Successful implementation of any spring grazing plan requires managing wet conditions over the calving period.
The aim is to minimise pasture treading and pugging and increase pasture regrowth and long-term persistence.
Occasionally, dry conditions occur during the calving period, such as in spring 2013, when conditions were so favourable they created high pasture covers, which also threatened to reduce the tillering the pastures depended on to persist and thrive. However, normally, wet soil is the problem.
TREADING DAMAGE REDUCES PASTURE REGROWTH
On-farm trials have found that treading damage can reduce pasture regrowth from 15-60 per cent, depending on soil type, weather conditions and grazing management.
The least amount of damage to pasture regrowth from grazing (15 per cent loss) occurred on free-draining soils and was the result of daily on-off grazing, which occurred regardless of weather conditions.
Even this lowest loss of pasture recorded had an estimated value of $90/ha if the feed had to be replaced. This suggests valuable feed can be created on many farms by having a plan to reduce treading damage while maintaining an adequate rotation length at the same time.
OPTIONS FOR REDUCING TREADING DAMAGE
Stick to the planned area allocation for that day and withdraw the cows after a grazing period of four hours for dry cows, or eight hours for milking cows. This is known as standing-off, on-off grazing or duration-controlled grazing.
It is better to provide milking cows with two, four-hour allocations than a single eight-hour allocation. Research has shown that milking cows can eat approximately 80 per cent of their daily dietary requirements in two four-hour periods.
Cows grazing for a four-hour period when soil moisture is high minimises the extent of soil treading damage and protects pasture regrowth.
Through using this technique, damage to pasture regrowth can be further reduced by avoiding walking cows across pasture that has already been grazed.
Using a back-fence on each fresh break during wet periods will also help prevent previously undamaged, or partially damaged, soils from becoming trampled.
Increase grazing area
During wet periods, allocate a greater area for grazing to decrease stocking density, increase pasture grazing residuals and reduce cow movement by keeping cows well fed and content. The risk here is that the length of time before dry grazing conditions return is unknown.
A much greater area of the farm could be grazed than planned, resulting in faster rotation. Areas could be left with higher than expected grazing residuals, which may reduce subsequent pasture quality and tillering. To cope with this, develop grazing plans that allow for spare pasture cover which means more area can be offered during wet conditions.