Making the Most of What we’ve got Left
At the tail end of the growth season making the most of your grass and maintaining pasture quality becomes far more challenging. The aim is to keep grass in the cow’s diet as long as possible whilst maintaining target body condition score.
Supplementation with silage and concentrates needs to be balanced with grass availability in order to leave consistent grazing residuals, whilst still ensuring adequate nutrition. Judging the timing of when to start the final rotation is specific to your farm, typical winter growth rates and grazing system. However, is important to keep in mind that the decisions made in the autumn will affect grazing in the spring, and in challenging years like this it may be better to house earlier and reset for 2025.
Infrastructure
Your farm infrastructure can greatly increase or limit your options and adaptability in the autumn grazing period. Ensuring tracks are in good condition is essential to prevent erosion and lameness in periods of high rainfall. Astroturf can be one option to protect tracks from wear and weathering.
Access points are important for increasing flexibility. More access points will reduce poaching in ‘pinch point’ areas of high cow traffic and enable the use of back-fencing. The same is true for water troughs.
On-off grazing can also help to lengthen the rotation and reduce poaching. This involves grazing cattle when it is relatively dry but housing them and feeding silage in periods of heavy rainfall. Grazing during the day and housing at night is also a popular option.
Grazing
During the late summer and autumn, it is important to walk the grass every week because growth can change dramatically in a short space of time. Knowing what your feed demand is going into autumn and winter will help to dictate where and when supplementation or increased concentrate intake should be used to slow down the rotation. By early autumn, the rotation should be slowed to 30 days to build up covers whilst the grass is still growing, so that the covers are there to meet demand when the growth slows down.
In late summer and early autumn, we want to achieve the balance between maximising grass intakes and ensuring good grazing residuals. It is not easy to get the cows to utilise the grass as effectively during this period, but the aim is to hit residuals of 1500kg DM/ha (4 to 4.5cm) to encourage winter tillering for optimum grass quality in the spring. It also minimises the amount of dead material that will be carried over to the spring grass. Forcing cows to eat higher covers, with grass later than the 3-leaf stage, will reduce utilisation and grass quality, and equally grazing grass before the 2.5- to 3-leaf stage will inhibit autumn growth rates. Grazing residuals of 1500kg DM/ha in late summer will be easier to achieve than in later stages of the rotation, but ultimately updating the feed budget in response to weekly grass growth rates will help you adapt to the conditions by adjusting rotation length or taking bales to remove surpluses.
This year, if wet conditions persist ensure the wetter fields are grazed early to avoid them going into winter with excessive covers. It may be better for some farms to shorten the last rotation from 40 to 30 days and house earlier if ground conditions are becoming the limiting factor.
In the final rotation the fields that are to be grazed first in the spring (60% of the farm), should be grazed and closed first to allow these fields to build up some cover in the tail end of the growth season so that it is able to regenerate effectively in spring. The remaining 40% of the farm can then be used over the subsequent fortnight until the cows are housed. Going into winter with a flat grass wedge, ideally with covers of 2150 to 2200kg DM/ha, will help ensure there is not too much grass going into spring that risks deterioration at the base of sward, reduced quality and requires a high stocking density to keep on top of it.
Summary notes
- Give yourself more options by designing infrastructure to handle grazing in wetter months.
- Aim for residuals of 4 to 4.5cm or 1500kg DM/ha in late summer to reduce dead matter carry over and encourage tillering. It is better to push for target residuals sooner rather than later when conditions become more challenging.
- Use grass growth data, leaf stages, feed budget and ground conditions to determine when to start final rotations and shut up completely for winter.
- Manage supplementation to speed up or slow down the rotation based on your knowledge of your own farm and cow condition.
- Despite the best laid plans, this year rainfall is likely to be the limiting factor so do the best you can and look ahead to the spring.
- AHDB and Teagasc both provide an autumn grazing planner to help plan your final rotation and make sure you are closing off paddocks and hitting peak covers at the right time.
Autumn planning for rotational grazing cattle | AHDB
Autumn Grazing Management – Teagasc | Agriculture and Food Development Authority
Freya Lance, SAC Consulting
This article is part of the September edition of Milk Manager News by the Farm Advisory Service. To read our full publication, visit:
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