178 PHYSIOLOGY OF THE DOMESTIC ANIMALS. 



to- rise above 125 F. the ferments are destroyed and the production 

 of organic acids thus largely prevented, and a sweet silage is produced 

 which possesses the characteristics of old hay to a much more marked 

 extent than by the old or "sour" process. This process is especially 

 valuable in wet seasons as a means of preserving the crop. It is also 

 invaluable for preserving second crops. A succulent food is obtained in 

 place of a dry one with but little loss in nutritive constituents ; certainly 

 less than occurs during hay-making in wet weather, although there is but 

 little increase in the digestibility of the grass. 



Vegetable matters all contain from two to eight times as much potas- 

 sium as sodium, and, as we shall again refer to under the subject of 

 Nutrition, explains the fact that the herbivorous animals need an extra 

 ration of sodium chloride. 



Straw is difficult to digest, is only but slightly nutritive, and requires 

 large quantities of the digestive secretions for the solution of its nutri- 

 tive constituents. Straw is somewhat more readily digested by the 

 ruminants than by the horse. Straw, of different kinds, has about the 

 following composition : 



100.0 100.0 100.0 100.0 



Yery frequently various forms of vegetable food will produce dis- 

 turbances of digestion in the domestic animals from the mixing with 

 them of various forms of adulteration, or. from various defects in the 

 character or quality of the food. The capability of recognizing .this in 

 a general way is, therefore, desirable. Thus, spoiled hay or hay which 

 has lost its inorganic constituents likewise loses its normal greenish color, 

 and is of a dirty-gray or brown tint ; while acid fermentation or putre- 

 faction in all fodders may be recognized by the characteristic odor and 

 taste. Good oats must be clean and composed of perfectly-formed mealy 

 granules, and possess a certain definite specific gravit}'. Unripe or 

 frozen oats have a less specific gravity and a less nutritive value, while 

 spoiled oats are recognized by a musty smell and an unpleasant, burning 

 taste. The quality of the ha}^ will, of course, depend upon the quality 

 of the ground and its botanical constituents, the time of cutting, and 

 the mode of preservation. In order to judge of the quality and nutri- 

 tive value of hay it may be divided into three different groups. In the 

 first group are the sweet grasses (graminese)', in the second, the acid 



