Testing silage now is crucial, as many cows around the country are going to be milking through the winter months, with their main source of nutrition being silage.
That silage must be of good quality in order to pump milk production and make the most of the winter milk contract.
Farm businesses often spend a significant amount of time, money and effort getting silage ensiled correctly, however, even after all of this effort, farmers often fail to get an understanding of its quality.
Having good quality silage will allow farmers to produce milk from mainly silage, which will reduce winter feed costs and increase profitability during the housed period.
Grass silage is the basis of most winter feeding systems and good animal performance is largely down to the adequate intake of quality silage.
It is important that silage is tested every four weeks in order to ensure that any changes in quality are accounted for.
Simply guessing what the silage quality is may result in under or over-feeding, which can influence livestock health, fertility and performance, adding cost to the enterprise.
College of Agriculture, Food and Rural Enterprise (CAFRE), beef and sheep adviser, Adam Jones, highlighted the importance of conducting a silage analysis as livestock farms prepare to open new silage stocks for the upcoming housing period.
Testing silage
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 (DM) 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 of the air is expressed from the sample bag, as doing so prevents any deterioration of the sample. At this stage, 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, send it away early in the week as this will ensure that it is not sitting at a delivery depot for a long period – causing the sample to degrade.
The silage analysis report will cover several parameters and different groups of livestock will require different levels of silage quality.
DM measures how much of the silage isn’t water, and 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 or dry matter digestibility (DMD) measures how digestible the silage is, and is often affected by cutting date, with younger grass that is cut early having a higher DMD.
Metabolisable energy (ME) shows the level of usable energy that the silage provides to livestock when fed and 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 which can affect feed intakes, livestock health and performance.
Winter milking silage
In terms of quality, for dairy cows in milk and growing heifers, DMD should be at least 72%, and 75% for freshly-calved winter milk cows.
The UFL (energy) for milking cows and young stock should be 0.83-0.88 UFL, as a higher UFL means more feed energy for milk solids and weight gain.
For your winter milking herd, the CP level should be above 14%- lower DMD and/or nitrogen (N) application will reduce your CP.
Your PDIE, which is your metabolisable energy supply is determined by your UFL and CP levels in the silage, and should ideally be at 80g/kg.
Your intake value will indicate the silage intake potential and should be over 105g/kg for cows that are milking during the winter.
Farmers must be mindful of the potassium (K) content of their silage, as high K silage fed from two weeks pre-calving will increase the chances of milk fever occurring, and so should be less than 2.2% pre-calving and during lactation, over 2.4% will pose no risk.
