134 STORRS AGRICULTURAL EXPERIMENT STATION. 
seem to call for differences in the amounts of food, but an 
increased milk flow calls for a larger ration, more especially 
a larger amount of digestible protein, in order to meet the 
increased demands on the system of the animal. 
This subject was discussed in the Report of this Station for 
1897 (pp. 119-129) and rations were proposed for feeding cows 
according to the milk yield. It was suggested tentatively that 
for a milk yield under twenty pounds per day there should be 
given a basal ration furnishing about two pounds of digestible 
protein, while for every five pounds increase in the daily milk 
yield there should be added one pound of protein mixture fur- 
nishing approximately a third of a pound of digestible protein. 
EXPERIMENTS DURING THE WINTERS OF 1897-8 AND 1898-9. 
In order to study the value of rations for milch cows based 
upon milk yields, preliminary experiments were put in opera- 
tion during the seasons 1897-1899. These experiments were 
made with three different herds, but various unavoidable cir- 
cumstances rendered the results unsatisfactory, so that they 
have not been published. So far as they show anything, 
however, they point to a fact that had already been recognized, 
namely, that ordinarily the rations should be increased rather 
in proportion to the increase of total solids in the milk than to 
total milk yield. It would be somewhat difficult, of course, 
for the dairyman or farmer to determine readily the amount of 
solids in milk; but an approximate measure of the variations 
in the total solids may be found in the variations in the amount 
of butter fat in the milk, since the quantity of the other solid 
ingredients (casein, sugar and ash) remains fairly constant in 
ordinary milk; that is to say, a variation in total solids of milk 
is ordinarily due to a variation in butter fat rather than in 
the other ingredients. | 
PLAN OF EXPERIMENTS DURING THE WINTER OF 1899-1900. 
In the winter of 1899-1900 tests were made with four herds to 
study the effect of feeding according to the yield of total solids 
in the milk as measured by the amount of butter fat. These 
experiments are reported in detail in the following pages. 
Each experiment consisted of two tests. In the first test the 
herd was fed according to the usual practice of the dairyman, 
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