The rate at which ewes are grazing swards, hastened by poor grass utilisation, means that most flocks will not have any difficulties in achieving autumn closing targets.
Research carried out in Teagasc Mellows Campus Athenry shows that the aim at a stocking rate of 10 to 12 ewes/ha is to have 20% of the farm closed by late October, 40% by mid-November, 60% by the end of November, 80% by mid-December leaving the final 20% to sustain ewes as long as grass lasts. This is summarised in Table 1.
If these areas are closed in sufficient time, it will generally translate into delivering a similar area of ground available for grazing next spring and in a typical year provide adequate grass reserves to sustain lactating ewes and their lambs until growth rates rise.
A failure to achieve such closing targets will greatly curtail grass supplies next spring.
For an early/mid-March lambing flock, the aim is for an opening farm cover of 600kg to 700kg grass DM/ha or 20 to 25 days grazing ahead. This means that there would be enough grass available to sustain sheep for 20 to 25 days if there was zero grass growth.
As a rule of thumb, swards will need a rest period of 120 days to grow sufficient grass to provide a worthwhile cover next spring. This may be shortened in reseeded or relatively young swards where soil fertility and soil nutrient levels are on target.
This is reflected in Figure 1 which shows the effect of delaying closing paddocks. A closing date of the first week of December taking normal winter grass growth rates will deliver a grass cover in the region of 600kg to 650kg DM/ha next spring.
Taking typical spring grass utilisation such a cover would sustain 100 ewes and their lambs for about four to five days next spring.
If closing the same paddock was delayed for a further two weeks, then the likely cover would fall to just 300kg DM/ha to 400kg DM/ha, or just enough grass to sustain the same 100 ewes and their lambs for a day to a day and a half.
Later closing is likely to leave little to no grass worth talking about until later in the spring.
Swards closed first should be those earmarked for grazing first next spring – typically swards with the best shelter and having the best chance of providing drier underfoot conditions.
Grass growth rates are running slightly above normal but saturated soils and a dip in temperatures will soon bring growth rates well back in line with normal levels.
Reports indicate that some farms have developed quite heavy grass covers on some areas and the challenge as touched on in recent weeks is grazing these areas out in challenging conditions before closing.
An option which may be available to some is switching to grazing lighter covers to hit initial closing targets or taking a quick grazing of heavier covers, then grazing lighter covers to remain on target before returning to graze out the heavier covers again.
Such a scenario will work if it ties in with having the most suitable paddocks available for grazing next spring.
The other option is splitting paddocks and grazing out heavier covers quicker but again this is tricky in current weather.
Given continued high input costs and the labour saving that sufficient spring grass supplies delivers, it is important to keep on top of closing targets.
The financial benefits are clear to be seen by reviewing current grass intake demands.
Ewes will typically be consuming 1.1kg to 1.4kg grass DM per head daily whereas in early lactation a ewe suckling two lambs will require 2.4kg to 2.5kg grass DM in the first four weeks of lactation, rising to 3.2kg to 3.6kg in weeks five to seven of lactation.
Meeting the nutritional demands of ewes with concentrates over grazed grass will cost three to five times more depending on the cost of concentrates next spring leaving aside the labour saved.