352 THE ROTHAMSTED EXPERIMENTS. 



Propor- Of the nitrogenous compounds of food, on the other hand, 



h itro°^n, on ty a sma ^ proportion of the whole consumed is finally 

 retained stored up in the increase of the animal. In other words, a 

 and voided. ver y j ar g e amount of nitrogen passes through the body beyond 

 that which is finally retained in the increase, and so remains 

 for manure. 



It is, therefore, only what should be expected, that the 

 amount of food consumed to produce a given amount of in- 

 crease in live-weight, as well as that required for the susten- 

 ance of a given live-weight for a given time, should, provided 

 the food be not abnormally deficient in nitrogenous substance, 

 be characteristically dependent on its supplies of digestible 

 and available non-nitrogenous constituents. 

 Force and Again, it has been shown that, in the exercise of force, there 

 •'. is a greatly increased expenditure of the non-nitrogenous con- 



stituents of food, but little, if any, of the nitrogenous. 

 Food for Thus, then, for maintenance, for increase, and for the exer- 

 anc^in' c ^ se °^ f° rce > the exigencies of the system are characterised 

 crease, and more by the demand for the digestible non-nitrogenous or 

 force. more specially respiratory and fat-forming constituents, than 



by that for the nitrogenous or more specially flesh- forming 

 ones. 

 Composi- In our paper — On the Composition of Oxen, Sheep, and Pigs, 

 Hon of anc i f th e i r Increase whilst Fattening — published in I860, 1 



r CC7b SfLEPT) 



and pigs. ' we concluded that — if fattening oxen were liberally fed 

 upon good food, composed of a moderate proportion of cake 

 or corn, some hay or straw chaff, with roots or other 

 succulent food ; if sheep were fattened under somewhat simi- 

 lar conditions, but with a less proportion of hay or straw ; 

 and if pigs were liberally fed chiefly on cereal grain — the 

 increase would, with as much as 5 or 6 parts of total non- 

 nitrogenous to 1 of nitrogenous compounds in the dry sub- 

 stance of such fattening food, probably be very fat. Further, 

 that in the earlier stages of growth and feeding, a lower pro- 

 portion of total non-nitrogenous constituents, that is, a higher 

 proportion of the nitrogenous compounds, is desirable ; in- 

 deed, that it is frequently the most profitable, having regard 

 both to the rapidity of fattening and to the value of the man- 

 ure, for the farmer to employ, even up to the end of the feed- 

 ing process, a somewhat higher proportion of nitrogenous 

 constituents in his stock-foods, than is necessary to yield the 

 maximum proportion of increase in live-weight for a given 

 amount of dry substance of food consumed. But that, when 

 the mixed fattening food contains less than about 5 parts of 

 non-nitrogenous to 1 of nitrogenous compounds, the propor- 



1 Jour. Roy. Ag. Soc. Eng., 1st Series, vol. xxi., 1860, p. 433. 



