To ensure that you can provide your animals with high quality, nutritious forage throughout the year, it is necessary to preserve the harvested basic ration. Silage is a method that preserves nutrients well and at the same time is efficient in terms of production costs.
Preservation with lactic acid fermentation
The plants are covered in various microorganisms, including lactic acid bacteria. In the absence of air, these convert part of the sugar in the plants into lactic acid. The acid formed leads to a rapid reduction in pH value and keeps the forage stable from a microbiological point of view. The forage can now be stored.
However, there are companions to the lactic acid bacteria on forage crops can cause problems during the silage making process.
Undesirable microorganisms
Clostridia are among the biggest enemies of lactic acid bacteria. They convert sugar, protein and lactic acid into butyric acid, which is not good. Clostridia are found in the soil and therefore enter the silage primarily as a result of dirt ingress during harvesting.
Coli bacteria predominantly produce pungent smelling acetic acids. Putrefactive bacteria decompose high-quality protein. These bacteria enter the equation as a result of contaminated forage.
Yeast and mould can form as a result, causing unwanted reheating.
Competitive advantage for lactic acid bacteria
All of these microorganisms are in strong competition with each other. The big advantage is that they have different requirements to thrive. The way to get the best silage is therefore to give the lactic acid bacteria a clear competitive advantage right from the start by immediately sealing off the air supply and rapidly lowering the pH value.
When it comes to the best silage making conditions, avoiding contamination due to dirt ingress is one of the top priorities. This prevents many of the unwanted microorganisms from entering the silage in the first place.
Another major influence on successful ensiling is the botanical composition of the crop. Crops with a high proportion of grasses are very suitable for making silage. This is because grasses contain high sugar levels compared to legumes and herbs and therefore provide plenty of nutrients for lactic acid bacteria. In addition, the content of protein compounds and minerals with a buffering effect is lower, which can promote rapid drop in the pH value.
But the timing of the cut also plays a major role. The crude fibre content must not be too high, otherwise it is difficult to compact the forage well. Compaction completely expels any air left in the crop from the clamp.
The ideal conditions for optimum silage making is a dry matter content of 30-40%.
Up to 28% DM, fermentation juices form and incur considerable dry matter losses during ensiling. At the same time, there is an increased risk of butyric and acetic acids forming in forage that is too wet.
Above 40% DM, on the other hand, the forage is more difficult to compact and it becomes too dry for the lactic acid bacteria. Fungi can form as a result of yeast and mould activity.
In addition, the DM content must be the same throughout the forage. For optimum silage making conditions, the fluctuations throughout the entire crop should not exceed +/- 5 percentage points.1 This requires a clean and tidy spread pattern by the tedder and precise placement by the conditioner.
1 Resch, R. (2017): Gärfutterqualitäten Wo stecken die Reserven? 44. Viehwirtschaftliche Fachtagung 2017, 81-93.
The chop length is a compromise between ruminant-friendly feed and suitability for compaction.
The shorter the material, the better it can be compacted. At the same time, if the forage is too short, the plant structure necessary for the ruminant is lost. For sufficient rumination activity, the particle length should not be less than 22 mm.
To avoid the cows being selective at the feed barrier, the particle length must be uniform. Consistent chop length is therefore crucial. This keeps particles that are too long to a minimum, significantly increases the compactibility of the silage, and prevents the cows from being selective. In forage management terms, the principle should always be: As short as necessary, as long as possible.