SCIENTIFIC FARMING AT ROTHAMSTED. 



39* 



and voided as manure, are of the first importance, as these are the two 

 factors that determine the economy of feeding. The expenditure of 

 energy in the system, from the nitrogenous constituents of the food, is 

 not, therefore, included in the last column, as all of the nitrogen of the 

 food that is not stored up as increase is finally excreted in the urine. 

 The first and second columns of the table, therefore, include the ni- 

 trogenous and the mineral substances of the food, and any energy that 

 may have been expended as a result of their metamorphoses is not 

 represented in the table. 



From the data presented, it appears that more than one half (57*3 

 per cent) of the food of oxen when fattening is required in internal 

 work, or in keeping the animal machinery in repair, to say nothing of 

 the energy expended by the nitrogenous constituents, while but 6 - 2 

 per cent is stored up as increase in weight, and more than one third is 

 found in the manure. With sheep, 8*0 per cent of the food is stored 

 up as increase, less than one third appears in the manure, and 60*1 per 

 cent is used in work of the system. The pigs give 17*6 per cent of 

 the food in increase, or more than twice as much as the sheep, while 

 nearly two thirds is required for internal work, and the manure con- 

 tains less than one half as much as in the case of the oxen. The pigs 

 store up a much larger proportion of their food as increase than either 

 the sheep or the oxen, but a larger percentage is used in internal work, 

 and less appears in the manui*e. The increased expenditure in work 

 would naturally follow from the larger amount stored up as increase, 

 which involves as a matter of course an expenditure of energy in its 

 elaboration. But this is not the whole truth, as will be seen on mak- 

 ing a comparison of the figures in the first and last columns of the 

 table. For a given amount of increase stored up, the oxen actually 

 expend more in internal work than sheep, and the sheep expend more 

 than the pigs It evidently costs more, in internal work of the sys- 

 tem, to elaborate the stored-up increase from the crude feed of the 

 oxen than from the more nutritive food of the pigs. When the facts 

 are examined from a different stand-point, the relations of the increase 

 to work of the system will be more clearly seen, as in the following 

 table, which gives the results obtained from a given live weight of the 

 animals in a given time : 



