776 Journal of Agricultural Research voi. xxxi, nq. a 
50 grams each of calcium oxide and phosphoric acid. Expressed as 
the elements (Ca and P) 5 and on a pound basis the standard is as 
follows: A cow weighing 1,000 pounds requires for maintenance 
(daily), 0.07 pound calcium, 0.021 pound phosphorus; for each 
pound of milk produced, 0.002 pound calcium, 0.001 pound 
phosphorus. 
The analytical data which have been employed in adjusting the 
rations to the standards have been very carefully compiled from a 
large number of analyses and digestion studies of the several materials 
fed. In the case of the mineral constituents of the various feeds, it 
was found at the start of the experiment that comparatively few 
analyses had been made, so a separate project 6 was organized and the 
mineral constituents of a large number of samples oi the roughages 
and concentrates fed were determined. 
Rations Fed 
As already stated, the ration fed has designedly been as poor in 
mineral matter as a wise choice of feeds, other factors being considered, 
would permit. It has not been possible or even desirable to feed the 
same identical ration at all times, but the content of digestible 
nutrients has been kept as constant as possible throughout. The 
following is an accurate account of the various modifications in the 
rations: 
Hay. —The hay fed was all grown locally, most of it on the station 
farm, and it has all been of the same general character, consisting for 
the most part of timothy with some redtop, bluegrass, and orchard 
grass. In all purchases of hay, a minimum of clover has been insisted 
on and none of the hay fed has contained more than a very small 
percentage of it. Some of the lots fed have not had even a stray 
stalk of clover. The average amount of calcium in these hays has 
been 0.47 per cent and of phosphorus 0.19 per cent. In order to 
impoverish the ration still further with respect to calcium and 
phosphorus, for the past year and a half a portion of the hay has been 
withheld and such mineral-poor materials as chopped oat straw 
starch, and dried apple pomace have been successively substituted 
for it. The cklcium and phosphorus content of these has been: 
Oat straw, 0.38 per cent Ca, 0.14 per cent P; starch, none; dried apple 
pomace, 0.11 per cent Ca, 0.11 per cent P. 
Green soiling crops have been fed during the summer in place of a 
portion of the hay. During the first summer the experiment was in 
progress (1922) no departure was made from the long-established 
custom of feeding a maximum of 50 pounds of green feed per cow daily 
and of including in the succession of soiling crops such legumes as 
field peas and soy beans. Realizing that here might be a possible 
source of more calcium than would be desirable to feed under the 
conditions of the experiment, the amount fed was cut down last year 
(1923) to a maximum of 25 pounds daily, peas were eliminated from 
the rotation, and only a minimum of soy beans was fed. For a similar 
reason and as previously noted, the dry cows were not sent to pasture 
last summer (1923). 
8 The writers in all their work have reduced their Ca and P figures to the elemental basis, not CaO and 
P2O5. 
8 Results of this project are as yet unpublished. 
