|Abstract or Summary
- Land useable for livestock grazing in the western United States is
diminishing because of spreading municipalities, irrigation developments,
highway construction, recreational demands and withdrawals.
Concurrently, the demand for livestock and livestock products is increasing
because of a rapidly growing population. As a result, production
from the grazing land that remains must be increased to
satisfy the increased wants of the population.
Artificial seeding is improving the forage productivity on large
areas of low producing range land in the Intermountain region. Methods
of successfully establishing stands of forage plants by artificial
means are reasonably well understood, but less information is available
about grazing practices that will optimize the returns from these range
A nine-year (1957-1965) grazing study was conducted on a crested
wheatgrass (Agropyron cristatum and A. desertorum) seeding near Malta,
Idaho for the purpose of evaluating plant and animal responses under
three intensities of grazing (light, moderate or heavy) in two seasons
(spring or fall). With the information obtained, suggested grazing practices for optimum livestock production were developed.
Stand density, frequency of occurrence and yield of crested wheatgrass
were not affected appreciably during the nine years by light and
moderate grazing intensities in the spring. Heavy spring grazing,
however, caused a reduction in frequency of occurrence and a lower
yield of crested wheatgrass in the latter years of the study. Intensity
of grazing in the fall season had little effect on stand density,
frequency of occurrence or annual yield of crested wheatgrass.
Initial herbage production in the spring was found to be related
to the amount of residue remaining after grazing in the previous year.
In the heavy spring grazing treatment, each 100 pounds of increased
residue produced an average increase of 64 pounds of initial growth.
Gains per animal, average daily gains and gains per acre were
higher in the spring treatments than in the fall treatments. Average
gain per animal and average daily gains were greatest under light and
least under heavy grazing in both seasons. Average gains per acre,
however, were higher under heavy grazing than light or moderate grazing
in both seasons.
Plant and animal responses indicate that moderate grazing from
early May to late June maintained forage productivity and produced
optimum animal response. Forage was wasted with light spring grazing
and heavy spring grazing caused a decline in plant vigor, forage productivity
and animal response. It was revealed in this study, however,
that vigor and production of heavily grazed crested wheatgrass stands
could be improved by deferment of grazing for a growing season or two.
All intensities of grazing in the fall maintained vigor and production of crested wheatgrass. Gains per animal were slightly less under heavy
fall grazing but gains per acre were slightly more than under light or
moderate grazing in this season.
Information obtained on plant and animal responses indicated that
greater livestock production may be realized if the area to be grazed
is divided into two or more sections. When this is done, grazing can
be alternated between or among the sections in such a way as to allow
maximum opportunity for stand maintenance, forage production and
animal response. The effectiveness of management programs that
developed can be judged by observing the vigor and frequency of
occurrence of crested wheatgrass. Dead centers and fragmentation of
individual plants of crested wheatgrass occur when grazing is excessive
and annual plant species increase in density and frequency. The
fragmentation of crested wheatgrass plants into smaller unite made
density estimates a less sensitive indication of plant response to
grazing than frequency of occurrence. Grazing is abnormally patchy
and coarse unpalatable plants are common when the forage is grazed at
less than capacity.