It is commonly thought that rotational grazing results in more pasture dry matter production and as a consequence allows higher stocking rates.
In recent comparisons between set-stocking and rotational grazing in which production was optimised, the stocking rate was 5-15% higher with rotational grazing.
The live weight gain per head was lower under rotational grazing in the prime lamb studies, but there was little or no difference in wool cut per head in trials involving Merino wethers.
In general, when pasture availability is non-limiting, livestock production per head will be higher with set-stocking as it allows animals to select a high quality diet.
However, this may lead to the loss of the most palatable / highest quality species in the pastures so that in the medium- to long-term animal production will decline.
The combination of high stocking rates and set-stocking can lead to an increase in the subterranean clover content, which can also improve performance per head.
In contrast rotational grazing usually leads to an increase in the grass component, which increases production per hectare. Most farmers are likely to see similar or smaller increases in stocking rate with rotational grazing than those measured in research trials unless scale is important.
Large paddocks often contain areas of pasture that are ungrazed or grazed infrequently. If large paddocks are subdivided and rotationally grazed, pasture that was previously under-utilised will be consumed – leading to an increase in production.
A similar result can be obtained by grazing large paddocks with big mobs, thus reducing selective grazing by livestock. During lambing most producers prefer to setstock to reduce mis-mothering particularly with Merino ewes.
However some farmers successfully rotate lambing ewes by allowing them to ‘drift’ between paddocks (i.e. gates are left open so the ewes that have just lambed can catch up to the mob when ready). Set-stocking is also preferred during joining and birth by producers who are single sire mating and who need to identify progeny carefully.
Rotational grazing can be used as a tool to assist in the control of internal parasites, either by using cattle to clean up a pasture for sheep or ensuring that livestock are not exposed to heavy worm larvae pick-up.
This requires planning and an understanding of larval survival patterns. In set-stocked situations clean paddocks can be prepared.
Large mobs associated with rotational grazing can increase the spread of certain diseases (e.g. footrot) or make control difficult. On the other hand, rotational grazing with large mobs can reduce a farmer’s work-load as there are fewer mobs to check and manage compared to set-stocking.
Land degradation:
Deep-rooted summer-active perennials reduce groundwater recharge and subsequent salinisation and can also reduce soil erosion. Most perennial pastures reduce soil erosion to some extent as they increase the surface cover.
However, when lucerne is grazed hard in summer or autumn there is insufficient ground cover (~250 kg DM/ha) to control either wind or water erosion.
Rotational grazing can result in more ground cover than set-stocking and therefore less soil erosion. Set-stocking was compared with an eight paddock rotation at Walebing in the northern agricultural region. The rotationally grazed paddocks had 2 t/ha more ground cover at the start of summer than those that were set-stocked at the same stocking rate (8 DSE/ha).
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