Winter milk production is already an expensive way of producing milk, which means it is crucial that farmers test silage, as silage quality is the key to good animal performance and the cheapest way of producing milk in the winter.

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.

In general, when more meal has to be added to the cows’ diet during the winter milking period, it is being added to make up for the poor quality silage.

In order to ensure your cows are meeting their energy requirements and milking to their full potential, you must know your silage quality so you can make a winter feed plan to make cost-effective decisions on concentrate supplementation.

Test your silage

Silage testing is still not a frequent practice on many dairy farms, but farmers should ask themselves: ‘Would I be happy if I received a delivery of concentrates without getting information on its ingredients or feed value?’.

The fact is, that your silage quality is far more important for the cost and performance of the winter diet.

Silage that is made in poor conditions could leave the silage with a low dry matter (DM), low digestibility, low crude protein (CP), high ammonia levels and high acidity.

This will result in cows having low DM intakes and poor animal performance, which will result in farmers compensating in the form of concentrates, which is going to drive up costs.

In terms of quality, for dairy cows in milk and growing heifers, DMD (dry matter digestibility) should be at least 72%, and 75% for freshly-calved winter milk cows.

Dry cows needing moderate body condition score (BCS) gain will need silage at 68-70%. 

The UFL (energy) for milking cows and young stock should be 0.83-0.88 UFL, according to Teagasc, 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.

A simple, cheap test will give the farmer valuable information on this year’s feed and give good guidance on what to improve for next year.

With the test, farmers will also be able to make a plan for this year to bridge the nutritional gap in the most cost-effective way.

Preservation

Silage should be costed on a DM basis, and when silage is well preserved and cut in good conditions, the DM should be anywhere between 24-28%.

Too high of a pH points towards poor preservation and if it is too low, it could affect the cows’ intake. Ideally, pH should be 4.0-4.2.

Likewise with ammonia levels in silage, as high ammonia will indicate that the silage was poorly preserved and will have a knock-on affect on intake – ammonia should be less than 8%.

Lactic acid levels should be 8-10% of DM, with higher levels indicating a stable, well preserved, palatable silage.

Ash should be less than 8% of DM and if your ash levels appear to be higher, then it indicates a soil contamination issue on the silage ground.

Farmers should aim to maximise the amount of milk produced from forage and thus reduce the amount of bought-in supplementation and this can only be done by making sure to test your silage.