Degree Type

Dissertation

Date of Award

1990

Degree Name

Doctor of Philosophy

Department

Animal Science

First Advisor

Donald C. Beitz

Abstract

Fifty-four crossbred, castrated male pigs were fed diets containing either one or three times the daily requirement of calcium and one, five or 25 times the daily requirement of vitamin D[subscript]3 in a 2 x 3 factorial design. During week 6, pigs were fitted with femoral arterial, common bile duct and duodenal catheters. Thirty-six pigs (six/treatment) survived through week 8. Body weight of pigs at weeks 7 and 8 were greater than week 6 weights, indicating that the pigs were growing after surgery. Measurements of plasma triacylglycerol, phospholipid and cholesterol and LDL- and HDL-cholesterol at weeks 6 through 8 showed variable responses to surgery. At week 8, pigs were injected with autologous low-density lipoprotein enriched with [superscript]3H-cholesterol. Blood and bile were collected for 48 hours. Pigs fed excess calcium had less bile flow than did pigs fed recommended amounts of calcium. Bile flow was continuous but variable over the 48-hour sampling period. Pigs secreted 24.6% of injected [superscript]3H-cholesterol into bile as bile acids and 5.6% of injected dose as biliary cholesterol during the 48-hr sampling period. Pigs fed excess calcium had greater concentration of bile acids in bile. Concentration of biliary cholesterol and phospholipid were not affected by dietary calcium. Output of biliary cholesterol, bile acids and phospholipids during the 48-hour sampling period was greater for pigs fed the recommended amount of calicum. Dietary vitamin D[subscript]3 did not significantly affect the bile flow rate or concentration or secretion of biliary lipids. No significant treatment effect was observed on concentrations of lipid in aorta, carcass, liver, muscle, perirenal adipose or viscera samples. Pigs fed excess vitamin D[subscript]3 had less lipid in heart tissue. Treatment effects were not seen for concentration of cholesterol in tissues or percentage of injected [superscript]3H-cholesterol deposited per gram of dry tissue. Aorta sections stained to detect lipid deposition showed traces of fatty streaking. In conclusion, excess dietary calcium caused decreased bile flow, increased concentration of biliary bile acids, and decreased secretion of biliary lipids in young pigs but did not influence cholesterol deposition in tissues. Excess dietary vitamin D[subscript]3 did not affect bile or tissue parameters measured, except for decreased lipid content of heart tissue.

DOI

https://doi.org/10.31274/rtd-180813-12670

Publisher

Digital Repository @ Iowa State University, http://lib.dr.iastate.edu/

Copyright Owner

Stewart Tracy Galloway

Language

en

Proquest ID

AAI9100437

File Format

application/pdf

File Size

129 pages

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