34 BULLETIN 767, U. S. DEPARTMENT OF AGRICULTURE. 
animal 25 grams (0.055 pound) and to the other 50 grams (0.11 
pound) daily per 1,000 pounds of animal. 
The 25-gram dose was given to No. 755, being administered by 
drench daily in 3 doses of 8.33 grams each. This was continued from 
August 4 to September 2, producing no effect upon the animal. 
The 50-gram dose was given to No. 815. This, as in the case of 
No. 755, was divided into 3 daily doses, and was continued from 
September 5 to September 10; September 11 only 2 of the doses 
were given, and September 12 only 1. From September 13 to 
September 17 the 3 daily doses were resumed, and on September 
18 and 19 only 1 dose was given. During the experiment the 
animal was fed upon hay. No symptoms were noticed, but on the 
morning of September 20 it was found dead. It was very much 
bloated and it was evident that it had vomited profusely. In the 
autopsy there were found hemorrhages in the trachea. The lungs 
were congested, there were hemorrhages and infiltrations of serum in 
the muscular coats of the esophagus, the first and second stomachs 
were distended with gas, there were hemorrhagic patches in the 
duodenum, and congested spots in the jejunum, ileum, cecum, and 
rectum. There were hemorrhages on the surface and interior of the 
thymus. The superficial blood vessels of the brain were fuller than 
normal and there was a possible excess of spinal fluid. 
The animal had not shown general symptoms which'could be con- 
sidered comparable with oak poisoning, but possibly died from the 
effect of the tannic acid. 
These experiments indicated that the cause of oak-brush poisoning 
could not be tannic acid, and made it very doubtful whether the 
tannin in the oak was the fundamental cause of the trouble. 
SUMMARY OF CONCLUSIONS FROM EXPERIMENTAL WORK- 
• 1. Continuous feeding on oak leaves may produce sickness which 
sometimes has a fatal termination. Only a small percentage of the 
animals in a given range are injured. 
2. The specially marked symptoms are constipation, feces contain- 
ing mucus and blood, emaciation, and edema. 
3. A diet composed exclusively of oak leaves does not form a suffi- 
ciently nutritious diet to permit normal gains in weight. 
4. Oak leaves with a small quantity of other feed may provide a 
maintenance ration. It has been found experimentally that as small 
a quantity of alfalfa hay as 3 pounds daily will supplement the oak 
for this purpose. 
5. Oak leaves may produce injurious effects at any season. Most 
of the cases, however, occur in the spring because on the range at 
that time there is a scarcity of other forage and the young oak leaves 
are attractive. YVnile cattle later in the season may eat largely of 
oak, more or less other forage is available and no harmful results are 
experienced. 
