98 TWENTY-FIFTH ANNIVERSARY REporT. 
corded feeding was begun when the ducklings were one week old 
and was continued for ten weeks. 
During the first three weeks less food was required for the same 
increase in weight and the rate of growth was fastest for the lot 
having the “60 per ct. ration.” Up to eight weeks of age the 
greatest increase in weight was made by this lot, and the average 
amount of food per pound gain was no greater than for any other 
lot. On the average for the entire time the amount of dry matter 
in the food for each pound gain in weight was greatest for the lot 
having the most animal meal, or the “80 per ct. ration,” the 
amount required by the other lots being about alike. During the 
later periods (and also for a time by the same lot under a more 
fattening ration) growth was made at a somewhat more economical 
expenditure of food under the ration in which 20 per ct. of the 
protein came from animal food, but was slower. Under the rations 
containing larger proportions of animal food marketable size was 
reached about two weeks sooner. At twelve weeks of age the 
largest birds in the lot fed the “8o per ct. ration” exceeded the 
largest in the lot fed the “20 per ct. ration” by about 18 per ct. 
The largest in the other two lots were intermediate in size. 
Results on the whole favored the use for the first four weeks 
of a ration in which 60 per ct. of the protein came from animal 
food, and later, rations containing larger and increasing proportions 
of grain foods. 
THE IMPORTANCE OF MINERAL MATTER AND THE VALUE OF GRIT 
FOR CHICKS. 
With rations composed of the grains and foods in ordinary use 
the benefit derived from addition of the animal by-products lies in 
several directions. Almost always they make good a lack of protein 
and generally they improve the palatability; but sometimes when 
the ration is palatable enough and supplies enough protein the 
benefit is chiefly due to the mineral matter they contain. The ad- 
dition of bone ash alone to rations, otherwise entirely of vegetable 
origin, was found to bring them equal in efficiency for growing 
chicks to similar rations with animal food. It was not certain to 
what extent such inorganic material was of direct nutritive value 
and how much of purely mechanical assistance. Much of the bone 
ash was in particles like sand, and when sand was added to the 
food of chicks better results followed. 
In collecting information on this point and to get further sug- 
