Multi-pasture or rotational grazing system where there are more camps than herds of animals.
The grazing area is subdivided into at least one camp more than there are groups of animals and the animal groups are rotated among the camps. Grazing within any one camp is, therefore, intermittent and is more concentrated than continuous grazing. The period of absence from grazing is defined as ‘the period of absence’ rather than as the ‘period of rest’ since it may not be sufficiently long to benefit the grassveld.
Rotational grazing involves a greater concentration of animals than continuous grazing. The primary objectives of rotational grazing are to control the frequency at which plants are grazed, to control the intensity at which the plants are grazed and to reduce the extent to which species are selectively grazed.
Conventional rotational grazing systems include the two-, three-, or four-camp systems which are a slow rotational system, where camps are grazed for a few months on end. Each camp is designed more or less to group the same veld type, which ensures a better management ability.
Disadvantages of rotational grazing:
These are seen relative to continuous grazing
- Higher capital input per hectare in terms of fencing and water points.
- More intensive management and increased management time are required in terms of deciding when to move animals (i.e. with the objectives and type of rotation used).
- Increased labour requirement for moving stock, although it is easier to round up stock for counting, dipping, dosing and inoculation.
- Regular herding and moving of animals from one camp to another, disturb the animals and may affect animal performance.
- Individual animals’ performance may be lower, but production per hectare is usually higher.
- Where cultivated pastures are involved, it is more difficult to establish the pasture and spread fertiliser on smaller camps.
- Where there are many camps, access to camps may pose certain problems.
Advantages of rotational grazing:
Depending on the specific rotational grazing system and the stocking rate applied, rotational grazing systems can have the following advantages:
- Effective rest periods can be applied for many different reasons (eg. seeding rests, rests to improve vigour).
- A higher basal cover can be maintained. This improves soil stability and ensures better and more efficient utilisation of rainfall.
- More effective and efficient utilisation of the available herbage can be achieved by reducing selective grazing.
- The period of utilisation of sourveld can be extended.
- Trampling around water points and the formation of footpaths are reduced.
- Allows for the provision of fodder reserves in the form of ‘reserve camps’.
- Allows for the rationing of herbage during periods of slow growth or drought.
- It is possible to give animals with a higher nutritional requirement preferential treatment.
- Special treatment(s) can be applied to camps which need it.
- Homogeneous areas are camped separately and thus provide for efficient utilisation and maintenance of the natural resources on the farm as a whole.
- Where high levels of nitrogen fertiliser are applied, the possibility of high nitrate-nitrogen in the herbage affecting animal performance is reduced, since the nitrate-nitrogen content in the herbage drops with time.
- It is easier to estimate the correct stocking rate since the veld or pasture(s) is divided into homogeneous units and the estimation of grazing capacity is much more simplified and thus more accurate.
Some factors to consider in rotational grazing
If rotational grazing systems are to be used to advantage, the operator should aim to achieve as many of the following as possible. Note: these factors refer to stable situations and do not involve specialised treatments such as seeding rests, rests for improving vigour, etc.
- Leave sufficient leaf area (when animals are removed) to allow for rapid regrowth. Adjust stocking rate and period of stay.
- Avoid early grazing of regrowth. Adjust the number of camps and/or period of absence.
- Utilise material efficiently by adjusting stocking rate, number of camps and/or the use of a follower herd/flock system.
- Offer herbage at the desired quality for the class of animal. Adjust the number of camps, and period of stay and control the severity of defoliation.
- Reduce leaf loss through senescence: avoid over-accumulation of herbage by adjusting the period of absence. Excess material should be removed.
- Maintain the species composition by controlling the intensity and frequency of defoliation.
- Apply nitrogen when the animals are removed from a camp and thus allow sufficient time for the nitrate-nitrogen level to drop before the next utilisation.
Factors affecting the period of absence in a rotational grazing system
The period of absence in a rotational grazing system is dependent on the period of stay and the number of camps available for each herd. Nevertheless, these must be adjusted to achieve optimum periods of absence for production from the class of animals being grazed in the rotation. The following principle applies: shortening the period of rest will improve herbage quality, but will reduce herbage yield. Within reason, the converse is also true – thus a longer period of absence will result in more herbage of poorer quality.
The exact yield and quality of herbage will depend on the time of the year, the climate and the soil as well as the composition and vigour of the vegetation at each site. For example in veld made up chiefly of sour species, a short period of absence (ie. 30 days) is usual to prevent the veld from becoming unpalatable: with cows in calf (which require higher quality feed) the period may become shorter than for more mature and slower growing steers. Similarly, during periods of rapid growth (with good rains in mid-summer, on fertile soils when plants are in a vigorous condition) the period of absence may be shorter. Sweet veld, because its plants retain their palatability longer, would be given longer periods of absence (50 days).