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Autumn Grassland management for sheep

As we move into late August attention must now turn to managing grass to maintain finishing lamb performance, getting ewes into adequate condition prior to mating and planning for grass for next spring. Researcher Philip Creighton gives some advice and guidance.

Grass growth rates have been strong for much of the country over the past month or 6 weeks averaging 60-70 kg DM/ha/day in many cases. This has resulted in a lot of grass building up on farms with day’s ahead figures of 30 days ahead not uncommon. This has presented its own challenges with pre grazing covers getting strong at times (>1800kg DM/ha) with the added complication of very wet conditions in most parts of the country making utilisation difficult.

It is important to assess grass availability and quality to try and maintain animal performance. Where weather conditions allow it is not too late to remove some of the heaviest covers as baled silage to get pre grazing covers back on target (1200-1500kg DM/ha 7-9cm).  

A leader follower system should be used allowing the lambs access to the best quality grass grazing down to around 6cm with ewes then grazing swards out to 4-4.5cm. Target days ahead figures for the autumn period are presented in table 1.  Where grass covers are higher than desired and the option to remove as silage is not available subdivision of these stronger covers to increase grazing pressure should be considered to try and clean out paddocks as best as possible. Strategic topping to clean out these stronger paddocks fully after grazing can also be considered.

Identify fields to be closed

It is important at this stage to identify what fields will be closed first and in what sequence in October and November to plan for adequate spring grass supplies. Grazing these fields out properly now will make it easier to graze these fields out in the final rotations and will improve the quality of grass carried over winter and into early spring. An option to increase grazing pressure to get through stronger covers quicker could be to go through the ewe flock and pull out thinner ewes that would benefit from some preferential treatment and put these in with lambs.

With the strong grass growths experienced less fertiliser has been spread in many cases. It will be important over the coming weeks to ensure swards receive some level of Nitrogen application to allow grass to continue to grow into the autumn. Higher stocked farms (>10 ewes/ha) should be applying up to 30 kg N/ha (~25 units/ac) while lower stocked farms (<10 ewes/ha) should apply up to 20 kg N/ha (~15 units/ac).

Table 1. Suggested Sheep grazing targets for autumn/early winter

 Pre-grazing yield 
(kg DM/ha)
Target days ahead Rotation length
August 1250-1500
15–20 days 25-30 days
September 1500-2000
25–30 days 25-30 days
October/November/December <2000
30–40 days Closing paddocks from 20th October