536 



VI. OCCURRENCE OF LIPIDS IN THE ANIMAL 



and those on 8% of cottonseed oil (saturated acids, 39.6%; linoleate, 

 27.3%). 



(b) The Hardening Effect of Cottonseed Oil. It has been beautifully 

 demonstrated by Ellis and Isbell 92 and by Ellis, Rothwell, and Pool 53 

 that cottonseed oil exerts a marked hardening effect on the storage fat of 

 the pig when fed at a 4% level in the diet. This is in contradistinction to 

 the behavior of corn, soybean, and peanut oils, which produce a definite 

 softening of the lard when administered at this level. Other workers 96 - 97 

 had also previously shown that the lard produced by hogs on a ration of 

 cottonseed meal was firm and had a high melting point, while a decreased 

 proportion of the volatile fatty acids was noted in butterfat after a cotton- 

 seed meal, or when cottonseed oil was present in the diet. 98 Table 1 

 illustrates the effects of the several types of dietary fat on the content of 

 unsaturated acids in the lard, while Table 2 shows the effect of progressively 

 increasing amounts of cottonseed oil on the composition of the lard, in 

 both saturated and unsaturated acids. 



Table 1 

 The Effect of the Vegetable Oil in the Diet on the Firmness and Composition 



of Lard" 



» Adapted from N. R. Ellis, C. S. Rothwell, and W. O. Pool, J. Biol. Chem., 92, 385- 

 398 (1931). 



(c) Factors Affecting the Ratio of Palmitic to Stearic Acid. In addition to 

 the variations in linoleic and oleic acids in hog fat as related to diet, the 

 relationship of palmitic to stearic acid is of considerable interest. Bhatta- 

 charya and Hilditch 99 have reported the analyses of a number of lards in 

 which the palmitic acid: stearic acid ratio varied from 3:1 to 1.5:1, as 



96 H. H. Harrington and D. Adriance, Texas Agric. Expt. Sta. (College Sta.), Bull. 

 No. 29, 347-355 (1893). 



97 C. L. Hare, J. Ind. Eng. Chem., 5, 410-414 (1913). 



98 C. H. Eckles and L. S. Palmer, Missouri Agric. Expt. Sta., Research Bull. No. 27, 

 3-44 (1916). 



99 R. Bhattacharya and T. P. Hilditch, Biochem. J., 25, 1954-1964 (1931). 



