed Jan. 13, 2009). PDF text: vii, 268 p. : col. ill. ; 5 Mb. UMI publication number: AAT 3321565. Includes bibliographical references. Also available in microfilm and microfiche formats.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1962. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Thesis(M.S.)--Auburn University, 2005. / Abstract. Vita. Includes bibliographic references.

The effect of orally administered duodenal contents on preventing diarrhea in neonatal calves challenged with enteropathogenic E. coli was studied in a 3 x 2 factorial experiment with five replications. Newborn calves received either 0 or 200 ml of intestinal fluid inoculum, obtained from older milk-fed calves, 2 h after entering the isolation facility. Colostrum was consumed following inoculum administration. The uninoculated calves received colostrum 2 h after entering the isolation facility. In compliance with the 3 x 2 factorial arrangement, two-thirds of the calves received an E. coli challenge 12 or 24 h after colostrum feeding. The remaining calves were unchallenged. Raw milk was fed at the rate of 10 percent of body weight per day. All experimental calves were observed daily for physical condition, percent dry matter of feces, urine output, rectal temperature, and dietary intake. Body weight and packed cell volume (PCV) were determined every third day. Gamma globulin per 100 ml serum was determined at 24 h of age. The inoculum was assayed microbiologically for total anaerobes, anaerobic lactobacilli, total aerobes, coliforms, and aerobic lactobacilli. Twelve calves were slaughtered at seven days of age to determine microbiological populations of the duodenal tissue and digesta. During the first six days of life calves receiving the inoculum exhibited a lower incidence of diarrhea, greater daily urine output, lower PCV, and superior average daily gain as compared to the uninoculated calves. The incidence of diarrhea and its accompanying symptoms were most severe in uninoculated calves challenged at 12 h. Rectal temperature was not affected by treatment. The differences in response to the challenge between inoculated and uninoculated calves for the complete experimental period were similar, but not as great as during the first six days of life. Serum gamma globulin at 24 h of age was abnormally low in inoculated calves. Uninoculated calves possessed normal levels of serum gamma globulin. Bacterial populations of duodenal tissue and fluid of seven day old calves were not influenced by treatment. / M.S.

Calf scours are caused by a variety of infectious agents. Oral rehydration therapy solutions are formulated with the objective of correcting dehydration and acidosis. Currently, oral rehydraton therapy does not promote gut healing in diarrheic calves. However, investigators are examining the role of nutrition in promoting gut healing. Previous work has shown that the amino acid glutamine is important in nitrogen transport between tissues and is an indispensable nutrient for rapidly dividing cells such as lymphocytes, fibroblasts and enterocytes. Small intestinal epithelial cells depend mainly on glutamine, glucose, and ketone bodies for their energy under normal physiological conditions. The oxidative substrate preferred by large intestinal epithelial cells appears to be butyrate, followed by acetate, glutamine, and glucose. Research shows that glutamine supplementation increases intestinal protein synthesis. This may be one of the mechanisms by which glutamine exerts its protective effect on gut integrity and mucosal barrier function during critical illness. However, questions concerning the optimum dose and route by which glutamine is to be administered have yet to be addressed. A surgical model was developed to chronically study the nutrient concentration differences across the portal-drained viscera of preruminant calves. The experimental design consisted of a series of infusions conducted on four different study days in each calf. On the study days, 4 separate 1h infusions of acetate, glucose, glutamine, saline (control) were administered intravenously via the jugular vein at 200 mmol/L/h in a different order. Venous and arterial blood were collected over the last 15 min of each 1h infusion. Blood flow was also measured. Intestinal uptake in ìmol/kg^0.75/min was 0.3 ± 1.1 for glutamine and 1.9 ± 3.1 for glucose during saline infusion. During acetate, glucose, and saline infusions, glucose was a greater source of energy than glutamine for the intestine. However, during glutamine infusion, intestinal glutamine uptake (29.9 ± 11.2 ìmol/kg^0.75/min) increased significantly which was associated with a rise in ammonia production (7.0 ± 0.5 ìmol/kg^0.75min). A second experiment was designed to determine if glutamine uptake could be further stimulated either by longer term intravenous infusion or by chronic oral supplementation in neonatal calves. Intestinal metabolism was investigated by measuring nutrient uptake during three intravenous infusions of glutamine over a 5 h period after an overnight fast. Prior to the first infusion, calves diet consisted of milk only. Diet was supplemented with oral glutamine for the second and third infusions. Glutamine was administered via the jugular vein at a rate of 200 mmol/L/h. Venous and arterial blood was collected in duplicate every hour for 5 h. Blood flow was also measured. During glutamine infusion, there was an absolute increase in PDV uptake of glutamine associated with a significant production of ammonia. Feeding glutamine orally did not alter the PDV glutamine uptake. Glutamine infusion did not increase the intestinal uptake of essential amino acids. Neither chronic oral supplementation with glutamine, or infusion for periods longer than an hour, further increased intestinal glutamine uptake. Arterial leucine concentration and intestinal uptake declined during glutamine infusion suggesting that its supply became limiting. Thus glutamine supplementation may require the provision of a mixture of amino acids to be effective.