NORMAL FACTORS ALTERING DIGESTIBILITY OF FATS 



233 



The most marked effect was noted for peanut oil; the gain in weight/ 1000 

 Cal. decreased from 87 for the unheated oil to 30 for the oil heated for 

 thirty hours. Treatment of herring oil at 275°C. for only ten hours re- 

 duced this efficiency index from 64 to 28. When linseed oil previously 

 heated for twelve hours was added to the diet at a 20% level, the index 

 dropped from 80 to 4. On the basis of later work from this same labora- 

 tory, 106 it was concluded that the primary cause of the reduction in nutri- 

 tive value of the diets which contained the thermally polymerized linseed 



5 10 15 20 25 30 



DEGREE OF POLYMERIZATION IN PERCENT 

 Fig. 2. The relationship between the degree of polymerization in % and the co- 

 efficient of digestibility of sardine oil. 104 The amount of polymerization was cal- 

 culated by the following formula: 



Iodine No. unpolymerized oil — Iodine No. polymerized oil 

 Iodine No. unpolymerized oil 



X 100 



oil was the presence of one or more dimeric fatty acid radicals; these are 

 believed to act in some way inimical to the well-being of the animals. 

 Crampton et al. 107 later suggested that the destruction of some of the es- 

 sential fatty acids, which occurs during polymerization, may act to aggra- 



108 E. W. Crampton, R. H. Common, F. A. Farmer, F. M. Berryhill, and I. Wiseblatt 

 J. Nutrition, U, 177-189 (1951). 



107 E. W. Crampton, R. H. Common, F. A. Farmer, A. F. Wells, and D. Crawford, 

 J. Nutrition, 49, 333-346 (1953). 



