THE VALUE OF CALCIUM PHOSPHATE AS A SUPPLEMENT 
TO THE RATION OF DAIRY COWS 1 
By J. B. Lindsey, Vice Director and Chemist , and J. G. Archibald, 2 Assistant 
Professor of Research Chemistry , Massachusetts Agricultural Experiment Station 
INTRODUCTION 
The mineral requirements of the animal system constitute a phase 
of the science of nutrition which has only within recent years attained 
any degree of prominence. From the time when Voit and his co¬ 
workers first established on a firm basis the nutritive function of those 
major constituents of foodstuffs—protein, carbohydrates, and fats— 
up until as late as the close of the first decade of the present century, 
energy values and nutritive ratios were the only standards by which 
food values were measured. Because of the prominent place which 
these factors occupy in any rational system of nutrition, it was only 
natural, and in one sense right, that emphasis should be placed on 
them to the exclusion of minor factors whose significance and impor¬ 
tance either were not realized at all, or, if realized, were but imperfectly 
understood. 
One of these minor factors was an adequate supply, both as to 
quantity and quality, of the mineral elements necessary for the proper 
functioning of the animal system. It is true, of course, that the 
necessity of the presence of these inorganic constituents in the diet 
was long ago recognized and their functions in the body understood, 
but the general conception was that an otherwise normal diet supplied 
a sufficiency of mineral matter. It was not realized that there may be 
times when the supply of mineral matter in the ration becomes a 
limiting factor in the functional well-being of the animal. Armsby 
(1 , p. 332 , 333 ) 3 sums up the situation in the following terse sentences: 
“Most feeding stuffs, however, and particularly the mixed rations of 
farm animals, contain what appears at first sight to be much larger 
amounts of ash ingredients than the body requires.” As a conse¬ 
quence the idea became somewhat prevalent “ that rations adequate 
in other respects maybe assumed to contain a sufficiency of ash ingre¬ 
dients. This is doubtless true of animals living in a state of nature, but 
it is a questionable assumption under the artificial conditions to which 
many farm animals are subjected.” 
That animals may at times suffer from a shortage of mineral matter 
in their rations is now well established. The present status of our 
knowledge on this point, and on the whole problem of mineral 
metabolism in farm animals, is due largely to several important 
researches made in recent years, and can best be outlined by a brief 
review and summary of these researches. In all the researches to be 
mentioned, the emphasis has been put largely on the metabolism of 
calcium and phosphorus, and especially on the former. There are 
1 Received for publication Jan. 26,1926; issued December, 1925. Published with the permission of the 
Director of the Massachusetts Agricultural Experiment Station. 
2 This project was planned by the undersigned with the cooperation of Mr. Archibald. The latter 
supervised the execution of the experiment, holding frequent conferences with me as it progressed. Owing 
to my many duties, it became necessary for him to prepare this paper for publication.—J. B. Lindsey. 
* Reference is made by number (italic) to “Literature cited,” p. 790. 
Journal of Agricultural Research, 
Washington, D. C. 
( 771 ) 
Vol. XXXI. No. 8 
Oct. 15, 1925 
Key No. Mass-12 
