224 BOARD OF AGRICULTURE. [Jan. 



know, — viz., that the propoyiion of these elements is im- 

 portant ; for this has an especial bearing upon what I shall 

 say of feeding animals. You know that you must supply to 

 a soil, at the outset infertile, nitrogen, potash and phosphoric 

 acid, and each in proper amount and proportion, to get a 

 profitable crop. An excess of solul)le nitrogen applied is 

 wasted ; for the crop does not need it, and the soil probably 

 cannot hold it for the crop of another year. 



The principles underlying the feeding of animals are 

 similar. Various as are the organs and substances of the 

 animal body, nearly all are made up of compounds which 

 may be referred to one of four classes ; viz., water, proteine 

 (nitrogen-containing substances), fat (carbon-containing 

 substances) and ash (phosphate of lime, etc.). These sub- 

 stances are either derived directly from the food or drink, or 

 are produced from their constituents as a result of changes 

 which take place in the body. At the expense of the food, 

 also, the animal heat is maintained and th^ force for all 

 work is generated. Some of the constituents of the food, 

 such as starch or fat, must be burned in the body to main- 

 tain its temperature. For every stroke of work, whether of 

 the heart, the stomach, lungs or legs, some compound of the 

 food or body must be broken up. These substances burned 

 or destroyed to produce warmth and work, however, fortu- 

 nately for the simplicity of our subject, are still of one of 

 two classes already mentioned, viz., proteine (albuminoids) 

 or fat; or they may belong to a third class, represented by 

 starch and sugar, and known as car])ohydrates. 



Now, two of the classes of substances mentioned as found 

 in the body we may disregard in considering methods of 

 feeding. These are water and ash : water because it costs 

 nothing, and the animal's appetite is a guide as to quantity ; 

 and ash because any ordinary animal food which supplies 

 enough proteine, fat and carl^ohyd rates will contain mineral 

 elements (ash) enough. We have not to think of them any 

 more than in feeding plants we have to think of supplying 

 iron or hydrogen. With respect to water, I must add that 

 the proportion in the food is far from being unimportant. 

 A food otherwise suitable may give poor results l)ecause too 

 watery. Whey fed exclusively to pigs would be an example. 



