I. AGRICULTURE AND RURAL ECONOMY. 337 



from 100 pounds to 200 pounds in seventeen weeks. He 

 then points out that if, instead of allowing the pig to have as 

 much barley meal as he will eat, the 500 pounds of meal had 

 been made to last many more weeks, the result would have 

 been that the animal would have appropriated a correspond- 

 ingly larger proportion of the food for the purposes of respi- 

 ration and perspiration, and a correspondingly less propor- 

 tion in the production of increase. In other words, if the 500 

 pounds of barley meal were distributed over a longer period 

 of time, it would give less increase in live weight, and a lar- 

 ger proportion of it would be employed in the mere mainte- 

 nance of the life of the animal. Indeed, if the period of con- 

 sumption of the 500 pounds of meal be sufficiently extended, 

 the result will be that no increase whatever will be produced, 

 and that the whole of the food, excepting the portion ob- 

 tained as manure, will be expended in sustaining the animal's 

 existence. 16 A, July, 1870, 377. 



EFFECT OF THE FOOD OF COWS ON THE COMPOSITION OF 



THE MILK. 



A series of experiments prosecuted not long since in Ger- 

 many led to the conclusion that, contrary to the usual im- 

 pression on the subject, very considerable changes in the 

 composition of food may be made without inducing corre- 

 sponding changes in the relative constituents of the milk of 

 the cow, the only effect being in the amount of the concen- 

 tration of the milk. To determine these results with accu- 

 racy, Dr. Kuhn has repeated the experiments, with the gen- 

 eral result of showing that an increase in the albumen and 

 fatty elements of a moderate diet produces an increase in the 

 milky yield, which gradually rises (along with bodily condi- 

 tion) to a certain maximum, corresponding in each case with 

 the maximum increase of the above elements. Sooner or 

 later, however, the natural diminution depending on the du- 

 ration of lactation occurs, and no increase can be produced 

 by increasing the food. Diminution of the above elements 

 of the food causes a diminution in the milk yield. The addi- 

 tion of fat increases the ingredients of milk generally, and 

 has no special influence on the amount of fat in the milk. 

 The absolute production of the individual elements of the 

 milk agrees generally with the relative production of the 



P 



