110 INVESTIGATION IN MILK PRODUCTION. 
per cent fat from 2.5 to 6.5, are printed on pasteboard cards 
7x3 inches, and on the reverse sidea table giving the nutri- 
ents in a pound of ordinary feeding stuffs. Given the daily 
yield of milk in pounds, its per cent of butter fat, and the 
weight of the cow expressed decimally, it is an easy matter 
to determine the required ration. As an illustration, sup- 
pose a mature cow weighs 825 pounds, gives 20 pounds of 
milk daily, testing 4 per cent butter fat. One pound of 4 per 
cent milk requires of protein .0467, carbohydrates .214, and 
of ether extract, .0159, multiplying these factors by 20 it is 
found that for the production of milk she needs .934 of pro- 
tein, 4.28 of carbohydrates and .318 of ether extract. For 
food of maintenance multiply .07 protein, .7 carbohydrates 
and .01 of ether extract (maintenance formula) by 8.25 
which giyes protein .578, carbohydrates 5.78 and ether ex- 
tract .082; adding to this the nutrients required for milk 
production, we have 1.51 of protein, 10.06 carbohydrates 
and .4.0 ether extract, the nutrients required in the ration. 
They should be supplied in such manner with reference to 
bulk that it will satisfy the appetite. A ration like this 
should be largely made up of roughage. 
But suppose a cow weighing 850 pounds yields 40 
pounds of 4: per cent milk daily, the required ration would be: 
Brow Cake mat Jt, (CRIs, IkAve 
(.0467—.214—.0159)x 40=—1.868- 8.56—.636 
C07 =7 —01 )x8:50=— -595— 5:95—.085 
ee 
Ration required, 2.463-14.51-—.721 
A ration like this should be largely composed of grain so 
that it will not contain so much bulk that she will go off her 
feed, and yet furnish the nutrients required. If a cow’s ra- 
tion is adjusted in bulk with reference to her feeding capacity 
and in nutriment content to the work she is doing, she will 
not be overfed nor go off her feed. A cow will not do her 
best unless she is so fed that she is satisfied, but the ration 
should not contain more nutriment than she actually needs. 
From this it follows that cows do not require a uniform nu- 
tritive ratio in their rations, but that it varies according to 
the quantity of milk vielded and weight of cow. 
