918 XIV. NUTRITIONAL VALUE OF FATS 



because of the relatively high vitamin E content of vegetal^le oils as con- 

 trasted with that of butterfat, it is difficult to explain the recent findings of 

 Viswanatha et al,^^'' who reported that butterfat provided better growth 

 for rats on a lactose or sucrose diet than did corn oil, e"\'en when the latter 

 diet was supplemented with vitamin E. 



(c) Multigeneration Tests as a Method for Comparing the Nutritional 

 Value of Animal and of Vegetable Fats. The so-called "multigeneration" 

 method was employed by several investigators as a criterion of the nutri- 

 tional value of foodstuffs. In this procedure, the rats are raised on a diet 

 containing the test substances until mature; they are then bred, and the 

 progenies are continued on the same diet. After the young are weaned, the 

 parents are discarded and the new generation is bred at maturity. '^^ 

 Sherman and Campbell'*''^'^-^^ devised a simple diet which has been employed 

 successfully in carrying out multigeneration experiments with diets con- 

 taining butterfat as the sole source of fat. This experiment has progressed 

 further than any other similar type of experiment on record. The diet w^as 

 successful in enabling rats to continue growth, reproduction, and lactation 

 for at least sixty -seven generations; when last reported (1949) it was still 

 in progress. ^^' In the 1949 report the authors stated that the adequate 

 vitamin A intake for a laboratory rat family of the sixty-seventh genera- 

 tion was 3 I.U./g. dry food. The so-called Sherman B diet, which has been 

 used from the fortieth generation on in their tests, contains one-third whole 

 milk powder, and two-thirds ground wheat berries to which 2% of sodium 

 chloride is added. A test similar to that of Sherman was instituted in the 

 author's laboratory in 1940. In the 1945 test, skim milk powder was em- 

 ployed in place of whole milk powder, and an amount of vitamin A-fortified 

 vegetable margarine fat comparable to that of the butterfat present in the 

 whole milk powder was added to the skim milk powder. At the end of ten 

 generations of this series of tests, the rate of growth of both males and 

 females had reached a plateau considerably higher than at the start of the 

 test.'^^ Fertility and lactation, also, had been maintained at a high level 

 throughout the first ten generations. The results after twenty-five genera- 

 tions mirrored the early tests in all respects. ^^' In the twenty-fifth genera- 



"' T. Viswanatha, J. E. Gander, and I. E. Liener, J. Nutrition, 52, 613-626 (1954). 



"8 H. J. Deuel, Jr., S. M. Greenberg, C. E. Calbert, R. Baker, and H. R. Fisher, Food 

 Research, 16, 258-280 (1951). 



"» H. C. Sherman and H. L. Campbell, /. Biol. Chem., 60, 5-15 (1924). 



3M H. C. Sherman and H. L. Campbell, /. Nutrition, 2, 415-417 (1929-1930). 



«' H. C. Sherman and H. Y. Trupp, Proc. Nat. Acad. Sci., 35, 90-92 (1949). 



3«« H. J. Deuel, Jr., L. F. Hallman, and E. Movitt, J. Nutrition, 29, 309-318 (1945) 



^' H. J. Deuel, Jr., S. M. Greenberg, E. E. Savage, and L. Bavetta, J. Nutrition, /,2, 

 239-255(1950). 



