FEEDING OF ANIMALS. 263 



especially in the earlier years, it was, owing to the amount of 

 labour involved, found to be impracticable to do more in the 

 way of analysis cf the foods than to determine in them the 

 percentages of dry substance, of mineral matter, of nitrogen, Analysis 

 and sometimes of fatty matter. From the results were calcu- °''° s ' 

 lated the amounts of total nitrogenous substance, of total non- 

 nitrogenous organic substance, and of total organic matter, 

 which the food supplied. 



At that time little or nothing had been done in the way of Calcuiat- 

 determining, either the condition of combination of the nitro- Tg^^and 

 gen in vegetable foods, or the character of the non-nitrogen- non-nitro- 

 ous bodies. The only method then practicable was, to calcu- ^^ t c s on " 

 late the amount of nitrogenous substances from the amount 

 of nitrogen, a plan which we pointed out was liable seriously 

 to mislead, if due allowance were not made for differences in 

 the composition, and condition, of the substances so estimated. 

 In the case of ripened final products, such as cereal grains, 

 and the leguminous seeds, there is comparatively little error 

 in so reckoning the whole of the nitrogen to exist as albu- 

 minoid bodies ; in hays and straws there is a much larger 

 proportion of the total nitrogen non-albuminoid; and in 

 succulent products, such as roots and tubers, much more still. 



Then, again, the proportion of the non-nitrogenous organic Digestible 

 substance which is digestible is very different in different aiaestibie 

 vegetable products. Thus, in hays and straws there is a large constitu- 

 proportion of indigestible woody fibre, in cereal grains and ents - 

 leguminous seeds much less, and in roots and tubers very 

 little. 



We shall, nevertheless, find that when, as was always done 

 in our interpretation of the results, due reservation is made 

 as to the character, both of the so-reckoned nitrogenous and 

 of the non - nitrogenous organic substance of the different 

 foods, the indications are very clear and significant as to 

 whether, taking our fattening food - stuffs as they go, their 

 comparative food-value is measurable, more by their contents 

 in digestible nitrogenous, or in digestible non - nitrogenous, 

 constituents. 



The investigations also involved the determination of the Composi 

 composition, and especially of the amounts and the proportion ^ m ^ 

 of the nitrogenous, and of the non-nitrogenous constituents, bodies and 

 in the bodies of the animals themselves, and in their increase excrements - 

 whilst fattening ; and it also involved that of the composition 

 of the excrements, that is, of the manure. 



Thus, the inquiry embraced the following points : — Points em- 



1. The amount of food, and of its several constituents, con- braced in 

 sumed in relation to a given live-weight of animal, within a e x P eli- 

 given time. ments. 



