Silage update

Published 15 November 13

Adam Clay, ruminant manager at Frank Wright Trouw Nutrition, provides the very latest seasonal information on silage qualities and outlines what effects these might have on animal performance.

Grass silage

Average grass silage this year is 0.2 ME (10.7 Vs 10.5) higher than 2012 forages. This rise alone will contribute nearly half a litre increase in milk production

Dry matter has increased by 2.4% (33.7 Vs 31.3), sugars by 1.1% (3.7 Vs 2.6), and, along with a reduction in Neutral Detergent Fibre (NDF), lactic acid and lignin (the indigestible fraction of fibre) intake characteristics are high leading to a potential of lifting milk from forage this winter. While this must be seen as a positive it is still important to be aware of rumen health.

Dry forages make it easier for cows to sort through the ration and select the more palatable ingredients. This means cows do not have a uniformed diet, as they root out the more palatable concentrates and consume large amounts in a short period of time. Not only will this change the diet for the rest of the day, it is also likely to cause rumen acidosis which will decrease intakes, milk constituents and milk yield. Look out for low cudding rates, cud balls, loose cows and reduction in performance. If this is occurring consider chopping forages shorter, as this will reduce sorting, and the use of an appropriate buffer.


Wholecrop averages were lower quality this year. ME dropped 0.2 (10.2 Vs 10.4ME) and starch dropped by 4.5% (19.2 Vs 23.7%). However, this fall should be balanced by an improvement in grass and maize silage, not to mention the benefit wholecrop will have on rumen health

Maize silage

Maize silages are looking strong this year with a 0.2 ME rise (11.4 Vs 11.2) and 6.9% increase in starch. Further increases in dry matter (30.8 Vs 29.5%), D value (72.2 Vs 70.8%) and reduction in NDF (45.1 Vs 50.7%) mean that intake potential is high, due to better digestibility of the forage this year.

The rumen degradability of the starch is 65%, which means 65% of the starch in maize is broken down in the rumen. Over time, as the silage sits in the clamp, the starch becomes more degradable in the rumen. This means a diet which is formulated now may be healthy on the rumen today, but come the new year starch in the silage is more available, potentially increasing the risk of acidosis. So less rumen energy and more by-pass may need to be formulated for a correct diet.

For more information sign up to DairyCo’s webinar ‘Monitoring rumen pH’ on 19 November with Professor Toby Mottram from the Royal Agricultural University.