398 
IOWA ACADEMY OF SCIE’KCB 
more naturally run are those of the ‘ ‘ appetite ’ ’ fed pigs, provid 
ing these lines are smoothed out on a ‘‘general average basis 
Dietrich found that his standard was more satisfactory than 
the Wolff-Lehmann one. If that is true then it would seem that 
the “appetite ’’-fed pigs are certainly nearly right, and there 
is a question whether or not they would not excel Illinois stand- 
ard fed pigs. 
Investigations are now in progress at the Iowa Agricultural 
Experiment Station in which the Illinois standard, the Wolff- 
Lehmann standard, and the freedom of choice or appetite sys- 
tem are being compared. 
The ratio of crude nutrients (pounds of carbohydrate equiva- 
lent eaten with every pound of protein) has been worked out for 
the two discussed standards — the Dietrich and the Wolff- 
Lehmann, as well as for the free-choice system fed pigs. The 
close similarity of the ratios until the pig reaches about 190 
days of age is quit© strikingly evident. At this time, however, 
(187 days) the Dietrich ratio curve mounts to an almost in- 
conceivable height, and then on reaching its maximum on the 
210th day comes quickly down again to the apparently normal. 
This marked widening of the Dietrich ratio at this time is pri- 
marily due to the very rapid decrease in protein inaugurated 
on the 187th day. This decline continues until the 213th day 
when a level is reached. On the same day that this low level 
point of protein allowance is reached (213th day) the ratio be- 
gins to narrow, as is evident from Plate XLIV (compare Plates 
XLII and XLIY on this point). 
Taking everything into consideration, the ratio of crude nu- 
trients in the two standards and the “appetite” scheme more 
closely agree than the crude protein and the crude carbohydrate 
equivalent, consumption daily to a thousand pounds live weight. 
The disagreements, however, are clearly evident. 
The Wollf-Lehmann standard approximates the “appetite” 
curve very closely up to the 175th day or thereabouts but from 
that time on it calls for a much narrower ration (which is more 
expensive, generally, though not always, from the animal hus- 
bandman’s standpoint, than the ratio chosen according to the 
appetite). Practical men for the most part assuredly wish that 
the “appetite” curve as compared to the Wolff -Lehmann re- 
quirement be more nearly correct, because the former is more 
economical, ordinarily, likewise easier to accomplish. 
