THE FEEDING AND MANAGEMENT OF CATTLE. 443 



Ether extract. On another sample of the fodder the chemist places 

 ether, which dissolves out whatever fats and wax it contains, and this 

 dissolved portion is called the ether extract or crude fat. Hay and 

 straw contain very little fat, and still less is found in mangolds or 

 turnips, while corn contains considerable, and oil meal and cotton-seed 

 meal a relatively large amount. 



Xitrogen-free extract signifies what is left of the organic matter of the 

 plant after deducting the preceding groups of elements. It contains 

 starch, sugar, dextrine, and gums. 



Carbohydrates. The nitrogen-free extract and the crude fiber are 

 grouped together under the term carbohydrates. The leading function 

 of the carbohydrates is to furnish fuel for the animal body. Portions 

 not needed for immediate wants may be converted into fat and stored 

 up in the tissues awaiting future demands. 



The figures given in all the columns of the table we have passed over 

 are derived from analysis in the laboratory, and represent the total 

 amount of each of the plant constituents in the several groups. Thus 

 far the investigation is purely a chemical one, though the grouping of 

 the substances has some relation to the uses of the food in the animal 

 system. Having learned the amount of each of the constituents in a 

 given fodder, the chemist proceeds to feed it to some farm animal, 

 usually an ox or a sheep, in order to ascertain what portion of each is 

 digestible. The value of gold ore is not rated by the total amount of 

 gold contained, but rather by that portion which can be recovered by 

 practical processes; so with our feeds, only those portions which can be 

 digested and utilized by the animal are really valuable. The results of 

 digestion trials are grouped in the last columns of the table under the 

 head ' Per cent of digestible matter," and these data have cost the 

 chemist and animal physiologist much patient labor; oven now the 

 results are crude and far from satisfactory. 



Let us study this table item by item, as we did the first part. We 

 learn that while the total crude protein in pasture grass is 4 in 100 

 pounds, the digestible crude protein is 2.8 pounds in a hundredweight. 

 The digestible carbohydrates, the eomi>oumls of crude fiber and nitrogen- 

 free extract are 12.3 pounds, and the digestible ether extract O.G pound. 

 The chemist has found that a pound of fat will give about 2.2 times as 

 much heat as a pound of carbohydrates. Since the fats serve the same 

 purpose in the Ixwly as the carbohydrates, we cau reduce the fat found 

 in a fodder to a carbohydrate equivalent by multiplying it by 2.2. To 

 obtain the nutritive ratio expressed in the last column of the table, the 

 digestible fat is multiplied by 2.2 and added to the digestible carbo- 

 hydrates, and the sum divided by the digestible protein. Tin- nutritive 

 ratio of pasture grass is 1 : 4.9; that is, for every pound of digestible 

 protein in pasture grass there an? 4.9 pounds of digestible carbohydrates 

 and carbohydrate equivalents. The following table snminarix.es the 

 results of analyses in digestion trials unjust explained: 



