Improve your silage quality - and feel the benefit in liveweight gains
Grass silage accounts for 20-25pc of total annual feed per cow on well-run dairy farms and up to 30pc of total feed on beef farms depending on the production systems in place, figures from Teagasc show.
Over 85pc of farms in Ireland make silage each year, and the estimated cost of harvesting over 1m ha of grass silage exceeds €500m annually.
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However, based on surveys of silage analysis results conducted by Teagasc over recent seasons, it is clear that silage quality on beef farms also needs to be addressed.
Mean silage quality on beef farms sits at 66 DMD, which is adequate for dry suckler cows in good body condition but is a low-grade feed for growing and finishing cattle.
Clearly this is a significant cost, so making the best-quality silage possible must be a priority for farmers.
Teagasc research has found that grass silage costs approximately 2.0 to 2.5 times more than grazed grass per tonne of dry matter fed.
Most of the additional cost is incurred through harvesting and fixed charges, plus feed-out costs.
Dry matter yield is the most important factor affecting cost per tonne of silage fed.
Over a number of studies at Teagasc Grange, leafy silage with higher dry matter digestibility (DMD) resulted in better feed intakes and liveweight gains for finishing cattle.
Cutting date impact on quality
High yield for first-cut silage reduces cost per tonne in the pit.
However, it has been shown that silage quality (DMD) falls rapidly after grass heading date (0.5 units per day).
For high DMD, farmers should mow their crops as seed heads begin to emerge, for standard DMD mow six days later.
Impact of soil fertility
Teagasc soil testing results have indicated that soil P & K concentrations as well as pH (lime requirement) have been depleted in recent years.
This is reflected in sub-optimal grass growth and consequently light yields at target harvest dates.
The consequence of this is later cutting dates to maximise yields which results in poorer quality silage.
It is imperative that soil fertility is optimised and the correct fertiliser regime is applied to allow farmers to achieve target silage quality:
- Good soil fertility = target yield 5t DM reached by May 26 = good-quality silage (72 DMD)
- Poor soil fertility = target yield 5t DM reached by June 16 = poor-quality silage (62 DMD)
- Swards on high-fertility soils have earlier recovery and three weeks more growth for the second cut.
How do wilting duration and swath treatment affect DM?
The change to grass dry matter content due to wilting is affected by duration of wilt and mechanical treatment of the swath.
Dry matter of grass cut into large rows will change little in a 48-hour period.
However, tedded swaths wilted for greater than 24 hours may become excessively dry.
Essential steps for better silage bales
- Mow when dew has evaporated and wilt to a target of 30 to 35pc DM
- The aim is for dense, well-shaped bales with over 220kg DM per bale. Baler choppers increase DM per bale by 10-15pc.
- Use a slow tractor speed to produce well-packed bales. Adjust the baler density setting to a high/maximum position.
- Avoid rough handling of unwrapped bales as this can cause them to lose shape. A bale lifter is preferable.
- Use a recommended plastic wrap sourced from a reputable supplier.
- At least four layers of plastic are required for adequate preservation. Under good management conditions the benefits of six layers is small.
- If bales are to be stored for a prolonged period (nine months+) then six layers is advised.
- Ideally transport bales to final storage area before wrapping. Damage to wrap during transport is a significant source of DM loss.
- Bales made from low DM or very leafy grass will lose shape when stacked, increasing spoilage losses. Store on ground level instead.
- Check for damage and repair plastic on a regular basis.
- Aim to have bales consumed within two days at feed-out. Do not feed mouldy bales or parts of bales to livestock.
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