44 BULLETIN 125, U. S. DEPARTMENT OF AGRICULTURE. 



making the drive. If hungry sheep come upon a thick growth of Zyga- 

 denus, some of them, in their haste to satisfy their hunger, are almost 

 certain to become poisoned, while if already well fed they are likely 

 to choose their food with more care and to eat less of the Zygadenus. 



Special care should be used early in the season, not because the 

 plant is more poisonous at that time, but because, on account of the 

 dry condition of other forage, it is more likely to be eaten. Later 

 in the season sheep are less likely to eat a large quantity, because of 

 the greater abundance of other food. As a matter of fact, most of the 

 cases of extensive poisoning have occurred before the flowering of 

 the plant. 



If sheep become poisoned, they should be kept as quiet as possible. 

 Any attempt to make them move about is likely to have disastrous 

 results. 



So far as remedies are concerned, none has been found so far that 

 gives much promise of being really useful. The experimental work 

 at Greycliff shows that repeated doses of tannic acid or sodium 

 bicarbonate will aid in recovery, but this method of treatment is not 

 practically possible for animals upon the range. 



GENERAL SUMMARY. 



Zygadenus grows abundantly on many of the stock ranges of the 

 West and is one of the most important sources of loss to sheepmen. 

 Apparently all species of Zygadenus are poisonous. The plants are 

 poisonous through the whole season of their growth, but the tops are 

 somewhat more poisonous at the time of flowering. The toxicity of 

 the bulbs and tops is about the same, while the seeds are much more 

 toxic than other parts of the plant. Cases of poisoning are more 

 likely to occur before the maturity of the plant, because at that time 

 other forage is scanty. 



The toxic dose varies according to the conditions of feeding. In 

 drenched animals it may be put at about one-half a pound for an 

 animal weighing a hundred pounds. In fed animals it varied from 

 1.6 pounds to 5.6 pounds. 



The poisonous principle is an alkaloid or alkaloids allied to veratrin 

 and cevadin. 



Sheep, cattle, and horses are poisoned by the plant, but the fatali- 

 ties are almost entirely confined to sheep. 



The principal symptoms are salivation, nausea, muscular weakness, 

 coma, and sometimes attacks of dyspnoea. 



To prevent losses, it is important to recognize the plant and avoid 

 grazing upon it. If animals become sick they should be kept quiet, 

 and under this treatment many will recover. There is no satisfac- 

 tory medical remedy. 



