CALCIUM AND PHOSPHORUS IN THE FEED OF DAIRY COWS. 7 
mals should have plenty of calcium in their rations, and therefore all 
received alfalfa hay in quantities which it was hoped would provide 
sufficient calcium. 
The details of the experimental procedure and the results obtained 
are given in the description and tables at the end of the article. 
The experiments consisted essentially (a) in drying cows off about 
60 days before they were due to calve, (b) in feeding the controls a 
certain basal ration, (c) in feeding the others the same basal ration, 
giving grain and hay on alternate days and adding sodium phos- 
phate to the grain, and (d) in following the milk yields from the 
tenth to the fortieth day after calving. 
Some of the animals used in the experiments were from the general 
herd, and had previously been fed approximately according to the 
Savage feeding standard. Others had been on test during the year 
preceding the experiments, and had been fed much more liberally. 
In the case of the animals from the general herd (see Tables 1 and 2) 
the alternated feeding with phosphate had a very favorable influence 
on the subsequent milk yield ; but in the case of those which had been 
on test (Table 3), the effect was insignificant. This indicates that 
the rations fed to the general herd were deficient in one or both of the 
principal bone-building elements. 
The results show that the effect of the alternated feeding with 
phosphate on the subsequent milk yield will depend on the previous 
history of the cows as well as on the amount of phosphorus contained 
in the basal ration. It follows that the quantitative results of the 
experiments are significant only for the special conditions under 
which they were carried out. They might be entirely different in a 
herd whose previous history had been different, or with a basal ration 
which contained a different amount of phosphorus. 
The attempt has been made, however, to get an approximately 
quantitative idea of the increase in milk yield produced by the phos- 
phate feeding under the conditions of experimentation used with the 
cows of the general herd. For this purpose, only those animals have 
been considered which figure both as controls and as experiment ani- 
mals and whose histories are given in Table 1. The method and 
results used in this attempt are given in Table 8 with its appended 
comment and in figure 3. The animals gave, on the average, 37.9 per 
cent more milk after the phosphate feeding than would have been 
expected from their previous performance. 
The milk yield from the tenth to the fortieth day after calving 
has been taken as the most important measure of the effect produced 
by the alternated feeding with phosphate during the preceding dry 
period. But certain other aspects of the effect produced by this 
treatment have also been studied. 
