Silage quality is very variable on farms throughout the country. Poor quality silage requires increased concentrate usage to maintain animals, not to mention the requirements for growing animals or those producing milk. In terms of the focus and emphasis we place on making silage, over the last number of years we may have taken our foot off the pedal, with greater focus on grazed grass and less effort going into ensuring we maximise the potential of our silage forage.
When we talk about making quality silage there are a number of factors which can influence the quality of the resultant feed. These can be separated into long term, medium term or short-term factors.
For the 2019 silage harvest, there is not much we can do to rectify the long term factors at this stage; these include ensuring you have the right species in the sward. Perennial ryegrass dominated swards will have superior digestibility, will be relatively straightforward to preserve and are an essential long term investment. Avoiding soil compaction is important as this can reduce yield and persistency of perennial ryegrass. Taking regular soil samples to ensure correct soil pH, Phosphorus (P) and Potassium (K) status is also critical. When selecting mixtures for reseeding silage ground, consider varieties which perform well on the Recommended List and on the Teagasc Pasture Profit Index (PPI) list; AberClyde, AberMagic, Dunluce and AberWolf have excellent performance overall on the PPI list, but also do very well on the silage sub-indices.
When making silage, it is usually the case that as quantity increases, quality decreases. This occurs as the more mature and higher yielding crop will have lower nutrition value compared to a leafier sward. Therefore, there is an inevitable compromise with decisions on when to cut, best determined by the class of livestock to be fed and the stock performance targets, as well as the obvious weather conditions around time of harvest. Keep an eye on the development of the silage crop and monitor to ensure heading date, absence of lodging and the absence of a build-up of dead herbage are progressing as expected. Once heading out commences, the digestibility of the crop will drop by 2-3% units per week. So, if you are aiming to make a high DMD silage you need to harvest the crop just prior to when the seed heads start to emerge, which is about a week before the mean heading date of the varieties in your silage mixture.
Avoid mowing and harvesting under wet conditions. Wilting to achieve an optimum silage DM of 30-35% (pit) and 35-40% (bale) should be ideally, quick and short. This generally requires at least a half a day, and no more than a 1 ½ days of good drying conditions. The best wilt will occur where the grass is mown after the dew has evaporated and is then placed in wide rows or is tedded.
Fill the silo quickly in thin layers, rolling throughout and immediately sealing it perfectly. As the silage sinks somewhat a week or 2 later, adjust the plastic seal to ensure no ingress of air occurs. Inspect the plastic cover frequently and immediately repair any visible damage.