4 
Colorado Experiment Station 
The attention of the Colorado Experiment Station was first 
called to this plant in 1915 by Dr. A. P. Drew, of Grand Junction,, 
who reported that he had strong evidence of the poisoning of 
stock from milkweed fed in the hay. Dr. Drew later reported 
that a large percentage of his winter practice is from stock 
poisoning due to this cause. About this time Dr. Walter Craig,, 
a veterinarian at Paonia, also sent in samples of the plant 
and pronounced them as being suspicious. 
Among the cases of large losses that have come to the 
notice of this station in the last few years are the following : 
On Rogers Mesa, near Hotchkiss, Colo., in the fall of 1917, 
44 head of steers belonging to the Bar K Cattle Company were 
lost over night in a pasture. These steers had been driven a 
distance of about 20 miles from the range and were turned into 
the pasture hungry. In the morning 44 head of the animals were 
found dead. Whorled milkweed was ' present in considerable 
quantities and Dr. Craig, of Paoilia, reports that this plant 
was doubtless responsible for the poisoning. 
Near this same place the Bennett brothers, in June, 1918, 
lost 350 head of sheep. The following is taken from Bulletin No. 
246 of this station, page 4. “This case was between Hotchkiss and 
Paonia, Colorado. A herd of 1,700 sheep had been ranged in the cedars 
and sagebrush. On June 2 these were turned into an old, abandoned 10- 
acre orchard for one day for the purpose of shearing and dipping. The 
orchard was enclosed. They were left in the orchard about eight hours,, 
and in the evening driven out of the orchard to their bedding grounds in 
the cedars about 100 yards away. Between that evening and the fol- 
lowing noon 350 sheep died. Inspection of this old orchard was made on 
June 14. It was very thickly grown up to whorled milkweed; in fact, 
there was very little succulent vegetation of any kind in the enclosure ex- 
cept the milkweed. Inspection showed that practically every plant had 
been eaten down, and that that the growth present, was that made be- 
tween the dates June 2 and June 14. The orchard stood in the midst of 
a cedar and sagebrush growth, and examination showed no milkweed 
in this native association. It is clear in this instance that the sheep 
were forced to eat milkweed, and they came there from their range 
hungry.” 
The following case came under the author's observation, 
five miles north of Cortez, Colorado : 
Sheep which were lambing were kept in a dry pen for two 
weeks and were fed on nothing but bright, green alfalfa hay. 
About 9 o’clock on the morning of June 8, a number of these 
sheep with their lambs were taken from one pen and driven about 
75 yards along a bare road to a corral previously unused. The 
sheep were not fed as usual at noon, and the owner did not go to 
the corral until about 4 p. m. At that time 15 of the sheep were 
