Silage makes up the largest proportion of winter feed fed on beef and sheep farms in Ireland. It represents a massive cost each year in terms of growing it, ensiling it and feeding it and yet it doesn’t seem to get the attention it deserves on many drystock farms.

Winter performance in cattle, especially in young weanlings, can drop below target on many farms due to incorrect supplementation and not meeting an animal’s nutritional requirements. Silage quality can have a huge effect on this and silage quality will determine the level of concentrates required in all cases.

The nutritional requirements of different animals, eg an autumn-calving suckler cow v a dry cow, can vary and it’s important to have a feeding plan to make sure all animals are getting the correct feed. It’s a simple test that is carried out by most feed companies for clients to determine silage quality. Taking an accurate sample with a silage corer is important to get an accurate analysis.

Your silage report: what to look for?

Dry matter (DM)

This is the amount of silage remaining after water has been removed. The energy and protein value of silage is quoted in %DM. The higher the DM, the higher the intake of energy and protein will be for every 1kg of freshweight silage the cow eats. In general, lower DM silage will have lower intakes and higher DM silage will have higher intakes.

pH

A well-preserved silage should have a pH of 3.8 to 4.2. Wet silage with a high pH will not keep as well and will usually indicate a silage that has not fermented well and silage intakes will be low. If pH is below 3.8, this can lead to acidic conditions, a sharp smell and cows throwing up ‘cud balls. Dry silages can have a higher pH and good preservation.

Ammonia levels

High ammonia levels show poor preservation. This can be due to high grass nitrogen levels at cutting or low-sugar, wet and young grass being cut. Values of <5% indicate excellent preservation, while >15% will lead to reduced intakes.

Crude protein

This measures the protein concentration. Young leafy reseeded swards will have higher protein values. Inadequate fertiliser applications can lead to lower protein levels. Values greater than 15% indicate young leafy swards.

ME (MJ/kg DM)

This is the amount of energy in the silage. Young grass will have the highest energy, while mature grass will have lowest energy. The younger and drier the grass, the more energy the silage will supply for milk production and liveweight gain.

DMD value

This is a measure of the feeding value of the silage expressed as a percentage. Late-cut old swards can have a DMD as low as 55DMD, while excellent leafy silage can be more than 75DMD. Silage with a high DMD will be digested quicker and lead to higher intakes

Lactic acid percentage

Bacteria in fresh silage uses grass sugar to make lactic acid which aids the ensiling process by pickling the silage. Cutting young grass in sunny conditions will lead to high lactic acid percentage. A well preserved stable silage will have a high percentage of lactic acid. Levels of 8% to 10% are classified as very good.

Neutral detergent fibre (NDF)

This is a measure of the total fibre content in the silage. Late-cut mature stemmy silage will have a high NDF.

  • Young grass: 45% to 50%.
  • Average: 55%.
  • Mature grass: 60% to 65%.

    • Intake value

    This is a relative measure of the likely intake of silage. HFIS is the unit measure for beef cattle. This ranges from 50 to 105, and a higher figure indicates high DM, high DMD and low ammonia.