54 FEEDS AND FEEDING, ABRIDGED 



Haeeker of the Minnesota Station. 2 He found that dairy cows under 

 good care and otherwise liberal feeding continued a good flow of milk 

 for long periods on a very small allowance of crude protein. After 

 some years of such feeding, however, the vitality of these cows was so 

 undermined that they became physical wrecks long before their time. 

 Even when sufficient protein is fed to insure good health, the amount 

 required to maintain mature resting animals is not large compared 

 with the need for carbohydrates and fat for body fuel. The main- 

 tenance rations for such animals may therefore have a relatively wide 

 nutritive ratio. For example, rations for maintaining full-grown 

 steers may have as wide a nutritive ratio as 1 :10 or even 1 :16 and 

 for horses as wide as 1:8 or 1:9. (See Appendix Table V.) 



When more protein is fed than is needed to repair the tissues of the 

 body, the nitrogen is split off the excess portion and excreted in the 

 urine. The non-nitrogenous part which remains is not wasted, but 

 may be used for body fuel just as are carbohydrates and fat, or it may 

 be changed into glucose and possibly finally stored as fat in the 

 body. 



Can amids replace protein? — Whether the group of nitrogenous 

 compounds, more simple than the proteins, which are included under 

 the term amids (see Page 10), can serve the same purpose in the 

 body as the true proteins, is still a disputed question. Numerous 

 trials have shown that animals cannot live on a single amid as the 

 sole source of nitrogen. However, it is reasonable to believe that 

 when a mixture of amids in a feeding stuff contains all the different 

 amino acids (the protein building-stones) needed to form body pro- 

 tein, these amids can then be used in the same manner as true protein 

 for the repair of body tissues and for the formation of new protein 

 tissue. This belief is upheld by the following: Nearly half the 

 nitrogen in corn silage and only about 15 per ct. of that in dried corn 

 forage is in amid form. Yet, based on the dry matter content, corn 

 silage is somewhat more valuable than dry corn forage as a feed for 

 dairy cows, which require a liberal supply of crude protein. Like- 

 wise, the amids are abundant in grass, roots, and silage, which are 

 especially useful for growing and pregnant animals and for those 

 producing milk or wool — all of which are in particular need of abun- 

 dant protein. 



III. Requirements fob Mineral Matter 



Importance of mineral matter. — The necessity for an ample supply 

 of mineral matter is shown by feeding animals rations freed as far 

 as possible from it. Even tho the rations contain an abundance of 



2 Minn. Buls. 71, 79, 140. 



