Winter feeding - The importance of silage analysis

Date published: 17 October 2024

Farm businesses often spend a significant amount of time, money and effort getting silage ensiled correctly, however with all this effort we often fail to get an understanding of its quality. To keep input costs to a minimum it is crucial that silage is analysed to understand if any supplementary feeding is required and at what level.

It is important that silage is tested every four weeks to ensure that any changes in quality are accounted for. Simply guessing what the silage quality is may result in under or over-feeding. This can influence livestock health, fertility and performance, adding cost to the enterprise.

To ensure the silage analysis results are useable and accurate, it is important to submit a sample that is representative of what you’re feeding to stock. A pit of silage can be tested before it is opened using a corer or by taking a sample from the face of the clamp once the pit is opened.

To take a sample from the face of the clamp work across the face in a ‘W’ shape taking 10-12 samples. Ensure the samples are taken 20cm back from the face. This will avoid silage that has been exposed to rain and sun at the face of the clamp which can affect the dry matter reading.

Ensure samples are not taken from deteriorated areas and not from the top 50cm of the clamp. Take a handful of silage from each testing spot, combine in a clean bucket and mix well. Empty the sample onto clean ground and mix again before splitting and filling sample bags to the correct level.

For baled silage take samples from five bales and thoroughly mix the samples together. Ensure any holes are resealed to prevent any deterioration of the bale.

Ensure all the air is expressed from the sample bag, this prevents any deterioration of the sample. The sample is now ready to be analysed. This can either be completed using on farm testing machines or posted to a certified lab for testing. If the sample is being posted ensure it is sent away early in the week. This will ensure its not sitting at a delivery depot for a long period which will degrade the sample.

The silage analysis report will cover several parameters. Different groups of livestock will require different levels of silage quality. The dry matter (DM) measures how much of the silage isn’t water. If the silage is less than 25% DM, then it can be difficult for livestock to eat enough to meet their requirements. The digestibility value (D value) measures how digestible the silage is. This is often affected by cutting date, with younger grass having a higher D value.

Metabolisable energy (ME) shows the level of usable energy that the silage provides to livestock when fed. This along with crude protein (CP) levels are an important consideration for growing stock. Ash content is also a parameter to consider as it gives the level of mineral and trace elements in the silage. Silage with an ash content of 10% or above would indicate soil contamination. This can affect feed intakes, livestock health and performance.

If you require additional information or help understanding your silage analysis results, please contact your CAFRE Adviser through your local DAERA Direct office.