How can good grassland management in autumn affect silage quality next year?

Producing high dry matter digestibility (DMD) silage is the objective on dairy farms across the country and good grazing management in autumn and spring has an important role to play when it comes to achieving this task.

The recent good grazing conditions have been welcomed by farmers. It has allowed paddocks to be grazed to the desired residual, without causing any damage to the sward.

The quality of the silage will depend on harvest date and growth stage at harvest. In addition, leafy grass has much higher DMD value than stemmy grass.

According to Teagasc, grazing down to a residual of 5cm – in late autumn or early spring – is the key to ensuring that re-growth is of a high DMD value.

If a good clean out is not achieved, this can lead to dead vegetation accumulating and – therefore – the quality of the sward will be reduced significantly.

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Although weather conditions are favourable at the moment, if the weather takes a turn for the worse, damage to the sward – through poaching – should be avoided; this will have negative effects on yield and quality.

Weather conditions can make grazing difficult and the desirable height a challenging target to hit during early spring.

On some farms, it may be an option to graze fields earmarked for silage now, instead of in early spring.

Grazing

Research from Teagasc has shown that fields ungrazed in late autumn and early spring will produce lower DMD silage compared to those that were grazed.

Grass digestibility (DMD%) for a first-cut harvest on May 18, depending on previous management (average of two years results). Source: Teagasc

Un-grazed grass – in late autumn or early spring – that is harvested for silage in late May will have an estimated DMD of 75%.

In comparison, when grass is grazed to 5cm in autumn only and harvested in late May, this silage is estimated to have a DMD value of 82%.

However, there was no difference in silage DMD if grass was grazed in autumn compared to spring and harvested in late may.

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