Farmer’s Weekly – 02 August 2019

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