334 IOWA DEPARTMENT OF AGRICULTURE 



the vegetable fats and oils or in the animal fats with the exception 

 of the fats of the glandular organs (liver fat and fat of kidneys). 

 The specific action of vitamines in the diet of growing animals is 

 apparent in the following conclusions reached as a result of some 

 of the investigations of McCollum, Hart and others, at tlie Uni- 

 versity of Wisconsin : 



"If we take such a mixture of food stuffs which do not allow an animal 

 to grow and stir into it a small quantity of egg yolk, say for a pound of 

 the ration an ounce of egg yolk, growth can be induced. The same result 

 would be obtained if we had put in an ounce of evaporated milk instead of 

 the egg yolk. Suppose next that we take all the fat out of this satisfactory 

 ration by extracting it with something that dissolves fats. It will be 

 found that though the ration will be able to maintain young rats without 

 any increase in weight for about a month, it will no longer be able to 

 induce growth. Only on restoring the extracted fats to the ration will 

 growth be made. A similar result could have been obtained by adding 

 butterfat or fats obtained from certain animal organs; but other fats 

 such as lard, almond oil and cottonseed oil would not have brought about 

 the same result. 



"These facts might well cause us to stop and think. Because of the 

 fact that some fats naturally contain substances necessary for growth 

 while other fats do not contain such substances, there has arisen the 

 necessity of speaking of the presence or absence of a fat soluble vita- 

 mine. This vitamine is closely, though not exclusively, associated with 

 fats. It is also found in seeds to a certain extent, and the leafy portion 

 of plants to a considerable extent also contains this substance. Milk, 

 eggs, and alfalfa leaves are a very good source of this unknown con- 

 stituent, although there is every reason to suppose that forage plants in 

 general are a better source of this class of vitamines than the grains. 



"The fact that the fat soluble vitamine of milk is concentrated in the 

 fat of this product might lead to the inference that skim milk would be 

 inadequately provided with this substance. It is evident, however, that 

 a portion of the vitamine contained in the milk fats dissolves in the whey 

 of milk and consequently is present even in skimmilk, although perhaps 

 not as abundantly as we should wish. 



"Of late there has appeared in the advertising literaure of manufac- 

 turers of milk-product substitutes the statement that the vitamines of 

 milk are destroyed by pasteurization. This statement is absolutely false. 

 In our experiments in the study of the vitamines, butterfat is heated 

 higher than is required for pasteurization and for much longer periods 

 of lime without destroying this substance. 



"Further, there is in these times of food scarcity a tendency to use 

 plant oils as substitutes for butterfat, even claiming for them a value 

 equal to that of butterfat. No plant oils so far investigated, and those 

 include cottonseed oil, almond oil, peanut oil, cocoanut oil, and sun- 

 flower seed oil, contain the fat soluble vitamine in appreciable quanti- 

 ties. It is false to claim these as substitutes for butterfat. We do not 

 condemn them, for they are valuable food products as sources of energy 



