£00 TWENTY-FIFTH ANNIVERSARY REPORT. 
was given to feed such when necessary and not bone ash or Florida 
rock, The insertion of these comments in a conspicuous place at 
the end of the report of the work was justified, for at once and at 
intervals after its publication inquiries were received as to how 
much bone ash and ground rock to feed and where it could be 
obtained. 
THE ADAPTABILITY OF CONCENTRATED BY-PRODUCTS FOR POULTRY 
FEEDING. 
Because the ordinary grains and coarse foods which must usually 
constitute the bulk of the ration for poultry do not supply the pro- 
portion of protein and mineral matter needed at times, concentrated 
by-products of various kinds are fed. Foods which differ little in 
protein content as ordinarily determined, or in cost, do not corre- 
spond closely in efficiency. Sometimes palatability seems the chief 
cause for difference, and sometimes the condition of the food as 
affecting digestibility. Often the reasons for different effects are 
not very obvious. 
The adaptability of many of these materials cannot be satis- 
factorily determined except by observing the effects of their use 
under various conditions. As contributing toward knowledge in’ 
this line the results from a few feeding trials in which several con- 
centrated by-products were freely used were reported. As young 
birds show the effects of questionable foods plainer than older 
ones, young chicks and ducklings were used in these trials.2* The 
general results may be summarized as follows: 
Of three highly nitrogenous rations fed to ducklings, one con- 
taining dried blood and bone meal was associated with much slower 
rate of growth than one containing animal meal and another con- 
taining “milk albumen” and bone meal, though the same amount 
of food under each ration gave equal increase in weight. The 
superiority of the two rations seemed due almost entirely to their 
greater palatability. 
Of four rations carrying much Beta a food one containing 
a large proportion of gluten meals proved inferior, when fed to 
chicks, to another having in addition bone meal, and much inferior 
to others in which most of the gluten meal was replaced by animal 
meal or by a by-product called “ milk albumen.” Unpalatability 
seemed to a large extent responsible for the inferiority of the 
* Bul. 271; -also in. Rpt. 24:37-42 (1005). 
