912 XIV. NUTRITIONAL VALUE OF FATS 



Henry et al.,^"- and Lassen and Bacon*^^ also reported that the growth- 

 promoting properties of ^'egetable oils and of butter were similar. One 

 explanation for the greater growth of the rats on the butterfat diets as com- 

 pared with those receiving diets containing other fats, as observed in the 

 experiments of Schantz et al.,-^^ might be that the rats ate more of the but- 

 ter-containing diet. Thus it was shown that rats preferred a diet with 

 artificial butter flavor (diacetyl) to a bland unfiavored one.^^* Parrish 

 et al}~^ observed that, although the a^'erage efficiency of conversion of the 

 food to bodj^ tissue over a period of six weeks was similar for rats receiving 

 a butterfat ration and for those fed corn oil, the average consumption of the 

 ration was greater on the butterfat diet. The gain in weight on cither 

 ration was related to the amount of food consumed. Although Boutwell 

 and co-workers^- ^ failed to demonstrate a sufficiently marked improvement 

 in the consumption of corn oil diets with the addition of diacetyl to produce 

 growth equal to that observed when butterfat was fed, there was an appre- 

 ciable increase in food consumption as a result of adding this flavoring. 

 According to Scott and Verney,''-'- however, young rats preferred diets 

 containing hydrogenated \-egetable oil rather than food including butterfat, 

 or corn or cottonseed oil. 



One criticism raised against the technic used in the original experiments 

 of Deuel and co-workers""^ was that the beneficial effects of the vegetable 

 fat diets may have resulted from butterfat present in the skim milk pow- 

 der,'-' since this contained 1.1% of residual fat. In order to answer this 

 criticism, tests were repeated in which the residual fat was previously re- 

 moved as completely as possible from the skim milk powder by the use of 

 a combined ethyl alcohol and diethyl ether extraction. Even under these 

 conditions, no difference could be observed in the rate of growth of weanling 

 rats during a twelve-week period on diets containing the extracted skim 

 milk powder, irrespective of Avhether a butterfat, a vegetable margarine, 

 or one of a number of vegetable oils was used in the diet.?-* 



b'. Experiments on Prematurely Weaned Rats: According to Boutwell 

 el al.^-° the need of the young rats for the specific fatty acids reputed to be 



"8 S. Lassen and E. K. Bacon, /. Nutrition, 39, 83-91 (1949). 



3" H. J. Deuel, Jr., and E. Movitt, /. Nutrition, 27, 339-346 (1944). 



320 D. B. Parrish, E. R. Shiner, and J. S. Hughes, J. Nutrition, 31, 321-331 (1946). 



32> R. K. Boutwell, R. V. Geyer, C. A. Elvehjem, and E. B. Hart, Proc. Sac. Expll. Biol. 

 yi/ed., 55, 153-155(1 944). 



3" E. M. Scott and ¥.. L. Verney, J. Nutrition, 36, 91-98 (1948). 



323 Anonymous, Nutrition Revs.', 2, 267-270 (1944). 



32* H. J. Deuel, Jr., C. Hendrick, E. Movitt, M. E. Crockett, I. M. Smyth, and R. J. 

 Winzler, J. Nutrition, 31, 747-753 (1946). 



32* R. K. Boutwell, R. P. Geyer, C. A. Elvehjem, and E. B. Hart, J. Dairy Sci., 26, 

 429-437(1943). 



