272 BEGINNINGS IN ANIMAL HUSBANDRY 



intestines 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 silage will drink but little water compared with the 

 one fed dry corn fodder. 



The nutritive ratio is frequently referred to in discussing 

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

 express the ratio of the digestible protein to the digestible 

 non-protein substances in the food, or the combined car- 

 bohydrates and fat to the protein. In order to compare 

 these substances on an equal basis, they are reduced to the 

 same heat valuation. Protein and the carbohydrates do have 

 the same heat value, but a pound of fat is equivalent to 

 about 2J4 pounds of either one of these. Consequently the 

 chemist, in order to place them on an equal footing in heat 

 value, multiplies the digestible fat by 2J4- The nutritive 

 ratio is found by adding this to the amount of the carbo- 

 hydrates, and then dividing the sum by the digestible pro- 

 tein content. The following example will illustrate the 

 method of finding the nutritive ratio: 



Oats contain 10.7 pounds of digestible protein, 50.3 

 pounds carbohydrates, and 3.8 pounds fat. Then the ratio 

 is worked out in this manner. 3.8 pounds fat x 2% = 8.55 

 = the carbohydrate equivalent of the fat. 



50.3+8.55 =58.85 

 10.7 ) 58.85 ( 5.5 

 53.5 



535 

 535 



Nutriti^/e ratio, 1:5.5 



