A STUDY OF RATIONS FED TO MILCH COWS. 69 
Table 5 on pages 65 to 68, gives a summary of 38 rations 
used in feeding the dairy herds studied by the Station. Nine 
of these rations were, however, suggested by the Station, and 
therefore only 29 of them actually represent the feeding prac- 
tice of these dairymen. 
The total weights of food fed per 1,000 pounds live weight 
are given in the first column of figures. As explained above, 
all of the foods used in these experiments were carefully 
analyzed and their chemical composition is therefore known. 
The weights of digestible nutrients were obtained by the use 
of factors (digestion coefficients), as explained on page 58. 
The last column but one contains the nutritive ratio, and the 
last column gives the calculated fuel value of the digestible 
nutrients in the rations. 
It is possible to compare different rations by the quantities 
of digestible protein or flesh formers which they contain and 
the fuel value of their digestible nutrients. The extremes of 
these rations are pointed out in the following table, by com- 
paring the maximum and minimum of organic matter, protein, 
fat, carbohydrates, fuel value, and nutritive ratio of all the 
rations in each case: 










: ; Fuel Value 
Organic | Digestible| Digestible eee of Nutritive 
Matter. Protein. Hatem hydrates Digestible Ratio. 
"| Nutrients. 
Lbs. Lbs. lbs: Lbs. Calories. ng 
Minimum, 27rations,| 20.5 fie es .56 10.47 28600 4.5 
Maximum,27rations,| 33.7 3.48 1.36 18.25 |- 42600 1 ee: 
Average, 27 rations, 95.9 9.36 .87 13.76 33650 6,7 
RATIONS FOR MILCH COWS. 
A proper ration for an animal must supply the materials 
needed for the maintenance of its body and for the production 
demanded from it. ‘ 
The amounts and proportions of these nutrients needed for 
the physiological demands will vary with the animal and with 
the kind and amount of production. For maintenance the body 
needs certain amounts of material, chiefly protein, to build its 
tissues and keep them in repair, and certain amounts of other 
materials, chiefly carbohydrates and fats, to serve as fuel for 
supplying the energy which the body needs for heat and work. 
For growth, the proportion of protein must be liberal. For 
6 
