With many farms now feeding silage we would encourage our customers to arrange to get their silage tested. By testing the silage the diet can then be balanced properly in order to meet the nutritional demands of the animal and ensure optimum performance. A lot of information can be obtained from a silage analysis. Detailed below you will find how to interpret these results.

Dry Matter

·       Dry matter is the amount of silage remaining after the water has been removed.

·       The energy and protein value of silage is quoted as % Dry Matter.

·       The higher the DM the more energy and protein the animal will receive for every kg of fresh silage they eat.

·       Low DM limits intakes high DM stimulates intake.

·       Dry matter should be above 25 %.


·       pH of silage indicates how well it is preserved.

·       Aim for pH of 3.8 to 4.2.

·       Wet silage with a high pH will not keep well and is generally accompanied by high ammonia levels. This may indicate poor preservation or high nitrogen levels.

·       pH values below 3.6 are considered acidic and must be supplemented or buffered to avoid digestive upset.

·       Dry silage can have higher pH values such as 4.5 and above and still be well preserved.


·       High ammonia levels show poor fermentation. This may be down to a number of things;

o  High grass nitrogen levels at cutting or

o  Low sugars, young wet grass, poor wilting.

·       Additives can help overcome high ammonia levels.

·       More mature stemmy grass will have a higher sugar content and be easier ensile than less mature swards.


Standard of fermentation

Ammonia N %

Excellent <5%

Good 5-10%

Moderate 10-15%

Poor 15-20%

Very Poor >20%


Crude Protein

·       Protein indicates how mature the grass was at time of cutting.

·       Young reseeded swards have higher protein as protein content is higher in the leaf than stem.

·       Inadequate fertiliser may lead to poor protein.


>15% very leafy young grass

12-15% grass at normal stage of cutting

9-12% mature stemmy crops

·       As a general rule of thumb for every % decrease in protein below 16% in silage meal protein level should increase 1% above 18%for dairy cows.

Energy ME (MJ/kgDM)

·       Young grass will have the highest energy and mature the lowest.

·       The younger and drier the grass the more energy the silage will supply for milk and LWG.

o  Top quality 11.5+

o  Average 10.5-11.5

o  Poor <10

DMD Value

·       This is a measure of the energy an animal can get from the silage.

·       Poor late cut silage will have a DMD as low as 55% and a low energy value while excellent leafy silage will be >75% and have a high energy value.

·       DMD will also affect intake, as silage with a high DMD will be digested quicker thus allowing more intake.

·       High DMD values generally give high energy and protein levels.

·       A 3 unit drop in DMD will need an extra 1kg of concentrate to maintain DLWG.

Lactic Acid

·       Bacteria in fresh grass use grass sugar to make lactic acid during ensiling and this acid pickles or preserves the grass.

·       A well-preserved stable silage will have a high% of lactic acid, which is sweet smelling which will help encourage high intakes.

·       Poorly preserved silage will have large amounts of butyric acid which is a foul smelling acid and can lead to a lot of wastage in the pit.

·       High levels of lactic acid are obtained from high sugar grass cut in bright sunny conditions, which is properly ensiled and quickly sealed and preserved.


NDF (Neutral Detergent Fibre)

·       A measure of the total fibre in the silage.

·       Late cut, stemmy silage will have a high NDF.

·       Too much NDF will slow down digestion, restrict intakes and reduce performance in animals.

·       Too little NDF can cause acidosis due to rapid digestion.

o  Young grass/good maize silage 45 – 50%

o  Mature grass/legume silage’s 60 – 65%

o  Average 55%

ADF (Acid Detergent Fibre)

·       Measure of indigestible material in the silage.

o  Average 35%

o  Range 25-50%

·       High NDF and ADF will also show low DMD, energy and protein values.

Ash %

·       This will give a measure of the mineral content of silage.

·       Ash values over 10% usually indicate soil ororganic manure contamination at time of harvest which can increase the risk of diseases such as listeriosis, Iritis (inflammation of the eye) and botulism.

·       Soil is a rich source of iron and aluminium.This can cause a mineral imbalance in the animal as iron locks up copper and aluminium interferes with the uptake of phosphorous.

Ideal Silage

·       Dry matter 25%+

·       DMD 70%+

·       ME >11.0 MJ/kgDM

·       FME >70% of ME

·       CP 15%+

·       pH 3.8 – 4.2

·       NDF 50 – 55% (500 – 550 g/kg DM)

·       Ammonia < 10%

·       Lactic acid 8 – 12 % (80 – 120 g/kg DM)

·       Lactic acid % of total acid >65%

·       Ash 5%

To have your silage analysed by Roche's Feeds and get information to make a plan for winter feeding contact your local Roche's Feeds representative or call 061 308 111 for our main office.

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