240 THE FEEDING OF ANIMALS 



many years been a standard crop for feeding purposes. 

 This class of crops has the advantage of furnishing very 

 palatable, succulent food, which may be kept in per- 

 fect condition during the entire winter season, an advan- 

 tage which is not wholly measured by the actual quan- 

 tity of nutrients supplied by these materials. 



The disadvantages of these crops are that they are 

 somewhat expensive to grow and necessitate the hand- 

 ling of large weights of water. A ton of turnips or man- 

 gels may furnish even less than 200 pounds of dry sub- 

 stance, to secure which 1,800 pounds of water must be 

 lifted several times. The percentage of dry matter in 

 roots and tubers varies in American products, on the 

 average, from 9.1 per cent in mangel-wurzels and tur- 

 nips to 28.9 per cent in sweet potatoes. Potatoes are 

 more nutritive pound for pound than roots. The dry 

 matter of this class of cattle foods is principally carbo- 

 hydrate in its character, though the proportion of pro- 

 tein is as large and in some cases larger than in certain 

 grain foods. 



Two conditions are essential to the winter storage of 

 roots without deterioration, viz., a low temperature, 

 as near freezing as possible, and abundant ventilation. 

 Large masses of roots un ventilated are apt to "heat," 

 and sometimes decay, with a resulting large loss in nutri- 

 tive value. 



GRAINS AND SEEDS 



328. The conditions which provide for the mainte- 

 nance of plant life also subserve the interests of the animal 

 kingdom. We have seen that this is true of the store 

 of starch and other compounds in tubers and roots, 

 and it is a fact of much larger significance in the produc- 



