Degree Type

Dissertation

Date of Award

1984

Degree Name

Doctor of Philosophy

Department

Animal Science

Abstract

Two trials were conducted to examine the effects of restricted (approximately 65% of ad libitum intake for 8 weeks) and liberal (approximately 90% of ad libitum intake for 7 weeks) feeding of isonitrogenous, isocaloric beef-based, soy-based, and conventional swine diets on growth and cholesterol and triglyceride metabolism in young pigs. In both trials, beef-fed pigs had greater rates of gain than did conventionally-fed pigs; soy-fed pigs were intermediate. Pigs fed the high-fat, high-cholesterol beef and soy diets had greater concentrations of free fatty acids, triglycerides, and total, HDL-, and LDL-cholesterol in plasma in both trials than did pigs fed the low-fat, cholesterol-free conventional diets. Beef-fed pigs had greater total, HDL-, and LDL-cholesterol concentrations in plasma than did soy-fed pigs in the second trial. Soy-fed pigs deposited more fat in the body than did conventionally-fed pigs in both trials and beef-fed pigs in the first trial. Differences between dietary groups in growth and body composition seemed to be the result of differences in nutrient absorption and partitioning. The greater fat content of the beef and soy diets, when compared with the conventional diets, suppressed lipogenesis from glucose in adipose tissue slices in both trials. In the first trial, soy-fed pigs tended to have greater lipogenic rates in the whole body than did beef-fed pigs, which reflected and probably gave rise to greater fat deposition in the soy-fed pigs;Soy-fed pigs had two- to three-fold greater cholesterol concentrations in the whole body than did conventionally- or beef-fed pigs, respectively, in the first trial. In the second trial, soy-fed pigs had greater cholesterol concentrations in the whole body and also excreted greater amounts of bile acids and neutral steroids than did beef- or conventionally-fed pigs, which did not differ in these parameters. Thus, the beef diet, but not the soy diet, seemed to suppress cholesterogenesis so that cholesterol deposition and excretion were similar to those of conventionally-fed pigs. Although both high-fat, high-cholesterol beef and soy diets increased plasma cholesterol concentrations when compared with low-fat, cholesterol-free conventional diets, only the soy diets produced greater amounts of cholesterol in the entire body.

DOI

https://doi.org/10.31274/rtd-180813-5301

Publisher

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

Copyright Owner

Deborah Ann Diersen Schade

Language

en

Proquest ID

AAI8423741

File Format

application/pdf

File Size

268 pages

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