48 PRINCIPLES OF FEEDING FARM ANIMALS 



fattening of farm animals. Careful experiments have thus shown 

 that over four-fifths of the fat formed in the body of pigs must at 

 times have had its origin in other sources than the protein and fat 

 of the food, and could, therefore, only have come from the carbo- 

 hydrates. It is of interest to note that the feeds generally employed 

 in the fattening of farm animals are all of a starchy character, like 

 Indian corn and other cereals, mill feeds, etc., containing in most 

 cases between 70 to 80 per cent of carbohydrates. 



Milk Fat from Carbohydrates. Experiments with milch cows 

 by Jordan furnish striking evidence that milk fat can be formed 

 on practically fat-free rations. 3 In one experiment a milch cow 

 that had been fresh four months was fed a ration consisting of 

 hay, corn meal and ground oats, for ninety -five days, the fat in the 

 feeds having been previously extracted with naphtha by the method 

 employed in the manufacture of new-process linseed meal. Her 

 feed contained during -this period 11.6 pounds of fat, of which 5.7 

 pounds was digested; she produced 62.9 pounds of fat in her milk, 

 and in addition gained 47 pounds in body weight during the trial. 

 Not over 17 pounds of the fat in the milk could have been produced 

 from the protein supply in the feed (see below), showing that about 

 40 pounds of the fat must have come from the carbohydrates in 

 the feed. 



Body Fat from Carbohydrates. Experiments conducted by 

 European scientists have likewise demonstrated that carbohydrates 

 can form body fat in case of fattening steers -and pigs. This was 

 first shown in respiration experiments with fattening steers con- 

 ducted by Kuehn and later by Kellner. The trials showed that 

 after the fat formed from the digested protein and fat in the feed 

 was accounted for, there was still a large amount of body fat that 

 could only have come from the carbohydrates of the feed. By 

 adding carbohydrate materials to -a basal ration, the effect of which 

 was determined, Kellner found that one pound of digestible com- 

 ponents was capable of producing the following amounts of fat in 

 the body of mature -steers : 



1 pound digestible starch 248 pound fat 



1 pound cane sugar 188 pound fat 



1 pound digestible fiber 253 pound fat 



The lower efficiency of cane sugar for fat formation may be ex- 

 plained by the fact that this substance is easily soluble and, there- 

 fore, more readily decomposed by the bacteria in the intestines 

 than starch or fiber. By similar experimentation, one pound of 

 digestible protein has been found capable of producing .235 pound 



3 Geneva (N. Y.) Station, Bulletins 132 and 197. 



