Degree Type

Dissertation

Date of Award

1990

Degree Name

Doctor of Philosophy

Department

Animal Science

First Advisor

Donald C. Beitz

Second Advisor

N. L. Jacobson

Abstract

Thirty crossbred, 8-week-old castrated male pigs were fed diets containing either 20% or 40% of calories as fat as primarily either beef tallow, soy oil, or a 50:50 (wt:wt) blend of tallow and soy oil in a 2 x 3 factorial design. During week 4, common bile duct, duodenal, and femoral arterial catheters were implanted into pigs. After week 6, pigs were injected with autologous low-density lipoprotein (LDL) containing [superscript]3H-cholesterol. During the subsequent 24 hours, total bile output and serial blood and bile samples were collected. Dietary fat source did not affect bile flow rate or concentration of total bile acids, cholesterol, or phospholipids in bile. A newly developed assay used to determine concentration of cholesterol in bile is described. Pigs secreted an average of 16.2% of injected dose of [superscript]3H-cholesterol into bile as bile acids and 4.5% as biliary cholesterol during the 24-hour period. Pigs fed diets containing tallow had greater percentages of palmitoleic and oleic acids and lesser percentages of linoleic and linolenic acids in biliary phospholipids than did pigs fed diets containing soy oil. Hepatocyte membranes collected from pigs fed tallow-based diets had greater percentages of myristic, palmitoleic, and oleic acids and a lesser percentage of stearic acid than did pigs fed diets containing soy oil. Effects of fat source on concentration of cholesterol and total lipid or deposition of LDL-cholesterol in tissues were inconsistent. To study effect of diet on postprandial lipoprotein composition a "12-hour fasted" and 1- and 4-hour postprandial blood samples were drawn at the end of week 6. Cholesterol content of LDL, triacylglycerol, phospholipid, and protein content of high-density lipoprotein (HDL), and triacylglycerol content of very low-density lipoprotein (VLDL) were affected to the greatest extent. Overall, type and amount of fat affected differentially the composition of lipoproteins from postprandial and fasted pigs, with amount of dietary fat having a greater effect than did type of dietary fat. In addition, lipoprotein composition did change with time after a meal but was not affected greatly by type of dietary fat.

DOI

https://doi.org/10.31274/rtd-180813-12489

Publisher

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

Copyright Owner

Cindie Marie Luhman

Language

en

Proquest ID

AAI9100488

File Format

application/pdf

File Size

206 pages

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