Teagasc Advice for beef farmers: What’s your plan for high quality silage?
On beef farms, making high quality silage will go a long way towards maximising animal thrive in the winter, while controlling concentrate costs.
Farmers who consistently make high quality silage every year do so by following a plan. What’s your plan?
Dry Matter Digestibility (DMD%)
Plan to influence factors that determine the digestibility of silage. The DMD is used as an index of the feed value of forages, the higher the value, the better the feeding value of the forage. Leafy silage has a DMD of 74-76%, compared to stemmy silage (60-65%).
The most important aspect in making quality silage is grass quality at harvesting.
Quality and yield alter rapidly at this time of year. Yield increases, but quality reduces, so a compromise must be reached before quality gets too poor. Young leafy grass will be 70% digestible or more, whereas strong, stemmy grass will be only 60% digestible.
Grazing sward
Graze silage swards tightly down to 4cm before seed heads emerge. This will level off the sward, encourage tillering, while increasing DMD% by 3-4 units. If there are any poached areas, rolling may be necessary in order to reduce soil contamination of mown grass.
Nitrogen
First cut silage requires 80-100 units of N/acre from slurry and fertiliser. Excess nitrogen in grass will inhibit preservation.
A silage crop uses up two units of N per acre per day, in good growing conditions.
Therefore, ensure there are 50 days between nitrogen application and cutting date, to allow full nitrogen uptake by the growing grass crop.
Weeds
Silage yield and digestibility will be reduced if weeds are present in the sward.
Weeds such as docks need to be controlled, before they limit sward productivity.
Spray weeds 3-4 weeks in advance of cutting with a suitable herbicide. This gives time for the weeds to wither away, while allowing the sward to close in.
Time of harvest
On average, grass digestibility decreases by 2-3 units per week in the second-half of May, and June. This decline is due to an increasing proportion of grass composed of stem, as the crop matures, heading to the reproductive phase, with seed heads emerging. Aim to harvest silage crop before stems develop.
Grass sugars
Silage is ideal for harvesting when grass sugars are above 3%. Ideally, cut grass in the afternoon and evening, when sugars are highest. A grass ensilability test can be carried out by your Teagasc adviser or agricultural consultant.
Wilting
Grass cut dry and wilted is easier to preserve than wet grass. Wilting for 24-36 hours increases the sugar concentration and makes it easier to preserve, but this is a major challenge in broken weather conditions. If possible, turn the grass crop twice before you pick it up. Avoid over wilting, mown grass greater than 40% dry matter is hard to preserve.
Pit silage
Fill the pit quickly and roll it well to exclude air. Cover it immediately with two sheets of plastic. Over this, lay a suitable layer of tyres or sand bags. Tighten the plastic on the pit regularly, after covering, to ensure no air gets in.
Baled silage
Round bales should be removed from the field immediately, to prevent crow damage to the plastic. Stack bales on a hardcore base close to the feeding area. Painting has been of little benefit in preventing crow damage.
