cies are available to a deer, and that the ani- 
mal consumes a diet consisting of 30 percent 
black cherry browsed to 2 inches beyond the 
bud (average crude protein content 16 percent, 
fig. 1) and 70 percent red maple. Each 30 
pounds of black cherry would provide 4.8 
pounds of crude protein. To provide 100 
pounds of a mixed cherry-maple diet contain- 
ing 9 percent crude protein, the 70 pounds of 
red maple would have to supply 4.2 pounds of 
crude protein; this would require that its aver- 
age crude protein content be about 6 percent. 
According to figure 2, this could be achieved if 
the deer browsed red maple to a length of 
about 9 inches beyond the bud. 
_. 
-_-~ 
TSS es ao, 
Yj Y ee ene 
— 
CRUDE PROTEIN (PERCENT) 
=) 
1-2 2-3 3-6 6-9 9-12 
TWIG SEGMENT (INCHES) 
FicurRE 1.—Crude protein content of red maple and 
black cherry terminal twigs during the dormant season 
(Camp Run area). Bars represent the mean crude 
protein content of each segment; the line represents 
the weighted mean of whole browse from bud to length 
clipped. The black cherry was in the Camp Run area, 
and the red maple was in the old-field area. 
This is a grossly oversimplified example of 
how only one factor (crude protein content) 
may influence the determination of what the 
deer eats. It is not intended to suggest that the 
deer has a built-in computer that enables him to 
select from his greatly varied “smorgasbord” 
of available foods an accurately balanced com- 
bination of diet ingredients. However, it may 
suggest that a properly planned and coordi- 
nated program of research may result in the 
eventual accumulation of a more-or-less com- 
plete “matrix” of data. Such a matrix may 
cover most of the important deer foods, experi- 
mentally determined feeding “standards” or 
requirements of deer, increased knowledge of 
their eating habits and behavior, factors influ- 
encing availability and utilization of their 
foods, and conceivably a more-or-less “compu- 
terized” solution of forage-management prob- 
lems. It is recognized that the problems are ex- 
ceedingly complex, that they are different for 
each unit of game range, and that precise solu- 
tions and applications will never be possible. 
CRUDE PROTEIN CONTENT OF TWIGS 
The habit of deer in feeding to consume only 
a portion of a plant part is well known. The 
development of a methodology in deer-forage 
evaluation requires knowledge of the nutrient 
content of that portion. But the task of defin- 
ing the portion, or even the plant parts in some 
species, has not been completed for any unit of 
deer range. The difficulty of the task is in- 
creased by the variation that occurs in the size 
or the amount of the portion consumed. An ex- 
ample is twig browse. 
A study‘ was conducted to determine the 
crude protein content of twigs because of the 
possible use of crude protein in a forage evalu- 
ation method. Also, because the portion of 
twigs browsed by deer has not been defined for 
most woody species, there was a special inter- 
est in determining the general pattern of pro- 
tein distribution in twigs. It was also of inter- 
est to compare crude protein content between 
browse species and within species by season, 
structural parts of the plants, and origin of 
plant growth. 
Methods 
Twigs of three native browse species—black 
cherry, red maple, and American beech—were 
collected on the Allegheny National Forest, Pa. 
The sample material was clipped from the cur- 
rent annual growth of unbrowsed plants grow- 
ing under several conditions. All twigs were 
sectioned into various lengths, ovendried at 
105° C., and weighed. 
Twigs were collected from about 20 black 
cherry and red maple seedlings growing under 
similar conditions of treatment in an old field 
area. All were wildlings, 5 feet or less in 
height, that had been transplanted with a 3 by 
3 foot spacing to the old field 6 years pre- 
viously and fenced for a study of the response 
of seedlings to simulated deer browsing. The 
sample material was collected from March 31 
to April 2, during part of the dormant season. 
In another case, black cherry terminal and 
lateral twigs were collected from several 
hundred seedlings, 1 to 4.5 feet in height, 
growing in each of four clearcut blocks in 
widely separated areas. Collection was made 
during the dormant season in January and 
April, and again during the growing season in 
June. Through error, the leaves from the twigs 
collected in the growing season were not saved 
for analysis. The twigs were succulent and 
buds has not yet formed on these seedlings. 
The terminal twigs of sprouts from 30 to 50 
*A cooperative study between the College of Agri- 
culture, The Pennsylvania State University, and the 
Northeastern Forest Experiment Station, Forest Ser- 
vice, USDA. 
51 
