Experiments on the Feeding of Sheep. 
207 
compounds than upon an increased amount of the nitrofi^cnous 
ones. 
The comparison between the results of Pen 3 and Pen 4 — the 
former with barley, and the latter with a theoretically equivalent 
mixture of beans .and linseed-oil — is of especial interest. 
If we suppose the amount of beans and oil actually ado])ted 
in Pen 4 to have represented exactly, in theoretical equivalent, 
the barley of Pen 3, so far as the mere siipph/ of flesh-forming- 
and respirable and fat-forming material is concerned, the result 
would show, in practice, a marked superiority where a certain 
portion of starch was substituted by its calculated equivalent of 
oil — that is, 2|- parts of starch by 1 part of oil. Thus, the 
amount of barley required was somewhat more than theoreti- 
cally e([uivalent to the amount of beans and oil consumed to 
produce 100 lbs. increase in live-weight ; and there were, be- 
sides, about 50 lbs. more hay consumed with the barley than 
with the beans and oil to yield that amount of increase. Again, 
the average proportion of carcass in the fasted live-weight 
was nearly 3 per cent, greater, and the average amount of inside 
loose fat nearly time greatei-, in the sheep fed upon hay, beans,, 
and oil, than in those fed upon hay and barley. 
So far as can be judged, the amounts of beans and oil actually 
consumed per 100 lbs. live-weight in Pen 4 were perhaps slightlj 
more than equivalent, even theoretically, to the barley taken in 
Pen 3 ; but certainly by no means sufficiently so to account for 
the marked difference in the result. There are, indeed, sufficient 
reasons for concluding that, independently of mere supj)!)/ of con- 
stituents, the conditions of their concentration and digestibility, 
and consequently of their assimilability, must have an influence in 
determining the relative values for the various requirements of the 
body, of substances which, in a general, or more purely chemical 
sense, may still be justly looked upon as mutually replaceable ; 
and although starch and oil are undoubtedly, within certain limits, 
mutually replaceable in about the proportions above stated, it seems 
but reasonable to suppose that the tax upon the system will be less 
in the appropriation of ready-formed fat than of starch from which 
it may be formed — at any rate for fat-storing, if not for respiration 
also. The results of these two experiments, so far as they go, afford 
evidence in favour of the view that such is in reality the case. 
That in human dietaries there is an advantage in having a por- 
tion of the non-nitrogenous matter supplied in the form of fat 
(as in animal food), instead of nearly the whole of it as starch 
and allied substances (as in bread, sugar, &c.), cannot be doubted. 
In fact, one great object attained in fattening animals for the 
food of man seems to be to get crude non-nitrogenous vegetable 
products ready formed into fat for his use. 
