14 BULLETIN 1012, U. S. DEPARTMENT OF AGRICULTURE. 



Efect of method of feeding. Two methods of feeding were used 

 with the experimental animals, forced feeding with the balling gun 

 and feeding the plant mixed with hay. 



Only two sheep, Nos. 564 and 578, were made sick by feeding the 

 plant with hay. They were fed leaves, stems, and buds. The 

 smallest effective dose of leaves, stems, and buds when fed by the 

 balling gun, is 1.096 pounds. The smallest dose of the two animals 

 fed in hay was 0.284 pound in the case of Sheep 564. Apparently 

 the animals fed with hay were made sick on a smaller dosage. There 

 is some doubt, however, in regard to the accuracy of the dosage fig- 

 ures in the case of Sheep 564. Five head of cattle were given the 

 plant in hay, with a minimum dosage of 0.264 pound. 



Influence of age of the plant. It was at first thought that the collec- 

 tions early in the season were somewhat more toxic than those 

 obtained later. A careful examination of the cases, however, does 

 not bear this out. So far as present evidence is concerned, then, 

 the plant is nearly equally toxic at all seasons. 



Comparative toxicity of parts of the plant. An examination of the 

 dosage (Table 1) shows very clearly the extreme toxicity of the seed. 

 The fruit heads stand next, while there is no evidence to show any 

 material difference in the toxicity of the other parts of the plant. 

 It should be stated, however, that of course the weight of seed is of 

 dry material, while the weights of the other parts of the plant are of 

 green material. It would follow, then, that the difference between the 

 toxicity of the seed and the other parts of the plant is not so great 

 as the table indicates. 



Effect on different animals. Only two classes of animals, cattle 

 and sheep, were used in these experiments, and most of the sheep 

 were fed by the balling gun. Comparing Cattle 861 and 863, which 

 received leaves, stems, and young fruit, with Sheep 583, 590, 599, 

 602, and 605, which, were made sick on similar material, it appears 

 that the plant is about twice as toxic for cattle as for sheep. This, 

 if true, is an interesting fact, but probably not of any especial practi- 

 cal importance, as there is no reason to think that cattle on the range 

 eat much of this plant. 



As a general statement regarding the toxicity of Z. paniculatus it 

 would probably be safe to say that, excluding the fruit and the seed, 

 the toxic dose of the plant is between 1 and 2 pounds per hundred- 

 weight of animal. 



Fleming 3 gives as minimum toxic doses for yearling calves three- 

 eighths of a pound, and with regard to sheep states that less than 

 one-fourth of a pound rarely produces poisoning symptoms, and in a. 



3 Annual Report of the Board of Control for the fiscal year ending June 30, 1919. Agricultural Experi- 

 ment Station, University of Nevada, Department of Range Management. 1920, pp. 42-43. 



