Managing current grass deficits

Many parts of Leinster have large soil moisture deficits and compromised grass growth. Even if the soil moisture deficit is corrected in the very near future, it will be weeks before normal grass cover can be built.

• Glanbia survey shows a grass growth range of 20-80 Kgs DM/ha/day
• Today’s PastureBase Ireland data shows a range of average growth in counties within the GI region of 45-68 kg DM/ha/day. Leinster has an average growth rate over the past seven days of 49 kg DM/ha/day, approximately 18.5% behind average growth rates achieved in Munster.
• Met Eireann soil moisture deficits (SMD) are as high as 70mm currently and predicted to worsen by 15mm in the current week.
• Against that back drop growth will reduce further and when growth falls below 50Kgs DM/Ha with average stocking rates a deficit is escalating.
• At this point early intervention will minimise the economic impact.

Grassland Management advice:

• Walk all paddocks regularly to assess grass availability & make timely decisions.
• Extend the rotation length to 24-25 days (adjust based on growth/demand relationship).
• Maintain a minimum farm cover 500 kg DM/ha.
• If demand exceeds growth, the deficit will grow. To decrease demand:
  • Bring back in uncut silage ground into the rotation if cover is <2500kg DM/ha. Strip-graze to achieve good utilisation
  • Prioritise lactating cows over dry stock and young stock as alternative diets can be used.
• Maintain post grazing residuals of 4 cm. Over grazing will impede recovery especially in dry conditions.
• Maintain fertilizer N applications while farm is still green.
• Where slurry is not applied or delayed it is important to use P & K with nitrogen.

Farm Example (100 cow herd, current stocking rate 3.1 cows/grazing ha)

• To prevent deterioration in average farm cover and stretch the rotation to 25 days, we can only allocate 1.28 ha/day.
• To bridge the current gap we need to feed 7 Kgs of DM (of concentrate/straights/silage). Two options to fill the gap are outlined below:

• When grass availability falls 60% or less of dry matter intake, a good source of long fibre is critical to sustain milk solids and rumen function. The most ideal product for this purpose is Alfalfa. A limited quantity of Alfalfa is available and farmers that need the product should engage with their Glanbia representative as early as possible

Practical Considerations:

• Buffer feeding that includes a forage is critical once grass DM intake approach 50% of total DMI
• The availability of barrier space and mixing equipment is required when buffer feeds are essential.
• Early intervention with concentrates/straights is the simplest approach and will reduce the need for more drastic interventions later.
• If in doubt – seek advice!

If severe deficit situations consider confining dry stock and using a combination of silage, concentrates/straight to preserve grass for high priority stock.

For more information and advice on farm specific scenarios, contact your local Glanbia Ireland representative.

First Published 26 May 2020