A PRACTICAL FEEDING RATION. 221 



sought. Since there is a great variety of different foods, and 

 almost infinite possible combinations of these, it would not do to 

 express these requirements in so and so many pounds of corn, or 

 oats, or wheat bran, but they are in all cases expressed in 

 amounts of digestible protein, carbohydrates and fat. This en- 

 ables the feeder to supply these food materials in such feeding 

 stuffs as he has on hand or can procure. The feeding standards 

 commonly adopted as basis for calculations of this kind are those 

 of the German scientists, Wolff and Lehmann. Those standards 

 give, then, the approximate amount of dry matter, digestible pro- 

 tein, carbohydrates, and fat, which the different classes of farm 

 animals should receive in their daily food in order to produce 

 maximum returns. We have seen that a fair amount of digestible 

 protein in the food is essential in order to obtain good results. 

 The proportion of digestible nitrogenous to digestible non-nitro- 

 genous food substances therefore becomes important. This pro- 

 portion is technically known as nutritive ratio, and we speak 

 of wide nutritive ratio, when there are six or more times as much 

 digestible carbohydrates and fat in a ration as there is digestible 

 protein, and of a narrow ratio, when the proportion of the two 

 kinds of food materials is as 1 to 6, or less. 



The feeding standards given in the following tables may serve 

 as a fairly accurate guide in determining the food requirements 

 of farm animals; and it will be noticed that the amounts are per 

 1,000 pounds live weight, and not per head, except as noted in the 

 case of growing animals. The standards should not be looked 

 upon as infallible guides, which they are not, for the simple rea- 

 son that different animals differ greatly both in the amounts of 

 food that they consume and in the uses which they are able to 

 make of the food they eat. The feeding standard for milch cows 

 has probably been subjected to the closest study by American 

 experiment station workers, and it has been found, in general, 

 that the Wolff-Lehmann standard calls for more digestible protein 

 (i. e., a narrower nutritive ratio) than can be fed with economy 

 in most of the dairy sections of our country, at least in the 

 central and northwestern states. On basis of investigations along 

 this line conducted in the early part of the nineties, Prof. Woll, 

 of Wisconsin, proposed a so-called American practical feeding 

 ration, which calls for the following amount of digestible food 



