A STUDY OF ESSENTIAL PLANT FOODS RECOVERABLE 
FROM THE MANURE OF DAIRY COWS 1 
By C. F. Wells and B. A. Dunbar, Chemistry Department, South Dakota State 
College 
INTRODUCTION 
The problem briefly discussed in this 
article grew out of certain queries 
suggested by analytical results which 
the writers obtained during the prog¬ 
ress of their work done in cooperation 
with the Dairy Department of South 
Dakota State College upon the deter¬ 
mination of digestion coefficients which 
characterized dairy cattle of varied 
types under the feeding of soybean hay 
and alfalfa hay as variants. 2 
The work here reported offers a 
measure of direct information on the 
important subject of the degree of re¬ 
covery of potash, phosphorus, and 
nitrogen from the manures of dairy 
cattle during lactation periods. These 
results also afford a general comparison 
between the quantities of potassium, 
phosphorus, and nitrogen recoverable 
in the manure and the amount of milk 
simultaneously produced by the same 
cattle. This work is by no means 
complete, but it is felt it is capable of 
expansion into broader research lead- 
ng to more complete generalization 
than was possible with the limited 
number of subjects used in these di¬ 
gestion trials. 
EXPERIMENTAL DATA 
These digestion trials were conducted 
during two periods of five days each; 
the first in February and the second in 
April of 1924. For the trials four dairy 
cows, in lactation, were fed corn silage, 
oats, corn, and oil meal, as constants, 
in approximately the same quantities of 
each per day. The variant feeding ma¬ 
terial consisted of constant daily rations 
of soybean hay during the first trial and 
of alfalfa hay during the second. Each 
of these feeding materials, both con¬ 
stants and variables, was from the same 
lot originally purchased for the experi¬ 
ments, and therefore only one analyti¬ 
cal problem was presented in case of 
each of them. 
The cattle used as subjects were of 
the following breeds, and are herein¬ 
after referred to by numbers as 
assigned here: Cow No. 1, Jersey; 
cow No. 2, Ayrshire; cow No. 3, 
Guernsey; cow No. 4, Holstein. All 
were of the ordinary farm grade of 
cows, of about the same age, ranging 
closely around 5 years. At the be¬ 
ginning of the trials all were appar¬ 
ently in perfect health, and they were 
considered to be in equally good 
condition at the close of the experiment. 
At all times during the trials, as well 
as during the several weeks of pre¬ 
liminary conditioning to accustom 
them to the constant feeds and the 
methods of manure collection, the 
cows were allowed free access to salt 
and water and were cleanly bedded 
and stalled in comfort. This careful 
attention was also given in the interim 
between the trials. 
During the trials the feces and urine 
were carefully and thoroughly col¬ 
lected during 24-hour periods, and a 
composite sample of each collection 
was kept in air-tight glass containers. 
The five composites for each 5-day trial 
period were analyzed at the close of 
the period. The refuse feeding ma¬ 
terial was also collected at the close of 
the trial period and analyzed for the 
three plant-food constants, to be used 
as a drawback upon the amount of the 
several materials fed in obtaining actual 
consumption of feed per day. In 
computing the weights of each constant 
actually consumed per day, the totals 
for the trial periods were divided by 
five, and they are given on this basis 
in the tables. In the analyses of feeds 
and liquid and solid manures the writ¬ 
ers, with but little deviation, followed 
recognized methods of analysis, and 
for their immediate purposes only 
nitrogen, potassium oxide, and phos¬ 
phorus (as the pentoxide) were con¬ 
sidered. One-hundred-gram samples 
were put into solution by the use of 
concentrated sulphuric acid of specific 
1 Received for publication Aug. 18, 1924; issued July, 1925. 
2 This work was in part fulfillment of requirements for the degree of Master of Science, and was expected 
to show the relative feeding values of the hays in question. The writers are therefore indebted to the dairy 
department for certain data from which, by further analytical investigation, the material for this paper 
has been obtained. 
Journal of Agricultural Research 
Washington, D. C. 
( 985 ) 
Vol. XXX, No. 10 
May 15, 1925 
Key No. S. D. 1 
