128 FEEDS AND FEEDING 



the starch in feeds ferments in the digestive tract. On the other hand, 

 in cattle upwards of 10 per ct. of the heat value of the digested food is 

 lost in methan gas and about 7 per ct. is wasted, so far as productive 

 purposes are concerned, in the heat produced in the fermentations. 

 (79-80) Accordingly, with horses and pigs starch will have a higher 

 value compared with fat than in the case of ruminants. 



It should also be remembered that the Armsby standards are based 

 on only the digestible protein in various feeds, not including the amids. 

 It has previously been pointed out that recent investigations make it 

 appear preferable to compute balanced rations on the basis of the 

 digestible crude protein the different feeds contain. (94) 



We must thus regard the present net energy values of feeding stuffs, 

 not as exact measures of their value for all classes of animals, but as 

 approximations which are most helpful in teaching great principles in 

 the feeding of live stock. 



From the foregoing discussion the wise feeder will see the importance 

 of studying carefully the results actually secured with different combina- 

 tions of feed when fed to the various classes of animals, as presented in 

 detail in the respective chapters of Part III. 



VI. THE SCANDINAVIAN FEED-UNIT SYSTEM 



A system of feed equivalents, based mainly on the experiments with 

 milk cows and swine by Fjord and his successors in Denmark and the 

 investigations of Hansson in Sweden, has been adopted in Denmark and 

 other Scandinavian countries, especially by the cow-testing associations, 

 for measuring the relative values of different feeds and the efficiency of 

 cows. This system is also used to a less extent with pigs and other 

 classes of animals. For the reasons pointed out later, it has never been 

 used to any large extent in this country. 



178. The feed unit. The feed unit of the Danish associations is 1 Ib. of 

 standard grain feed, such as corn and barley, or their equivalents in feed- 

 ing value. In Sweden it is one kilo (2.2 Ibs.) of barley or its equal in 

 other feeds. All feeding-stuffs are reduced to this standard in cal- 

 culating the feed consumption of the animal. The amounts of various 

 feeds required to equal 1 feed unit are shown in the following table. 



The table shows that corn, wheat, rye, barley, homiAy feed, the dry 

 matter in roots, etc., are all considered to have about the same value for 

 the dairy cow, 1 Ib. equaling 1 feed unit. On this basis it requires 1.1 

 Ibs. of wheat bran or oats, or 1.5 to 3 Ibs. of alfalfa or clover hay to equal 

 1 unit. Cottonseed meal, linseed meal, dried distillers' grains, gluten 

 feed, and soybeans are rated at a higher value than the same weight of 

 corn or wheat, less than a pound of these concentrates being required for 

 a feed unit. 



