3. A7i idle animal needs less food than one which is hard at 

 work. — A locomotive does not require nearly as much fuel to keep 

 up steam when it is running " light," as when drawing a freight 

 train on an up grade. The little driving mare which stands in your 

 barn most of the time must have some food to renew the energy 

 used up in breathing, pumping blood throughout its body and other 

 wastes ; but the big team horse which has to pull the plow all day 

 or sled logs out of the swamp must have much better fare. 



4. It is as imich tax on a cow to give a hig yield of milk as it is 

 on a horse to do a hig daxfs work. — There are other ways of using 

 up energy than by physical exertion. Probably each of John's 

 cows spent as nnich energy in producing thirty pounds of milk a 

 day as a big Percheron horse does in a heavy day's work before the 

 plow. The food David gave his cows cost enough, and there was 

 enough of it ; but it was not the right kind to repair the waste 

 made in producing milk. Probably he did not know much about 

 the philosophy of milk production. That is the reason why he 

 failed. 



The cows which John bought of David soon began to pick up 

 under the new fare, and to give more milk. When David found 

 his cows were not paying him, he ought not to have been above 

 seeking advice from a more successful man like John. Or if he 

 had several cows and many kinds of feed-stuffs, he might have 

 changed rations till he had hit upon some combination of foods 

 which gave better results. But neither David nor any other farmer 

 has time for much of such work. It must be done by the Experi- 

 ment Station. The way we can best help the Davids of this State 

 is to tell them what they should aim to supply in their animal 

 rations, and the reasons for this selection. Then each man can pick 

 out for himself the various materials which answer his needs, and 

 which may be obtained to best advantage in his section. 



5. Many kinds of food are required. — We can be sure of this by 

 studying the composition of the animal body ; also by reflecting on 

 the many kinds of work which an animal does. The body of an 

 animal is made mostly of water, mineral matter, nitrogenous matter, 

 and fat. 



539 



