SOURCES OF FAT IN ANIMAL BODY 537 



Table 2 



The Effect of the Amount of Cottonseed Oil in the Diet 



on the Back Fats of Hogs Receiving a Basal Diet of Hominy" 



Groups receiving basal diet plus 



Group 4% 8% 12% 



Category basal diet oil oil oil 



Average refractive index (40°C. ) . 1 . 4591 1 . 4595 1 . 4599 1 . 4609 



Iodine number 60.6 60.5 64.4 77.4 



Saponification number 196.2 197.9 197.6 195.2 



Melting point, °C 41.7 45.7 46.3 40.9 



Saturated acids: 



Total, % 39.0 45.5 44.0 39.6 



Myristic, % 1.6 1.1 0.8 1.0 



Palmitic, % 24.3 24.1 20.9 13.2 



Stearic, % 13.0 20.3 22.3 25.3 



Unsaturated acids : 



Total, % 56.4 50.9 53.6 55.8 



Oleic, % 47.9 38.2 34.2 30.4 



Linoleic, % 8.5 12.7 17.4 25.4 



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

 398 (1931), pp. 392-393. 



compared to a value of approximately 2 : 1 in the hogs on the several diets 

 other than cottonseed oil. Hilditch 100 likewise reported that palmitic acid 

 is a more important saturated acid in beef tallow than is stearic acid, 

 although in mutton tallow a reverse relationship obtains. The importance 

 of palmitic acid in the fat of rats has also been noted by Banks et al. m 



(d) The Hardening Effect of Carbohydrates. It has long been known 

 that much of the body fat deposited under normal conditions is derived 

 from carbohydrate (see page 538). As the results of Ellis and Isbell 92 

 demonstrated, fat from hogs on a low-fat diet tends to be hard and to have 

 an iodine value approximating 60. Ellis 95 has shown that, when a low- 

 fat diet (corn) was substituted for a peanut ration, a marked alteration in 

 the type of adipose tissue ensued. The fat changed from the "soft" type 

 to the "hard" type, coincident with a reduction of the linoleic acid content 

 from 23 to 9%. This was reflected in the change of the iodine number, 

 which decreased from 93 to 63 during the corn diet. Saturated acids in- 

 creased from 19 to 33% during the hardening period. Anderson and 

 Mendel 49 reported a similar result in the rat. After the deposition of the 

 "soft" fat in this species, the fat in the diet was replaced equicalorically by 

 corn starch. A progressive "hardening" of the fat resulted over the period 



100 T. P. Hilditch, /. Soc. Chem. Ind., 54, 139-145, 163-167, 184-189 (1935). 



101 A. Banks, T. P. Hilditch, and E. C. Jones, Biochem. J., 27, 1375-1382 (1933). 



