25 



dead. The autopsy at 9 a. m. October 18 showed slight hemorrhages 

 in the trachea, lungs hemorrhagic, kidneys congested; the heart had 

 severe hemorrhages, both internally and externally. 



Case No. 12 A yearling calf weighing 220 pounds was fed three- 

 fourths of a pound of dry leaves at 5 p. m. July 21, 1920, which was all 

 eaten next morning. At 8 a. m. the animal was sick and walked with 

 an unsteady gait. The incoordination was most marked in the hind 

 legs, especially the left hind leg. The back was curved to the right. It 

 kept getting worse during the afternoon, and was found dead next 

 day at 7 a. m. The autopsy at 9 a. m. showed the lymph glands hemor- 

 rhagic. There was acute inflammation of the liver and of the bladder. 

 Small hemorrhages were found on the heart. The meninges of the 

 brain were congested in region of the cerebrum. There were minute 

 pin-point hemorrhages in the gray matter of the brain; these were 

 more marked in the left side than in the right. These hemorrhages 

 were located in the corpus striatum and in the medullary portion of 

 the cerebrum and cerebellum. 



The Time of the Year When Milkweed Is Poisonous. 



All the feeding tests and field observations clearly indicate that this 

 milkweed is poisonous at all times .of the year. Animals have been 

 poisoned and killed by plants collected in the spring of the year when 

 they were just a few inches high, and by plants collected at later stages 

 of growth up to the time when they had become fully matured and 

 dried up in the fall of the year. Losses, therefore, may occur at any 

 time when hungry animals feed upon this milkweed. 



Prevention of Losses. 



There is no known remedy for an animal badly poisoned with this 

 plant. Consequently, to avoid losses it is necessary to understand the 

 conditions under which an animal is most likely to eat a fatal dose. 

 The fresh green milkweed as it grows in the field is not relished by any 

 class of live stock and is eaten only under stress of hunger. This is not 

 the case when it is cut and dried and put up in hay, for it then loses a 

 large part of its disagreeable taste and is quite readily eaten. Thus hay 

 containing this milkweed is always dangerous. On the other hand, 

 ranges or pastures where this plant grows are not always dangerous, 

 providing there is enough grass or other forage to satisfy the animals. 

 Thus the losses occur (1) when hungry animals are being herded along 

 driveways or trails where there is little or no feed for stock; (2) when 

 stock are pastured on overgrazed or very closely grazed ranges sup- 

 porting this plant; (3) when stock are held in pastures growing this 

 milkweed until all the valuable forage has been eaten; and (4) when 

 stock are bedded on areas where this milkweed is abundant. 



Most plants of a poisonous nature contain substances which are 

 distinctly distasteful to live stock. In general it may be said that an 

 animal will first graze plants to which it has been used and whose 

 flavor has been found agreeable. However, in the absence of good 

 grazing it will eat what it is forced to eat in an effort to satisfy its 

 hunger. It has been found that on certain ranges many plants are 

 eaten which on other ranges are but seldom touched by the same class 

 of live stock. Further, it has been observed that an animal in good 

 flesh will not, when hungry, eat offensive plants as readily as poor 



