Farm Ireland

Thursday 22 February 2018

Quality counts in the battle to refill empty silage pits

Gerry Giggins

THE silage season is at long last in full swing in some parts of the country, although other regions are only just kicking off.

As expected, silage yields are somewhat lighter than previous years, so there is an added emphasis on ensuring it is of the highest quality and that wastage is kept to a minimum.

Silage stocks that stretched back a number of years have been wiped out this past winter and spring.

The silver lining to that dark cloud is that some silage pits needing repair have finally been washed, cleaned and put right.

Forage, especially grass silage, is still by far the cheapest energy source on farm. To make the highest quality silage possible, do not delay in cutting it.

Dry Matter Digestibility (DMD) is the figure that a lot of beef farmers take for granted.

On the forage analysis sheet, the farmer's eye is generally drawn to the metabolisable energy (ME) figure only.

The irony is that ME is derived from the DMD value and DMD directly affects silage's energy value.

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There is an understandable temptation to go for the bulky cut to refill pits, reduce harvesting costs and save money.

However, when you factor in the cost of replacing the energy lost, a decrease in performance and the increased number of days spent using expensive finishing diets, the equation doesn't balance.

Even where suckler cows are the main category of animal being fed, the better the silage quality, the lower the overall cost in keeping them will be.

If the silage is of too high a quality for the cows, their ration can be diluted by including bulky and low-energy cereal straw.

Generally, straw is cheaper per tonne of dry matter than any other forage and will replace silage on a 5:1 ration.

The effect of manipulating the DMD, by cutting as early as possible, is clearly seen in the performance of the animal.

It will also be reflected in savings on purchased feeds and contribute to higher outputs from your beef enterprise.

An extra daily liveweight gain of 35 to 40g is possible per unit of DMD improvement. This will have a significant effect if, for example, silage of 76pc DMD is produced rather than silage of 66pc DMD.

The species of grasses present in the sward and their genetics are also a major contributor to the potential DMD of the silage.

Reseeding any grazing areas or silage fields that have been severely damaged over the past year should also be a priority later this summer or early in the autumn.

Maximising the leaf-to-stem ratio while not compromising yield is the goal that we all should be aiming for in silage swards and grazing areas.

The benefits of using a good quality silage additive are well documented. An investment of €1.50 to €2 per tonne on the advanced range of new generation additives that are now available has to be considered.

Most inoculants contain a combination of enzymes and bacterium that result in more stable forages and better utilisation.

When the appropriate amount of additive is applied, both the fermentation process and silage intakes are improved.

Improvements in the forage will also mean that animal performance is improved.

When high dry-matter silage is produced, the use of biological inoculants will greatly reduce aerobic spoilage at feed-out time.

Heating silage in the pit will also mean heating silage when it is fed to the animals, leading to a great loss in energy and feed value.

Heated silage, when added to other moist feeds, also accelerates the fermentation of all the ingredients in the ration, reducing their value and effect.

The presence of oxygen in the clamp due to poor consolidation or delay in covering will affect the fermentation process.

It is not unusual to see a silage pit with the top 20 to 30cm of poorer quality than the rest. This is a result of impaired fermentation due to the presence of oxygen.

I have seen farmers using cling film-like or thicker covers previously used exclusively on maize silage. They are less porous to air than black plastic and cling to the surface of the clamp.

Used in conjunction with secure covers, they should be seriously considered.

The same principles of silage-making should be followed whether you are making big bales or pit silage.

Aerobic spoilage losses can be higher if the correct amount of film isn't used or bales are damaged during transport or storage.

Gerry Giggins is an independent nutritionist. Email:

Irish Independent