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



In the two cases of forced feeding of seeds in 1914 the average toxic 

 dose was 0.153 pound; inasmuch as the animal receiving the maxi- 

 mum amount was very sick, the actual toxic limit must be consid- 

 ered to be close to the minimum figure of 0.11 pound. It will be 

 noticed that the cases of feeding of seeds in 1913 had practically the 

 same average dose as the cases of forced feeding in 1914; this is 

 accounted for by the fact that these animals ate the seed in such a 

 short time that the results were similar to those from forced feeding. 



It is interesting to note in Table III that the lethal dose is only 

 slightly larger than the toxic dose. 



In transferring these results to the probable dosage when sheep 

 are range fed, the feeding habits of the sheep must be taken into 

 consideration. In the corrals the sheep do not, as a rule, eat as 

 readily as when on the range. When the sheep in a band are grazing 

 together, both imitation and jealousy affect the quantity of any plant 

 which a sheep eats in a given time; so it is reasonable to suppose 

 that if feed is short and Zygadenus fairly abundant, sheep may eat 

 much more in a short time than they would under corral conditions. 

 Under such circumstances, the dosage might approximate that of 

 the drenching experiments. Therefore, it appears probable that 

 animals feeding on the range might, because of the more rapid eating, 

 be poisoned with much less than when in corrals. 



EXPERIMENTS WITH HORSES AND CATTLE. 



Three experiments were made of feeding Zygadenus to a horse, 

 as shown in Table I (section D), Z. venenosus being used in two tests 

 and Z. elegans in one. The smallest quantity fed in these experi- 

 ments was 12.1 pounds per 1,000 pounds of weight, and the largest 

 was 15 pounds. In each instance the feeding was extended through 

 several days, and the feeding of 15 pounds extended through 6 days. 

 If the quantity necessary to poison a horse should be in the same 

 proportion to its weight as that required to poison a sheep, it would 

 be, according to our dosage, at least between 11 and 12 pounds, and 

 probably much more. It may be presumed, therefore, that in these 

 cases the amount fed was not sufficient to produce toxic effects. 

 There is, however, abundance of evidence that horses are poisoned 

 by Zygadenus, although not ordinarily with fatal results. 



Section C of Table I shows the results of feeding Zygadenus 

 venenosus to three cattle. Two of these animals, both of which 

 received leaves and flowers, showed symptoms of poisoning, one 

 on 58 pounds per 1,000 pounds of weight and the other on 46.5 

 pounds per 1,000 pounds of weight. In these cattle, therefore, 

 the average toxic dose was 52.25 pounds, which was fed in an average 

 of 6 days. This compares fairly well with the results reached with 



