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BULLETIN 365, LT. S. DEPARTMENT OP AGEICULTUEE. 





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Fig. 10. — Chart of feeding of DelpMnium harheiji to cattle 

 experimentally poisoned in 1909 based on weekly aver- 

 ages. The weights of plant are given per thousand 

 pounds of animal. 



toxicity plays a more important part in those years. The average 

 toxic dose for 1 day's feeding in 1910 was 54.9 pounds, and in 1911 

 it was 69.5 pounds. It thus appears that, in the general average of 



cases, cattle weighing 

 1,000 pounds will be 

 poisoned if they eat 

 as much as 60 pounds 

 in one day. This 

 quantity varies, how- 

 ever, within wide 

 limits, in one case 

 being as low as 30 

 pounds, and at the 

 other extreme as 

 high as 93.3 pounds. 

 A tabulation of 

 the quantities eaten 

 the first day by ani- 

 mals poisoned in 2, 

 3, or 4 days shows that few exceeded the toxic limit; of 15 cases 

 in 1909, No. 115 ate 37 pounds, No. 98 ate 58.16 pounds, and No. 112 

 ate 56.5 pounds. Of 15 cases in 1910, No. 612 ate 43 pounds, No. 610 

 ate 36 pounds, and 

 No. 121 ate 38 

 pounds, while in 

 1911, of 6 cases. No. 

 639 ate 62.2 pounds 

 and No. 647 ate 46 

 pounds. It will be 

 noticed that only one 

 of these exceeded the 

 average quantity 

 which poisons in 1 

 day's feeding, but 

 that all exceeded the 

 minimum. 



While some of the 

 differences in the 

 toxic dose can be ex- 

 plained by seasonal 

 differences in the plants and the duration of feeding, many remained 

 unexplained. These differences, under apparently the same condi- 

 tions, are shown in cases 637, 646, 639, 647, and 640 of 1911. All these 

 animals were fed between July 25 and July 31, with the following 



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Fig. 11. — Chart of feeding of Delphinium barbeyi to cat- 

 tle experimentally poisoned in 1910 based on weekly 

 averages. The weights of plant are given per thou- 

 sand pounds of animal. 



