58 Feeds and Feeding. 



81. Fat from carbohydrates. — Scientists agree that the fat in the 

 body of animals can be formed from carbohydrates. As early as 

 1842 Liebig maintained that animal fat was formed mainly from 

 the carbohydrates, tho it might also originate from the protein of 

 the food. The extensive experiments of Lawes and Gilbert of the 

 Rothamsted Station/ conducted from 1848-1853 with more than 

 400 animals, clearly showed that much more fat was stored than 

 could be derived from the fatty matter and protein of the food. 



Soxhlet- fed 2 full-grown pigs a daily ration of 4.4 lbs, of rice 

 meal for 5 days. One pig was then killed and its body analyzed, 

 while the other was fed 4.4 lbs. of rice, daily, and later a ration of 

 3.3 lbs. of rice with some meat extract, both foods which are almost 

 free from fat. After 82 days this pig was also killed and its body 

 analyzed. Assuming that the bodies of both pigs were of similar 

 composition when the first was killed, Soxhlet found the quantity 

 of fat formed in the body of the second pig and its source to be as 

 follows : 



Grams 



Maximum fat possible from fat in food __ 340 



Maximum fat possible from protein in food 2,488 



Maximum fat tliat must have been formed from carboliy- 



drates in food 19,352 



Total fat from 3 sources 22,180 



It is shown that during the trial 22,180 grams of fat were formed. 

 Deducting from this the sum of the maximum amounts of fat which 

 could have been derived from the fat and the protein supplied in 

 the food, there remains 19,352 grams of fat as the minimum which 

 must have been formed from the carbohydrates in the food. Hence 

 at least 87 per ct. of the fat formed by this pig during the trial 

 was derived from the carbohydrates in the food. 



The formation of fat by ruminants from the carbohydrates was 

 first demonstrated by Kiihn"' with the aid of a respiration appara- 

 tus. Oxen were fed for long periods on meadow hay and starch, 

 which provided a ration low in protein and fat. Kiihn shows that 

 even if all the carbon resulting from the digestion of the protein 

 and fat in the food went to form fat in the body, there still re- 

 mained a large amount of deposited fat which could only have 

 come from the carbohydrates of the food. These conclusions are 

 confirmed by later experiments by Kellner,* also with oxen. In 



' .Tour. Roy. Agr. See. VI, Ft. 1, 1895; Bui. 22, Office of Expt. Sta. 



- .Tahresber. Agr.Chem., 1881, p. 434, 



'■'• T.andw. Vers. Stat., 44, 1894, pp. 1-581. 



' Land. Vers. Stat., 53, 1900, pp. 1-450. 



