DAIRYING 49 



736. The nutritive ratio of the feed is a matter of considera- 

 ble importance and this should be determined as well as the 

 amount and the composition of the feed. 



Many feeding experiments have shown that for cows produc- 

 ing milk the nutritive ratio should be about 1 :7. This means that 

 the daily feed per cow should contain one part digestible protein 

 to seven parts digestible carbohydrates. As an illustration of a 

 nutritive ration calculation take the figures from the table above 

 for corn meal. These are digestible protein 7.9, digestible car- 

 bohydrates 76.4, and dividing 76.4 by 7.9 gives 9.67, showing the 

 nutritive ration of corn meal to be 1 :9.67. 



737. Calculating a ration from the standards given let us 

 as'sume that the cow weighs about 1000 pounds and she is giving 

 milk that contains 1 pound of butter fat per day. The table 

 shows that the daily feed of such a cow should be about 23 pounds 

 of dry matter and this should contain about 16 pounds digestible 

 dry matter and 2 pounds digestible protein. Selecting some of 

 the more common feeds from the table, a ration that nearly satis- 

 fies this requirement will be made up as follows : 



Digestible 



Dry Protein Carbohydrates 

 Matter Ibs. Ibs. 



30 pounds corn silage 8.85 .36 5.43 



8 pounds clover hay 6.78 .54 3.17 



2-4 pounds corn meal 3.56 .32 3.06 



4-6 pounds wheat bran 5.32 .70 2.86 



2 pounds oil meal . . . : 



24.51 1.92 14.52 



Nutritive ratio 1:7.5 or 14.52^1.92. 



738. This ration gives 24.5 pounds dry matter instead of 23 

 pounds ; 1.92 pounds digestible protein instead of 2 pounds, and 

 1.92 + 14. 52 = 16.44 pounds digestible dry matter instead of 16. 

 The nutritive ratio is 1 :7.5 instead of 1 :7. It comes, however, 

 near enough the standards to make a satisfactory feed for cows of 

 this weight and producing 1 pound of butter fat in the milk 

 daily. The important problem to be considered after clearly 



