Silage accounts for 30% to 40% of the total feed bill on beef and dairy farms and is an essential and integrated component of most of our livestock production systems.

  • It provides home-produced feed for when it is not feasible for livestock to graze grass.

  • It facilitates managing the supply and quality of grass for grazing at parts of the year.

  • It provides aftergrass for grazing that has particularly low parasite burdens.

  • It permits the efficient and safe recycling of slurry onto grassland.

    • Clearly, it is important for commercial farms to provide adequate amounts of appropriate digestibility silage at the lowest cost practicable.

    The complete livestock production system on any farm has a unique requirement for silage with particular digestibilities.

    The cost of providing these silages is influenced by digestibility of the crops harvested, by the efficiency with which they are ensiled and fed to livestock, and by the costs of the variable and fixed inputs involved in silage production, harvesting, storage and feed-out.

    The following are two important factors in providing the required silages on farms.

    Soil fertility

    Sub-optimal soil fertility is probably the single most important factor restricting farmers’ ability to achieve target silage yields and digestibilities at present.

    Approximately 90% of the soil samples currently analysed for Teagasc are showing up for potassium or lime (pH).

    This means that many fields used for producing silage this year will not respond optimally to the nitrogen fertilizer applied (or to the nitrogen supplied in slurry).

    Therefore, the economic and biological reward for providing nitrogen will be sub-optimal. It further means that the yield of grass available to harvest when the crop is at an optimal growth stage will likely be lower than required.

    In many cases, the management response will be to defer harvesting by some weeks until grass yields have increased sufficiently. However, grass growth stage changes rapidly during May and June.

    Each week of delay in harvesting results in a 2% to 3% unit decline in its digestibility and, therefore, in the rate of animal performance it will support. Deferring silage harvest date will consequently result in sub-target animal performance. It will entail the input of supplementary concentrates to prevent performance declining.

    If you consider that it will require a supplementation of rate of approximately 0.6kg to 0.9kg concentrate per day to make good the drop in animal performance resulting from the lower digestibility associated with a one week deferral of silage harvesting, it makes it apparent that the cost of sub-target digestibility can be severe.

    In addition to the above concerns, sub-optimal soil fertility makes it difficult to maintain perennial ryegrass in swards. Instead, there will likely be an increase in the content of weed grasses such as bent grass (Agrosis) and often of broad-leaved weeds such as buttercups.

    These dis-improvements in sward botanical composition further limit the yield potential of the crop. They reduce both sward digestibility and the ease with which it can be preserved for silage.

    The preservation challenge results from the much lower sugar contentof weed grasses, etc., compared to ryegrasses.

    Most Irish farms have some silage fields that are deficient in potassium or lime, and, on many farms, most silage fields are wanting.

    The first step in dealing with this is know the facts so that the optimal management decisions can be made.

    This means that each silage field needs to be representatively soil sampled and an analysis obtained for phosphorus, potassium and lime.

    A plan then needs to be put in place to restore soil phosphorus and potassium status to soil index 3 and pH to approximately 6.3 (mineral soils).

    This can be an expensive investment but will be necessary where high outputs of animal product per hectare are targeted.

    It’s justification is more apparent when the silage production process involves paying contractor charges on a per hectare basis (e.g. precision-chop silage).

    In some situations, the correction of phosphorus, potassium or lime deficiency in a field or an entire farm will allow acceptable grass productivity for silage production (relative to the needs of that farm) to be restored.

    In other cases, it may also be necessary to renovate the sward by reseeding. In some conditions, it may be required to overcome soil physical limitations, such as water-logging, if full silage production productivity is to be achieved.

    These issues clearly have sizeable financial implications and should be addressed as part of a longer term farm business plan.

    Reserve silage

    One of the restored truths of the past few years is, and one of the implications of predicted climate change patterns for Ireland will be, the need for a reserve of silage over and above the immediate needs for a normal winter.

    This means that, in addition to budgeting feed supplies to meet herd requirements for the next winter, the overall farming system must have sufficient inbuilt flexibility to be able to cope with the need to sometimes house livestock early in autumn.

    It must also be able to cope with the need to keep them indoors later in spring or rehouse them during part of the grazing season.

    The importance of this strategy increases where stocking rates on farms are higher. Among the strategies to amass this reserve of silage are:

  • Optimise existing grazing management in order to provide as much as feasible of the annual feed requirement by grazing. This involves applying strategies to increase the yield of grass available to graze, improving its rate of utilisation and availing of opportunities to graze earlier in spring or later in autumn.

    • Besides reducing the overall feed bill, excellent grazing management reduces the amount of store silage that will be used in the intervening winter, thereby facilitating establishing or increasing a reserve of silage.

  • Avail of the opportunity to harvest and ensile surplus grass on grazing paddocks when it occurs during the grazing rotation. It will often be most convenient to conserve this surplus as baled silage. Where this is done efficiently, the resulting silage will sometimes have a digestibility (DMD) of approximately 80% and thus be of really excellent feed value.

  • Allow some grazing paddocks continue to grow to produce silage crops. Again, this is opportunistic and depends on the needs of grazing livestock being comfortably met under the prevailing short-term circumstances.

  • Plan to produce a second cut of silage, expand its area or increase its yield, as circumstances permit. This requires that, where slurry needs to be spread, it is done within a day or two of the first cut being harvested, and that the required input of fertilizer follows three to four days later.

  • Minimise losses or wastage at all stages of silage making, storage and feed-out. There are farms where over 80% of the grass harvested for silage is subsequently eaten by livestock and there are cases where much less than 70% is eventually consumed. These differences reflect different on-farm management strategies. The difference can be sufficient stock for three weeks. Reducing silage wastage is therefore crucial to creating a reserve of silage.

    • Two essential considerations in managing reserve silage are, firstly having excellent silo management so that this reserve can be maintained efficiently from year to year, and, secondly, being able to accurately quantify the amount of reserve silage in storage.

    Densely packed, leafy moist silage will likely be easiest to successfully store over several years, once it is preserved properly and is well protected from air.

    Baled silage will not be as well suited to storing over several years and should be used by its second winter in storage.