Quality silage in the field is dependent on many factors, including the weather conditions, time of day, and height of the cut. Good dry matter and sufficient soluble carbohydrate content both contribute to good silage in the field, with the D-value and correct chop length also being important considerations.
There are many conditions which should be taken into consideration when looking for good silage; it’s important to cut the grass when it contains the highest nutrient levels.
Cutting Date and Time
Silage is a compromise between the quantity and quality of grass. Generally, as the bulk increases, the quality decreases as stems and seed heads become difficult to digest. The grass should be cut before the sward becomes stemmy and lignifies. However, this can be difficult to achieve in poorly managed swards, as there can often be a large variety of species with different heading dates.
However, the best date for cutting is dependent on the type of stock which is being fed. While high-yielding dairy cows require high ME, quality silage, beef cattle and sheep may need a lower level of ME.
Sugar drives the fermentation process as grass with high sugar levels will quickly ferment and reach a stable pH. In grass, sugar is found in the form of a soluble carbohydrate, the content of which is at its highest on sunny days when the crop has been photosynthesising.
It’s important to ensure that excess nitrogen isn’t applied close to the cutting date of the grass as it can reduce the soluble carbohydrate content and result in poor fermentation.
When grass is cut when it’s wet or heavily rained on, the silage will have a lower dry matter. In this situation, a lower pH is required than with higher, dry silage. This prevents the colonisation of harmful bacteria.
Wet grass will create a large amount of effluent in the clamp, this being detrimental to the environment if it is incorrectly dealt with. It is important to cut grass during good weather as it contains valuable nutrients which should not be wasted.
Wilting is an important stage in the silage process which reduces effluent. The process includes shaking the cut grass out to allow it to lose moisture. However, during this stage, the plant continues to respire. As the sugars break down, there is a loss in protein and quality.
If the wilting stage is prolonged, harmful bacteria can colonise and further reduce the quality of the product which increases the need for additives. It is important that the wilting period and grass sealing is carried out quickly, anaerobic conditions halting respiration.
Shorter chop lengths release more soluble carbohydrates, allowing for faster fermentation. The short length also means that the grass can be packed into the clamp more effectively, reducing the air pockets for better consolidation. There are also benefits when feeding out, the reduced time which is spent in the feeder wagon also minimising the amount of diesel used.
The height of the cut is also important, especially when considering regrowth. By leaving some growth, around 5cm, on the field, the grass will be able to recover at a faster rate. This allows the next cut to be achieved sooner, reducing the risk of soil contamination.
Additives, while not having the ability to transform poor quality silage into good silage, can prevent excessive losses and stop bad silage from worsening. Applying silage additives depends on factors such as weather conditions and the cut number.
While additives are costly, they are especially useful when targeting specific problems such as cutting grass in wet weather.
We at GSS are very happy to talk to you about additives and make recommendations, please get in touch.
Different Silage Additives
There are multiple kinds of silage additives which each have their effects on the soil, including:
- To provide additional soluble carbohydrates
- To increase the acidity of the grass (this kind of additive should be used on wet grass when the level of soluble carbohydrates is low)
- To add bacteria species, also known as lactobacilli, which can improve fermentation or improve stability when the clamp is opened