442 



PRINCIPLES OF AGRICULTURAL CHEMISTRY 



those kept in warmer surroundings. A pig kept in a pen at 

 freezing temperature had a softer fat than similar pig kept in a 

 pen at 30-35 C. 



Composition of Gain of Weight in Fattening. The composition 

 of the increased weight in fattening has been studied in two ways : 



First, animals of different degrees of fatness, but otherwise 

 comparable, were killed and subjected to analysis. 



Second, animals raised alike were selected, and some killed at 

 the beginning, others at intermediate stages, others at the end of 

 the fattening experiment. The bodies were subjected to analysis. 



The animals killed at the end of the experiment or during the 

 process, were supposed to have originally had the same composi- 

 tion as those killed at the beginning of the experiment. When 

 the live weight of the animals and their percentage composition is 

 known, it is a simple matter to calculate the composition of gain 

 in material during fattening. 



The composition of sheep at different degrees of fatness was 

 found at Rothamsted 1 to be as follows : 



PERCENTAGE COMPOSITION OF SHEEP. 



It is noted that there is a decided decrease in the percentage of 

 water, a slight decrease in the percentage of proteids, and a large 

 increase in the percentage of fat, during the process of the fatten- 

 ing. With other animals than sheep, the results were similar. 



The following table shows one calculation of the composition 

 of the gain in fattening, and illustrates the method of procedure. 

 The part of the offal in the gain is calculated also. 

 1 Bulletin 22, p. 249, Office Exp. Sta., U. S. Dept. Agr. 



