POOD OF PBODUCTION. 347 



feeder; that is, what part of a full ration is really used for 

 production or profit? We greatly need accurate and 

 thorough experiments to determine this to an approximate 

 fraction. There are many cases that throw light upon it. 

 The German experimenters have undertaken to lay down 

 the rule that 2 per cent, of the live weight of cattle of the 

 dry substance of meadow hay is required as a daily ration, 

 of support, without gain. If this rule is taken, then, as 

 Mr. HorsfalPs six cows averaged 1,078 Ibs., it would require 

 21.74 Ibs. of dry substance for the food of support. The 

 averaged amount of dry substance eaten by each cow per 

 day was 31.11 Ibs., as appears by the table given on a pre- 

 vious page. This would be nearly .7 (seven-tenths) required 

 as the food of support, and a little over .3 (three-tenths) as 

 the food of production; and yet these cows yielded 35 Ibs. 

 of milk per day, besides increasing in weight. This must 

 be considered as a remarkable result. We have usually 

 estimated two-thirds of a full ration as required for the 

 food of support, and this rather more than sustains that 

 estimate. Let us see if we can find the elements in K of 

 the ration given by Mr. Horsfall to produce the 35 Ibs. 

 of milk, or 40,512 Ibs. in 191 days, besides a gain in the 

 weight of the cows of 500 Ibs. Mr. H. supposed that this 

 gain in weight was composed of 300 Ibs. of fat and 200 Ibs. 

 of lean flesh. This would give only 46 Ibs. of dry flesh, or 

 fibrin, and about 270 Ibs. of solid fat. The 40,512 Ibs. of 

 milk would contain the following substances: 



Casein (albuminoid) 1,815 Ibs. 



Fat or butter 1,276 " 



Milk sugar 1,932 " 



Mineral matter (ash) 243 " 



Water, 87 per cent, 35,246 " 



40,512 



If we add the fat and fibrin of 500 Ibs. gain, it will 

 stand 



Casein and fibrin 1,861 Ibs. 



Fat and butter 1,446 " 



Milk sugar 1,932 " 



