Abstract
Ruminant and swine triglycerides have higher concentrations of stearic acid and lower concentrations of oleic acid than do triglycerides of other animals such as rats and chickens. Two new theories are herein advanced to explain this: (1) that ruminants and swine synthesize stearic acid de novo by fatty acid synthetase rather than palmitic acid which is the end product of fatty acid synthetase in rats and chickens, or (2) that ruminants and swine have a low rate of conversion of stearic acid to oleic acid (stearoyl desaturation) leading to an accumulation of stearic acid. Theory (1) was found to be incorrect as lauric, myristic, and palmitic acids were the major products of fatty acid synthesis from 1-C¹⁴-sodium acetate by homogenates of liver and adipose tissues of sheep and pigs. Since there was very little stearic acid synthesis the high content of this acid in the fats of these animals could not be the product of a high level of its de novo synthesis by fatty acid synthetase. On the other hand, when the stearoyl desaturase activities were assayed in homogenates of liver and adipose tissues of sheep, pigs, rats and laying hens it was found that in the livers of sheep fed a low fat diet and of pigs, rats, and hens fed fat-free diets the desaturase activities were 7, 18, 50, and 44%, corresponding to stearic acid concentrations of 28, 7, 2, and 6% in the respective triglycerides. The oleic acid concentrations were 26, 43, 37, and 54%, respectively. ...
Cook, Leonard James (1969). Factors which determine stearic and oleic acid concentrations in animal fats. Doctoral dissertation, Texas A&M University. Texas A&M University. Libraries. Available electronically from
https : / /hdl .handle .net /1969 .1 /DISSERTATIONS -173922.