Essential plan to optimise silage management on farms

A lot of silage was fed in March and April and there are very little reserves on most farms.

Essential plan to optimise silage management on farms

With grass growth at less than half the normal until May, there are some serious problems on farms.

The difficult task of providing fodder for next winter is already staring many farmers in the face even though they are still struggling with providing sufficient grazing.

Very few farmers had the opportunity to close up sufficient ground in early April for first cut silage. Farmers who closed up for silage in early April are preparing to harvest as soon as the opportunity arises.

Despite the fact that Irish farmers have been making grass silage for half a century, it is disappointing to find that average silage quality, as indicated by analysis of tested samples (average 66% DMD last year), seem to be deteriorating rather than improving. Some farmers make excellent silage every year (75 DMD+) but most samples tested are only in the mid to high sixties.

With the end of milk quotas, silage will make up a higher proportion of feed than in the past as cows will calve earlier and will be milked later in the season. Therefore, farmers should focus more on quality rather than on bulk.

High DMD silage will boost animal performance and reduce the requirement for expensive concentrates.

Poor quality silage will result in poor animal performance that not only have serious economic effects during the feeding period but also for long afterwards.

For example, poor quality silage can reduce milk production by one gallon per day and often results in cows calving in poor condition with increased fertility problems and replacements falling far short of optimum targets unless a lot of concentrates are fed.

There are many reasons for poor quality silage. The weather and the contractors can take some of the blame. However, there are other reasons for poor quality silage.

The first essential for top quality silage is to have a good clean ryegrass crop properly fertilized and this is very often lacking. Many crops are allowed to overgrow and lodge badly.

Other farmers close up silage ground too late in April resulting in very stemmy material which naturally goes to seed in the first few weeks of June.

Excess or late application of N fertiliser or slurry reduces sugar levels in the grass and makes it more difficult to preserve.

Inadequate preparation for harvesting and covering are a frequent cause of problems.

The contractor practice of charging by the acre rather than by time encourages some farmers to allow crops to “bulk up” and this is bad for the farmer and the contractor.


Despite the growth in alternative feeds, grass silage, especially good first cuts, will remain the cheapest and most suitable source of winter feed on the vast majority of spring calving dairy farms.

A good crop of first cut grass costs only half as much as lighter and later cuts in terms of tonnes of digestible DM. Average losses in silage making are 15% to 25% and the aim should be to keep these losses at a minimum.


Unlike other aspects of farming, the technology for making good silage has changed very little over many decades.

The scientific basis for making good silage is that the grass is sealed off from air as soon as possible to prevent bad bacteria (which requires air) to cause deterioration.

This allows lactic acid bacteria present in grass to break down sugars into lactic acid which will give good preservation and result in very good silage.

A good crop of ryegrass is the first essential for top quality silage. However, this is no guarantee of good silage. If harvesting is delayed or if crops are badly preserved, performance will be reduced.

Teagasc trials showed that the advantage due to good fermentation versus poor fermentation on the performances of beef animals being fed on silage from the same grass is 50% extra carcass gain. Poor quality grasses have low feeding value and are difficult to preserve because of low sugar content.

During the quota years, some dairy farmers went for later heavier crops as lactations were often very short.

Very heavy or lodged crops have a very bad effect on sward recovery, and damages swards.

Cows need good quality silage during the dry period so that they calve down in proper condition. Replacements also need high quality silage.

The DMD value of silage is the best indicator of its feeding value. Silage yields can increase by up to 2 tonnes per acre per week and DMD declines by over 2 units DMD per week after heading out and double this rate if crops are lodged.

Poor fermentation can decrease DMD by up to 7 units.

Ryegrass has 2 to 4 units higher DMD and is easier to ensile than poorer type grasses.

Each drop of 5 DMD reduces milk yield by almost half a gallon of milk per day and increases the cost of finishing cattle by over €70.

Trials show that finishing cattle without concentrates can gain 0.51kg carcass weight on 75 DMD silage while they only gain 0.33 kg on 67DMD silage.

The ideal time for harvesting is when the crop is heading out (DMD 75+) but this is difficult to judge in a crop with mixed species of grass.

While silage DMD of 75 should be the target for feeding to most animals, a well preserved lower DMD (68-70) would be sufficient for dry cows in good condition.

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