FATS AS ESSENTIAL DIETARY COMPONENTS 847 



free diets. ^""^^ In experiments carried out by Kummerow and co- 

 workers,^^ animals on a diet containing no essential fatty acids but in- 

 cluding 5% hydrogenated coconut oil did give birth to living young, but 

 these did not sur\d^'e more than se\'enty-two hours. The mothers and 

 young were deficient in arachidonic acid, and not in fat per se. However, 

 when the diet contained 5% corn oil, 85% of the young survived to wean- 

 ing. After the feeding of corn oil to the mothers the phospholipids of the 

 young contained five to ten times more arachidonic acid than did the 

 phospholipids of pups from rats on fat-free regimens. Although it is 

 obvious that marked differences would be expected to exist in the perform- 

 ance of rats during pregnancy and lactation when fat-free diets were 

 used, as contrasted with the results when fat-containing diets were em- 

 ployefl, it is somewhat more difficult to demonstrate variations in these 

 physiologic functions when ditferent IcatIs of dietary fat were fed. Thus 

 no differences in reproductive and lactation performance have been noted 

 in normal rats which received 5 to 40% of fat in the diet, but in all cases 

 the results were superior to those in rats which were fed a fat-free diet.^^ 

 However, Scheer and co-workers^* reported that, when animals were 

 first subjected to a twelve-weeks period of undernutrition followed by 

 an ad libitum feeding period, the best performance as far as both the 

 number in the litter and the total weaning weights were concerned, was 

 obtained in the group receiving 40% of cottonseed oil in the diet. Thus 

 the average litter weights of the rats, at weaning, from mothers on diets 

 containing different levels of cottonseed oil were as follows: 0% fat but 

 containing 1% linoleate, 152 g.; 5% fat, 219 g.; 10% fat, 167 g.; 20% 

 fat, 230 g. ; and 40% fat, 283 g. The average weight of the individual 

 weanhng rats approximated 30 g. in the four groups receiving fats. The 

 increased litter weights are a reflection of the larger litters which the rats 

 on the high-fat diets were able to bring to weaning. In another group of 

 tests of Scheer and co-workers,'^ a studj^ was made of the fertility of ani- 

 mals which had been subjected to severe caloric restriction to such a de- 

 gi-ee that thcN^ had lost approximately half of their body weight over a 

 twelve-weeks period; this period of undernutrition was followed by an 



30 H. M. Evans, S. Lepkovskv, and E. A. Murphv, /. Biol. Chem., 106, 431-440 

 (1934). 



31 E. C. Maeder, Anat. Record, 70, 73-88 (1937). 



'2 F. W. Quackenbush, F. A. Kummerow, and H. Steenbock, J. Nutrition, 24, 213-224 

 (1942). 



" H. J. Deuel, Jr., C. R. Martin, and R. B. Alfin-Slater, /. Nutrition, 54, 193-199 

 (1954). 



^* F. A. Kummerow, H. P. Pan, and H. Hickman, /. Nutrition, 46, 489-498 (1952). 



