DISEASES OF THE DIGESTIVE ORGANS. 15 



retard digestion and cause local injury to the digestive organs, but 

 they may also cause general poisoning of a severe or fatal type. 



The following molds have been shown (Dammann) to be dangerous 

 in respect of the production of the morbid conditions enumerated: 



TiUetia caries grows chiefly in wheat, and may be found with the 

 grain thus appearing in the bran or meal. It causes paralysis of the 

 throat and spinal cord and irritation of the digestive tract. The 

 rusts, such as Puccinia graminis, P. stramims^ P. coronata^ and P. 

 anuvlinacea^ cause colic and diarrhea, and in some cases partial 

 ftaralysis of the throat. The rusts that occur on clovers, beans, and 

 jDcas cause very severe irritation of the lining membrane of the mouth 

 and throat, resulting sometimes in gangrene of this tissue. 



Polydesmus exitans grows on the leaves of rape and turnips, 

 appearing in early summer. This fungus is very irritating to the 

 mouths and feet of cattle, causing severe inflammation and the for- 

 mation of a false membrane. In some instances this condition has 

 been mistaken for foot-and-mouth disease, but it can be differentiated 

 by the absence of the blister that is characteristic of foot-and-mouth 

 disease and by the further fact that it is nontransmissible. 



PolytrinciiiTn trifolii., which grows on clover, causing it to become 

 black, causes severe iiTitation of the stomach and intestines of cattle 

 feeding upon it. 



Feeds must not contain too large a proportion of woody filjer or 

 indigestible substances. If the dry matter ingested or the bulk of 

 the feed be very great on account of the small proportion of digesti- 

 ble matter, it is impossible for the great mass to be properly mois- 

 tened with and attacked by the digestive juices. In consequence of 

 this, abnormal fermentations arise that cause indigestion and irrita- 

 tion of the digestive organs. On the other hand, a ration too con- 

 centrated, and especially too rich in protein, is not suitable, becau.se 

 the animal must have, after a meal, a certain feeling of fullness in 

 order to be comfortable and quiet, and the digestive organs require a 

 relatively large volume of contents to fill them to the point where 

 secretion is properly stimulated and their activity is most efficient. 

 If too much protein is in the ration there is a waste of expensive feed, 

 and the tendency is for the animal to l^ecome thin. It is evident that 

 a cow can not thrive on concentrated feeds alone, even though these 

 contain in assimilable form all of the nutritive materials needed for 

 perfect support. It is because bulk is ne<?essai*y that the standard of 

 about 25 pounds of dry matter per cow per day has been reached by 

 experimentalists. There is no objection to feeding grain or meal 

 separately to a cow, provided enough bulky feed be fed at another 

 time in the day to keep the digestive tract sufficiently distended. 



In changing the ration, and especially in making radical changes, 

 as at the beginning and end of the pasturing season, the change 



