96 FEEDS AND FEEDING, ABRIDGED 



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

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

 1.1 lbs. of wheat bran or oats, or 1.5 to 3 lbs. of alfalfa or clover hay to 

 equal 1 feed 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. 



The feed-unit values are not true expressions of net energy, for in 

 this system feeds rich in protein are given a higher value than feeds 

 low in protein which furnish the same amount of net energy. For 

 example, in the feed-unit system, only 0.8 lb. of cottonseed meal or 

 0.9 lb. of linseed meal is required to equal 1 feed unit. Yet the real 

 net energy of these feeds is lower than that of corn. Again, the energy 

 value of timothy hay is about the same as that of clover or alfalfa hay, 

 but in the feed-unit system timothy hay is rated 50 per ct. below the 

 legume hays. When added to rations too low in protein, feeds rich in 

 protein will have a higher value than those supplying an equal amount 

 of net energy but which are low in protein. But as has been pointed 

 out in Chapters IV and V, when the ration already contains plenty of 

 protein, any additional amount will have no higher value for the forma- 

 tion of fat or the production of milk or work than an equal amount of 

 net energy supplied by carbohydrates or fat. 



The value of any feed to the stockman depends on the other feeds 

 which he has at hand. When he has an abundance of cheap car- 

 bonaceous feeds, protein-rich feeds to balance the ration will be worth 

 much more to him than an additional supply of carbonaceous feeds. 

 On the other hand, in the West with its cheap alfalfa hay and in the 

 South with its low-priced cottonseed meal, feeds low in protein and rich 

 in carbohydrates may often be worth more than those rich in protein. 

 The feed-unit system has been developed in a comparatively small 

 region, where similar crops are grown on the different farms and the 

 price of purchased feeds is quite uniform thruout the entire district, 

 hence this difficulty has not arisen there. No arbitrary values for feed- 

 ing stuffs, expressed in terms of feed units, money, or other fixed units, 

 can be devised which will hold good under such widely differing condi- 

 tions as are found in the various sections of the United States. 



Measuring economy of cows in feed units. — The chief value of the 

 feed unit system for dairymen is for comparing the efficiency with 

 which individual cows and different herds produce milk and butter 

 fat. The method of making such comparisons is as follows : 



If during a month a cow has consumed 240 lbs. of hay, 750 lbs. of 

 silage, 60 lbs. each of barley and ground corn, and 90 lbs. of linseed oil 

 meal, the calculation based on the valuation table would be as follows: 



