THE PROCESS OF DIGESTION 81 



the energy produced. By means of the calorimeter, one 

 measures the heat or energy used in labor, or thrown off from 

 the body, or passed off as breath through the mouth. The 

 application of this knowledge will be found in the next 

 chapter. At the Pennsylvania and New Hampshire Experi- 

 ment Stations there are respiration calorimeters made to 

 hold the larger animals. In these there have been con- 

 ducted very interesting experiments on the energy value 

 of foods as fed to cattle under different conditions. 



The palatability, or taste, of food is regarded very im- 

 portant in feeding animals. If the food is pleasing to the 

 taste, the animal will digest it better, because the fluids used 

 in digestion will flow more freely, and thus act more com- 

 pletely on the food. Nice sweet hay is greatly relished, while 

 that which is somewhat mouldy, or has not been properly 

 ripened, or cured, will be poorly eaten or entirely refused. 

 The animal that feeds best has a good appetite, and eats 

 plentifully. A great Russian physiologist named Pawlow, who 

 conducted extensive experiments relating to the effects of the 

 appetite on the forming of the digestive fluids in dogs, learned 

 that digestion, appetite, and palatability all go together. 



The use of water by the animal is very important. 

 Water may keep the entire body in a healthy condition. 

 The digestive fluids and blood need given amounts of water 

 to do their work right, and water is needed to keep the intes- 

 tines open and active, and to regulate body temperature. 

 Experiments have shown that farm animals need a certain 

 amount of water for every pound of dry matter eaten. For 

 example, a horse or sheep needs from two to three pounds of 

 water for each pound of dry matter consumed. With some 

 foods more water is required than with others. The cow 

 that eats corn silage will drink but little water compared 

 with the one fed the dried plant or corn stover. 



The nutritive ratio is frequently referred to in discussing 

 the use of rations in practical feeding. This term is used to 



