This week’s frost is the first sign of traditional autumnal weather, with temperatures previous to this running well above average, while rainfall levels have also been much lower.
This has given rise to significantly higher grass growth rates in recent months, with growth in October and November especially benefitting. As such, grass supplies on many farms are in a much better position than anticipated.
Farms that experienced drought conditions during the summer should have enough grass to sustain ewes outdoors until their normal housing date, while many other farms are in a much better position and should achieve a significantly longer grazing season.
The higher than normal growth rates have seen a significant cover of grass develop on paddocks closed first in mid-October for grazing next spring. This is raising questions as to whether it is better to regraze these areas, with a temptation to utilise grass now where supplies appear good.
The drop in temperatures will serve to significantly slow down growth rates
The answer to this question will depend on the height of the sward at present, the cover of grass on other swards, lambing date and stocking rate.
The drop in temperatures will serve to significantly slow down growth rates, so care needs to be taken when deciding on whether or not to graze closed paddocks, as it will be challenging to build any worthwhile covers from now on.
For swards with a grass height of 7cm to 9cm (cover of 1,000kg to 1,500kg DM/ha), quality will generally hold ok over the winter for grazing in March 2022, with growth likely to be negligible from then on.
Some farmers in such a scenario have opted to close other paddocks in recent weeks
Where swards have a heavier cover than this, they now may become an issue while also slowing down spring growth, especially if grass growth rates remain above normal.
Some farmers in such a scenario have opted to close other paddocks in recent weeks, which have greened up nicely and developed a good cover of grass, meaning they will still remain on target to have sufficient grass available next spring.
This is not an option for everyone and also has to tie in to the replacement paddock’s proximity to the yard, shelter available for grazing first, etc.
Given where fertiliser and concentrate prices are forecast to be next spring, I would be erring on the side of caution and be much happier to be closing at higher than target covers than knowingly walking into a grass deficit.
The value of the additional grazing now will only be a fraction of the value that it will offer next spring and, as such, it is vital that you remain on target with closing dates.
Teagasc has undertaken a lot of work in this area in recent years, through experience with its research flocks in Mellows Campus Athenry and also through the experience of participants in the BETTER Farm sheep programme.
Its advice for a mid-season March lambing flock with a stocking rate of 10 to 12 ewes/ha is to have 20% of the farm closed by mid-October, 40% by mid-November, 60% by the end of November and 80% by mid-December, leaving the final 20% to sustain ewes as long as grass lasts.
Failing to hit these closing targets will have a detrimental effect on grass supplies next spring
This will translate to having a similar area of ground coming on stream as required next spring and, in a typical year, will provide a sufficient reserve of grass to sustain ewes and lambs until growth rates kick in.
Failing to hit these closing targets will have a detrimental effect on grass supplies next spring. This is reflected in Figure 1, which shows the effect of closing date on grass supply in early April.
A closing date of the first week of December will, in normal growing conditions, deliver a grass cover of 600kg to 650kg DM/ha next April. This will provide grazing for about 100 ewes and their lambs for about four to five days in spring.
If closing was delayed in the same paddock for two weeks, there is likely to only be a cover of between 300kg and 400kg DM/ha or enough grass to sustain the same 100-ewe flock for a day to a day and a half. Close any later than this and there is likely to be no grass worth talking about available until well into next year.
The financial upshot of adhering to target closing dates can be teased out by looking at current intake demands and demands of ewes in early lactation. At present, a ewe will typically be consuming 1.1kg to 1.4kg dry matter per head daily.
Contrast this to early lactation, where ewe-suckling twin lambs will require 2.4kg to 2.5kg grass dry matter in the first four weeks of lactation, rising to 3.2kg to 3.6kg grass dry matter in weeks five to seven of lactation and the value of saved grass quickly becomes apparent.
Meeting the nutritional demands of ewes from concentrates over grazed grass will cost four to five times more with a 100-ewe flock capable of accumulating concentrate feed costs well in excess of €100 per day.
This does not take into account the potential benefit that having sufficient grass supplies available next spring may have in reducing the pressure to apply chemical fertiliser.
It is worth pointing out that it will not eliminate the need for fertiliser, but it may leave the farm less exposed at a time of peak demand, or if there are challenges in sourcing the farm’s normal spring nitrogen requirement.