Air-free conditions necessary for good preservation
It requires at least a half day, and not more than 1.5 days of good drying conditions.
Fill the silo quickly, rolling the herbage throughout, and immediately seal it perfectly. This will help to achieve the air-free conditions that are necessary for good preservation, and to prevent mould growth.
For pit silos, seal immediately and properly beneath two sheets of black 0.125mm polythene. Cover completely with a layer of car tyres, etc, placed edge-to-edge, and seal the edges with a layer of sandbags, silt.
As the silage sinks somewhat into the silo during the following week or two, check the plastic seal to ensure no air gets in.
Inspect regularly and re-pair damage or looseness in the plastic.
Here is Padraig O’Kiely’s questions and answers on grass silage from the current issue of the Teagasc magazine, Todays Farm.
>> If your aim is to achieve high yields of easy-to-pre-serve silage, perennial rye-grass dominated swards are an essential long-term investment.
Permanent, perennial rye-grass crops, properly managed, are the foundation of a long-term strategy for the more predictable and consistent production of high yields of cost-competitive, quality silage.
For all silages, ryegrass swards are considerably easier to preserve than pastures containing little ryegrass.
>> For first-cut silage, apply up to 125kg of N/ha, between the combined contributions of inorganic fertiliser and slurry.
Excess or late application of N from inorganic fertiliser and/or slurry can seriously reduce grass sugar concentration and increase buffering capacity, thus making the grass harder to preserve. Similarly, late or uneven application of slurry that leaves the grass contaminated at harvest time inoculates the grass with undesirable bacteria, making the silage more difficult to preserve.
>> Harvest at the right growth stage. Leafy grass will make silage of high feeding value. Grass harvested when stem-my will produce silage of only low to moderate feed value.
>> Excellent preservation means the silage retains the feeding value of the grass from which it was made. Poor silage preservation means the feed value will decline during ensilage in pits or bales. Silage feeding value will also be influenced by the amount of effluent lost and by any heating that occurs during feed-out.
>> The grass must be quick-ly sealed within a pit or bale so that it has no further contact with air.
This prevents all deterioration and rotting processes that require air.
The grass must quickly undergo a fermentation that will limit or prevent protein breakdown. This fermentation is brought about by lactic acid bacteria naturally present on the grass converting grass sugars to lactic acid.
>> Grass in Ireland normally has adequate lactic acid bacteria, but avoid contamination of grass with soil or manure, as this can cause harmful bacteria to dominate instead.
Most crops do not require an additive to be applied at harvesting. This is particularly true for wilted or stemmy herbage, or herbage with an adequate sugar content.
The content of sugar varies widely in grass, and adequate sugars result in production of sufficient lactic acid to deliver a satisfactory decline in pH.
Overall, the extent of fermentation required, and thus the requirement for sugar to ferment, gets smaller as the grass is harvested at progressively more advanced stages of wilting (progressively drier).
If an additive is applied to leafy, wet crops of low sugar content, it is important to know the ensilability of the crop (eg, by measuring its level of sugars with a refractometer), its yield (weigh strips of grass) or harvest rate, and the rate of additive to be applied.
Additives such as beet pulp or citrus pulp, molasses or acid-based products, when evenly applied at appropriate rates, are most effective under ‘low sugar’ conditions.
If a bacterial inoculant is applied, a production response is more likely with crops of adequate sugar content.
