Effect of soy versus beef diets on blood and tissue cholesterol and body composition of growing swine

Influence of two dietary fats on the composition of emu oil and meat

Male and female emus were fed a diet rich in saturated fat (beef tallow) or a diet rich in unsaturated fat (soybean oil) until they weighed about 35 kg. Samples of subcutaneous and retroperitoneal adipose tissues and samples of six major meat cuts were taken for determination of composition. Emus fed the two different diets grew at similar rates, but the male emus had a higher percentage of carcass fat. The adipose tissue cells from males were larger than those from females. All six meat cuts averaged 2.2% fat, with the regular filet having the most and the inside and outside drums the least. Cholesterol concentration of all sizes of meat cuts averaged 32.2 mg/100 g meat. Diet did not influence cholesterol content of the rendered oil. Fan filets had the greatest concentration of cholesterol, and the inside and outside drums had the least. Source of dietary fat had no effect on fat and cholesterol content of the meats. Meat from emus fed beef tallow was more tender and juicy. Fan filets were the most tender meat, had the least intense flavor, and were the most flavorful. Untrained panelists were able to discriminate between emu meat and beef. Source of dietary fat did not influence the fatty acid compositions of the meats. As expected, the soybean oil-fed emus produced oil that was more polyunsaturated than did the tallow-fed emus.

Effects of dietary beef and soy protein on tissue composition and low density lipoprotein uptake in young pigs

To study effects of dietary protein source on plasma cholesterol homeostasis, six littermate pairs of 8-wk-old, castrated male pigs were assigned randomly to high fat diets containing either lean beef or soy protein isolate, with beef tallow as the major fat source in both diets. Diets were fed for 6 wk, with blood samples taken weekly and analyzed for lipid composition. At 6 wk, each pig was injected with [3H]cholesterol- and [14C]sucrose-labeled low density lipoproteins, and serial blood samples were taken. Pigs were then killed, and several tissues were sampled. Results show that dietary beef or soy protein, when fed with beef tallow as a fat source, has differential effects on rates of uptake of intact LDL by heart, M. sartorius muscle and subcutaneous adipose tissue, and on rates of uptake of LDL cholesterol by net free cholesterol exchange in subcutaneous and perirenal adipose tissues. Dietary protein source affected the composition of only two tissues analyzed. Pigs fed the beef-based diet had greater lipid concentrations in M. sartorius muscle, whereas pigs fed the soy protein-based diet had greater lipid concentrations in heart. Source of dietary protein did not influence in vivo kinetics of LDL cholesterol removal from blood plasma.

Plasma, tissue and fecal cholesterol of young pigs fed restricted or liberal amounts of beef, soy or conventional diets

Cholesterol disposition (tissue deposition + fecal excretion) was determined in young pigs fed restricted (trial 1) or liberal (trial 2) amounts of beef-based, soy-based or conventional swine diets. Cholesterol content of diet is greater than average United States consumption per kilogram body weight but is very similar on a per-kilocalorie intake basis. Both beef and soy diets contained more cholesterol (0.09% by weight vs. 0%) and fat (40-50% of calories vs. 8-9%) than did conventional diets. Dried egg yolk was the source of cholesterol in the soy diets. Beef- and soy-fed pigs had greater plasma, HDL and LDL cholesterol concentrations than did conventionally fed pigs; beef-fed pigs had greater plasma, HDL and LDL cholesterol concentrations than did soy-fed pigs in trial 2 only. Final HDL-to-LDL cholesterol ratios did not differ. Neutral steroid and bile acid excretion was twofold greater in soy-fed than in conventionally or beef-fed pigs in trial 2 only. Differences in cholesterol concentrations were found in liver (soy, beef greater than conventional) and heart (soy greater than beef, conventional) in trial 1 and in liver (soy, beef greater than conventional), adipose tissue (soy greater than conventional greater than beef) and aorta and other viscera (conventional greater than soy, beef) in trial 2. In both trials, soy-fed pigs had greatest whole-body cholesterol concentrations. Thus, in both trials, disposition of cholesterol was similar in conventionally fed and beef-fed pigs, despite greater cholesterol intake in the latter, but was greater soy-fed pigs.

Cholesterol transport and uptake in miniature swine fed vegetable and animal fats and proteins. 1. Plasma lipoproteins and LDL clearance

In a 2 X 2 factorial arrangement, miniature pigs were fed four diets containing vegetable protein/fat (soybean) and animal protein (egg white)/fat (beef tallow) to demonstrate the effects of protein and fat source on total plasma cholesterol, lipoprotein distribution, low density lipoprotein (LDL) composition, and plasma clearance of LDL-cholesterol and protein. Beef tallow consumption resulted in greater plasma cholesterol concentration, decreased LDL-cholesterol concentration, and a lower LDL-cholesterol to LDL-protein ratio than did consumption of soybean oil. High density lipoprotein (HDL)-cholesterol concentration was increased by beef tallow consumption. Cholesterol percentage by weight in LDL was significantly greater in pigs consuming soybean oil than those consuming beef tallow. Percentages by weight of protein, triglyceride and phospholipid in LDL were not significantly different in any group. Dietary protein source had no significant effect on total plasma cholesterol concentration, lipoprotein concentration or LDL composition. Egg white consumption decreased fractional catabolic rate and irreversible loss of LDL-cholesterol and LDL-protein when compared with consumption of soy protein. Dietary fat source had no consistent effect on LDL clearance from plasma. Dietary fat and protein seemed to influence lipoprotein metabolism by different mechanisms. Fat source altered lipoprotein concentration and LDL composition, whereas protein source affected the removal rate of LDL from plasma.

Cholesterol transport and uptake in miniature swine fed vegetable and animal fats and proteins. 2. LDL uptake and cholesterol distribution in tissues

In a 2 X 2 factorial arrangement, miniature pigs were fed four diets containing vegetable protein/fat (soybean) and animal protein (egg white)/fat (beef tallow) to demonstrate the effects of protein and fat source on tissue cholesterol concentrations, uptake of intact low density lipoproteins (LDL) and free cholesterol exchange from LDL to tissues. Soybean oil feeding, compared with beef tallow feeding, resulted in greater concentrations of cholesterol in aorta, heart, and large and small intestines. Similar trends were seen in liver, adipose tissue and skeletal muscle. Dietary protein source had little or no effect on tissue cholesterol concentrations. Uptake of intact LDL, as measured by using [14C]sucrose-LDL, tended to be greater in pigs fed soybean oil or soy protein. Net exchange of free cholesterol from LDL, as measured with [3H]cholesterol, tended to be greater when vegetable products were fed. Relative contributions of whole tissues to total uptake by either mechanism were not influenced by diet. Mechanisms in addition to uptake of cholesterol from LDL seem to be involved in the greater accumulation of tissue cholesterol resulting from polyunsaturated fat feeding.

Effects of beef, soy and conventional diets on body composition and plasma lipids of young pigs fed restricted or liberal amounts of diet

Effects were determined of restricted and liberal feeding of beef-based, soy-based and conventional diets on growth rate, nutrient absorption, body composition and plasma lipid and urea concentrations of young pigs. Beef and soy diets contained more fat (40-50% of calories vs. 8-9%) and cholesterol (0.09 vs. 0%) than did conventional diets; calorie and protein intakes were equal across diets. Beef-fed pigs had greater average daily gain and absorption of fat and gross energy than did conventionally fed pigs; soy-fed pigs had intermediate growth rates but the greatest absorption of fat and gross energy. With restricted intakes, percentage of body fat was greater in soy-fed pigs than in pigs fed a conventional diet or beef and with liberal feeding, greater in soy- and beef-fed pigs than in pigs provided with a conventional diet. Plasma free fatty acid, triglyceride and cholesterol concentrations were greater in soy- and beef-fed pigs than in conventionally fed pigs. These results indicate that absorption and subsequent partitioning of nutrients toward body fat are influenced by composition as well as the amount of diet consumed. Our results also demonstrate that the pig can successfully be fed diets resembling human diets (i.e., high fat) and because of its physiological similarities to humans our understanding of nutrition and lipid metabolism of humans may be advanced.