344 



Composition of Animal Food. 



[June 21, 



analysed ; as the actual weights and condition of animals coming under 

 similar designations may vary considerably. 



It was of more interest to consider the amounts of the mineral 

 constituents in carcass parts, in offal parts, and in all parts, per 1,000 lbs. 

 fasted live-weight, of each description of animal. 



It was shown that a given live-weight of oxen carried off much 

 more mineral matter than the same weight of sheep, and a given 

 weight of sheep much more than the same weight of pigs. With 

 each description of animal the amounts of phosphoric acid, lime, and 

 magnesia, are less in a given live-weight of the fatter than of the 

 comparable leaner individuals. Of both potash and soda, again, the 

 quantity is less in a given live-weight of the fatter animals. The 

 same may be said of the sulphuric acid and the chlorine ; in fact, in 

 a greater or less degree, of every one of the mineral constituents. 



It was estimated that the loss to the farm of mineral constituents 

 by the production and sale of mere fattening increase was very small. 

 It was greater of course in the case of growing than of only fatten- 

 ing animals. In illustration, the amounts of some of the most impor- 

 tant mineral constituents removed annually from an acre of fair 

 average pasture and arable land in various products were compared. 

 Such estimates could obviously be only approximate, and the quantities 

 will vary considerably. With this reservation, it may be stated that,, 

 of phosphoric acid, an acre would lose more in milk, and four or five 

 times as much in wheat or barley grain, or in hay, as in the fattening 

 increase of oxen or sheep. Of lime, the land would lose about twice 

 as much in the animal increase as in milk, or in wheat or barley 

 grain ; but perhaps not more than one- tenth as much as in hay. Of 

 potash, again, an acre would yield only a fraction of a pound in 

 animal increase, six or eight times as much in milk, twenty or thirty 

 times as much in wheat or barley grain, and more than 100 times as 

 much in hay. 



From the point of view of the physiologist, it would doubtless have 

 been desirable that the selection of parts for the preparation and 

 analysis of the ash should have been different, and more detailed. 

 The agricultural aspects of the subject had, however, necessarily 

 influenced the course of the inquiry ; and the extent of the essential 

 work had enforced the limitation which had been adopted. The 

 results must be accepted as a substantial contribution to the chemical 

 statistics of the feeding of the animals of the farm for human food. 



