management differences to
their neighbours, and if grazing
management has any effect on
vegetation, it would be most
evident at these fence lines.
Just to clarify, grazing density,
sometimes referred to as stock
density, is the number of livestock
units per subunit of area (camp)
at any point in time (a day or
a week) on that rangeland. For
instance, two farms may have
the same stocking rate, but
different densities, depending
on the number of camps in
which stock are held per unit
time. Stocking rate is simply
the MLU/ha over the entire
farm for that grazing season.
WHAT WERE YOUR
MAIN FINDINGS?
While it is widely accepted
that planned grazing has
many benefits, the claims that
intensive grazing, including
HPG, increases production
and allows higher stocking
density are unfounded. More
specifically, over 80% of the
fence lines showed no difference
in the number of animals that
can be supported: bare ground,
grass, woody cover or general
plant vigour (greenness). The
lack of vegetation differences
in most cases is especially
meaningful given that grazing
densities were substantially
different across fence lines.
Where high rotational grazing
did affect vegetation cover, it
tended to reduce it. It is unlikely
that there is some critical
threshold of grazing density not
reached by farms in our study,
given that the respondents were
strongly aligned with some of the
most intensive forms of rotational
grazing practices, including
high-density grazing, HPG and
ultra-high-density grazing.
Besides the survey, we tested
theoretical mechanisms that
might underlie vegetation
responses (or a lack thereof)
to grazing management via
an experimental trial. In
this trial, animal behaviour
(grazing patterns, trampling,
dunging, grazing) and weight
gain did not differ between
season-long grazing, four-
camp grazing, or HPG.
TOP:
Researchers
surveyed 48
working farms
to test whether
rotational grazing
sustains higher
animal numbers
while increasing
grass cover and
reducing bare
ground and woody
plant cover.
FW ARCHIVE
ABOVE:
From left: Dr Heidi-
Jayne Hawkins and
Prof Michael Cramer
(supervisors of
the study); and
lead researcher
Dr Zander Venter.
SUPPLIED
2 AUGUST 2019 farmer’sweekly 37
This map indicates the distribution
of the 48 farms that participated in
the online questionnaire survey and
the subset of 14 that were visited for
the fence-line contrast study.
SUPPLIED
Fence-line contrast sites
Surveyed farms
Biomes:
Azonal thicket
Fynbos
Forest
Grassland
Nama Karoo
Succulent Karoo
Savanna