CHAPTEE XIV. 

 FOODS AND FEEDING. 



MANY references have already been made to the chief constituents of 

 the food of animals. In this chapter will be given a summary of some 

 of the chief facts relating to the composition, digestibility and other 

 properties of foods and to the principles upon which the construction 

 of rations for farm animals, under various circumstances, is based. 



The Composition of Foods. In addition to the crops grown on 

 the farm, the compositions of which have already been discussed in 

 Chapter XII, many purchased foods are used in feeding animals. 

 Many of these are bye-products, obtained either in the preparation of 

 flour, meal, etc., from grain of all sorts, or residues left after the ex- 

 pression or extraction of oil from oil-bearing seeds. 



The constituents of foods are usually divided into 



[Soluble carbohydrates 



., Crude fibre 



1. Non-mtrogenous 



^Mineral matter 

 1^.. ('Albuminoids or proteids 



(Amino-compounds and amides 



This plan of reporting analyses of foods, though unsatisfactory 

 in some respects, has been generally adopted and the great majority 

 of published analyses are expressed in its terms. 



The imperfections of the method, as regards carbohydrates, crude 

 fibre and albuminoids have already been alluded to in the chapters on 

 Crops and the Constituents of Plants. 



The composition of the usual farm crops has already been given 

 but it remains to briefly describe the chemical nature of certain bye- 

 products used as foodstuffs on the farm. 



Bye-products from Oil-bearing Seeds. Prominent among 

 these are the residues left after the expression or extraction of oil 

 from oil-bearing seeds. These are known under the general name 

 of " oil cakes," among which the more important are 



Linseed cake. The composition of linseed has already been given. 

 In the manufacture of linseed oil the crushed seed is treated by one 

 of two processes (1) simple pressure aided by heat, or (2) extraction 

 by means of petroleum naphtha. In the latter process, which is 



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