An article on last week’s sheep page highlighted the importance of maximising performance from grazed grass.

This week’s feature goes into much more detail on exactly how to set the farm up, how to budget grass supplies and steps that should be taken to keep grass quality to the fore.

It utilises the latest research from Teagasc and includes experience from the Teagasc BETTER Farm sheep programme.

Farm variation

The first point to note is that there is a big variation between grass supplies and growth rates on farms.

Farms which applied fertiliser in late February or early March and started the grazing season with a strong grass supply have seen growth take off in the last 10 days and recorded growth rates of 30kg DM/ha to 50kg DM/ha over the last week or even higher on paddocks with strong covers.

Growth rates recorded on these farms is in the region of 15kg DM/ha to 30kg DM/ha

This is in contrast to farms who only got fertiliser applied in late March or early April and which are located in exposed areas where growth is generally slower to increase.

Growth rates recorded on these farms is in the region of 15kg DM/ha to 30kg DM/ha, which is a significant increase from low single digit growth a fortnight ago.

Teagasc sheep specialist Ciaran Lynch says the two situations are quickly apparent in growth rates recorded on PastureBase Ireland.

While this gives rise to slight differences in management, the advice for farmers is generally the same – don’t panic and try to take advantage of the current increase in temperatures and growth rates.

Tailor group sizes

If not already complete, the first step to managing grass is to batch ewes and lambs into larger grazing groups.

Ciaran says that field size or paddock size is often not the limitation in grouping animals into larger groups with farmers sometimes cautious due to concerns of lambs being too young to group together and being able to handle higher numbers in handling facilities.

The benefits of this approach far outweigh the negatives

He points out that the number of times significant tasks will be carried out between now and weaning is small and says that many of the farmers operating in the BETTER Farm programme have moved to increasing group size earlier in the season and become accustomed to handling larger batches. The benefits of this approach far outweigh the negatives.

This will benefit farms tight on grass

“Reducing the number of grazing groups will allow you to clean out paddocks faster, ewes are spending less time grazing low covers and a reduced area of ground is being grazed at any one time, which will maximise growth rates over the entire farm. This will benefit farms tight on grass as well and for those with more plentiful supplies it gives a better opportunity to drop areas out of the grazing rotation during peak growth.”

Ewe demand peaks at six or seven weeks coinciding with peak milk yield

Determining the optimum size of grazing groups needs to take account of paddock/field size and satisfying demand for grass. Table 1 details the typical grass demand of ewes and lambs during the grazing season. Ewe demand peaks at six or seven weeks coinciding with peak milk yield.

Table 2 details the typical volume of grass dry matter present in one hectare at varying grass heights.

The optimum early in the season is turning animals into a pre-grazing height of 7cm to 9cm and removing them at 4cm. The post-grazing sward height increases as the season progresses.

A 100-ewe flock

The experience from the work undertaken by Philip Creighton in the research demonstration flock trial in Mellows Campus Athenry shows that for a flock of 100 ewes stocked at 10 ewes/ha the advice is five permanent divisions of 2ha in size (five acres).

The target is to have the flexibility to subdivide each of these during peak growth with temporary fencing to give 10 divisions.

Increasing to a six-paddock rotational grazing system with paddocks pf 1.6ha (four acres) will bring further benefits in increasing grass production and utilisation by in the region of 15%.

Getting back to current grazing management, Ciaran says that farms with heavy covers in the region of 2,000kg DM/ha should not be afraid to drop these out of the rotation and save as baled silage in the coming weeks. This will deliver two-fold in delivering a supply of excellent quality silage and bringing top-quality grass regrowth back into the rotation.

This will also help animal performance

Where heavy paddocks have to be grazed, utilisation can be significantly increased by splitting paddocks.

This will also help animal performance as there will be a shorter window where they are forced to graze down lower-quality grass.

It will become a greater issue as we advance into May and Ciaran is advising farmers to set up systems to utilise temporary division of paddocks in advance of when they will be required.

For some farmers with strong grass supplies, there may be a temptation to refrain from applying fertiliser.

This approach early in the season can lead to potential grass shortages down the line.

There will be serious demand for grass for most farms

“We have seen an increase in growth rates recently but this can change and we have seen in recent years that growth rates are often under pressure well into May. There will be serious demand for grass for most farms at the end of April or at the start of May as ewes hit peak intake and lamb intake jumps. Therefore, we need to keep the foot down to capitalise on this growth and apply fertiliser after each grazing,” Ciaran says.

The general recommendation is 20 to 25 units of nitrogen. Ciaran says farms with good soil fertility are continuing to apply protected urea while others are switching to compound fertilisers from now on where there are any known soil fertility deficits.

Ideal time for a review

Farmers who are measuring grass are best placed to determine how grass supplies are performing and if changes need to be made. Table 3 details targets in terms of cover per livestock unit and the ideal number of grazing days ahead.

Even where grass is not being measured farmers should still walk their farm and assess how they are fixed.

It is also a good time for farmers to critically assess if they need to make changes to their system

As a rule of thumb, Ciaran says for early-to-mid March lambing flocks the target is to have 60% of the farm grazed by the start of April and the second rotation starting in mid-April.

It is also a good time for farmers to critically assess if they need to make changes to their system such as closing up earlier in autumn to have grass supplies in spring or tweaking the lambing date to better match grass supplies and growth in spring.