OAK-LEAF POISONING OF DOMESTIC ANIMALS. 33 
speaking, those that are injured show the results only after eating a 
considerable quantity through a rather prolonged period. The 
observations on the shinnery oak showed that symptoms resulted 
after the animals had been feeding from 16 to 35 days. 
In the experimental animals, which were fed exclusively upon oak, 
constipation was noted in 2 cases in 6 days, and in the others definite 
symptoms appeared in from 8 to 13 days. In the 2 fatal cases one 
died in 39 days and one in 17 days. Of course, under ordinary 
circumstances, it would not be expected that range animals would 
show symptoms so soon as the subjects of these experiments, for the 
feeding of the animals in the corrals was intensive, and of oak 
exclusively. 
Permanent injury may not follow from oak. Some animals 
injured by oak feeding may linger a long time, and eventually die. 
In some cases, however, favorable conditions may bring about 
recovery with no evidence of permanent injury. No. 704, which was 
the subject of experiment in 1916, was observed through the summer 
of 1917, and made normal gains. 
EFFECT OF EATING OAK WITH OTHER FEEDS. 
The experimental work at the Salina experiment station in 1916, 
1917, and 1918 showed conclusively that oak could be eaten not 
only with no harm but also with apparently distinct benefit if other 
additional forage was provided. As small a quantity as 3 pounds 
of alfalfa hay daily, with the oak, prevented injury and maintained 
the weight of the animals. Range experience in Utah clearly indi- 
cated the same thing. Observations in the handling of cattle on the 
" shinnery" ranges near Monahans, Tex., also demonstrated the 
beneficial effects of comparatively small feedings of hay. 
In this connection it may be mentioned that W. R. Morley, of 
Datil, N. Mex.,"told Assistant Botanist Eggleston that although the 
cattlemen of that region had heavy losses from oak poisoning, he 
himself had avoided them by feeding hay and a small quantity of 
cottonseed meal as long as his cattle returned to the corrals. 
ACTIVE PRINCIPLE OR PRINCIPLES CAUSING OAK-BRUSH POISONING. 
Very little chemical or pharmacological work has been done to 
determine the fundamental cause of the injurious effects of oak-brush 
forage; this matter is still under investigation, but the results are not 
sufficiently definite to report. 
It has been assumed by some that tannin or the tannates might 
be responsible for the trouble. On this account it seemed best to 
perform some experiments with tannic acid. Two animals were used, 
cattle Nos. 755 and 815. It was impossible to estimate the quantity 
of tannin obtained by an animal feeding upon oak brush, for it was 
found impracticable to handle the animals in such a way as to know 
how much oak they were eating. It was planned to give to one 
