778 
Journal of Agricultural Research 
Vol. XXXI, No. 8 
for each cow, from 3 to 8 ounces daily, has varied with her weight and 
the amount of milk she gives, the aim being to supply approximately 
a 60 per cent excess of calcium over and above the theroetical require¬ 
ments of Kellner's standard {20, p. 618), This excess is provided 
simply as a safeguard. Little is known of how completely such 
substances are assimilated, but it is safe to assume that they are 
by no means completely utilized, and just as there must be provided 
an excess of total organic nutrients in order to have a sufficiency of 
digestible organic nutrients, so there must be an excess of total 
mineral matter. The 60 per cent excess is an arbitrary figure. 
Supplying this amount of calcium in the form of tricalic phosphate 
has also greatly increased the amount of phosphorus, so that the 
surplus of that element furnished to the “ mineral" group has averaged 
around 160 per cent. This does not mean, however, that the ratio 
of acid to base in the ash of the total ration has been materially 
increased. The rations fed as just outlined have had a considerable 
excess of bases in their ash, and as the bone meal itself has an excess 
of base over acid, the addition of the mineral supplement, although 
it has relatively enhanced very much the excess of phosphorus over 
and above requirements, has intensified rather than minimized the 
basic nature of the ash. 
ANALYTICAL PROCEDURE 
! 
Fodder and ash analyses of all Materials fed have been made as the 
experiment progressed. Total solids and fat have been made 
monthly on the milk from every cow milking at the time, and in 
addition the total ash of all milks has been determined in 12 of the 30 
months during which the experiment has been in progress, and over 
a period extending from June, 1922, to March, 1924. The calcium 
and phosphorus in the ash of the milks has been determined at'nine 
different times and ower a period extending from October, 1922, to 
March, 1924. A determination of the calcium and phosphorus in 
the drinking water supplied to the cows has also been made, 
The methods of analysis have in all cases been those of the Asso¬ 
ciation of Official Agricultural Chemists as described in the manual 
issued by that association { 2 ) ? 
The foregoing is an accurate outline of the method of procedure in 
this “long-time feeding experiment with dairy cattle under conditions 
of practice." What are the results? After two and one-half years 
of continuous feeding to half the herd of a ration deficient in calcium 
and none too .liberal in phosphorus, and to the other half the same 
ration plus sufficient supplemental mineral matter to provide a con- , 
siderable surplus of both of these elements, what can be said either for 
or against the practice of supplying mineral matter in this form ? The 
answer, so far as we have gone, is given in the next section and in the 
summary which follows it. 
PRESENTATION AND DISCUSSION OF RESULTS 
General Condition of the Animals 
An endeavor has been made to follow the condition of the animals 
closely, and observations have been recorded from month to month. 
7 Acknowledgment is made here of the services of P. H. Smith and F. J. Kokoski of the feed laboratory 
and of H. D. Haskins and L. S. Walker of the fertilizer laboratory, who did practically all of the analytical 
work in connection with the project. 
