Cows are designed to eat forage, so making and feeding high-quality digestible silage are essential. Maximising forage intake is key to improving farm profitability. Poorer quality silage requires additional supplementation to achieve the same performance, bringing in additional feed costs.
For example, if a cow eats 10kg (approximately 43kg fresh weight) of dry matter (DM) of a 75 DMD silage with a UFL content of 0.85, her energy intake is 8.5 UFL. Whereas if the cow eats the same amount of a poorer silage (65 DMD) with a 0.72 UFL, she will only get 7.2 UFL of energy. While this difference of 1.3 UFL seems small, it is enough energy to produce three litres of milk. For the second cow to achieve the same performance as the first, an extra 1.5kg of concentrate will be required.
The most common forage in animal diets in Ireland is grass silage; however, it is the one element of the diet that varies greatly from clamp to clamp. Regardless of your system, high-quality grass silage is vital. The objective on every farm should be to produce high quality silage and improve efficiency by reducing field and clamp losses where possible. Planning should happen well in advance to ensure high-quality silage; good fermentation will increase palatability and make sure that you have enough quantities.
Good-quality grass silage should have a UFL >0.8 or a metabolisable energy (ME) of 11.5–12 MJ/kg DM, a crude protein of at least 14 per cent and a DM content of 27-30 per cent. While fertiliser and slurry will already be applied at this stage, this should be tailored to your own farm needs. Representative soil testing should be done regularly to ensure optimum soil fertility levels. Optimum soil pH is also crucial and should be between 6-6.5.. Without this basic feature, you will struggle to manage the other parameters.
At harvest, we need to be careful if there is still nitrogen in the grass. Excess nitrogen impacts grass ensilability, which may result in poorer fermentation. Too much nitrogen can produce grass with low sugar levels, meaning the silage could have high ammonia and butyric acid, causing palatability issues. On the other side of that, too little nitrogen can cause low-protein silages and reduced yields, as we saw last year. We sampled over 600 silages last year, and our average crude protein value dropped from 14.3 per cent in 2021 to 11.6 per cent in 2022, causing significant issues this past winter.
The biggest factor that contributes to nutritional value is cutting date. For the highest-quality silage, an early cutting date, before the plant has headed and a seed head is visible, is vital. Beyond this point, the DMD value will decline by 0.5 units each day. So, aim to cut just before the seed head emerges. Do not sacrifice quality for quantity, as it is possible to achieve both. Aim for an early May cutting date; any later will affect second and third cuts and cause forage quality issues for the remainder of the year.
While it is not always possible, cutting on a dry, sunny day is ideal. Grass sugars are at their peak in the afternoon, but you also need to consider a fast wilt, because an overnight wilt might not be adequate. Both factors need to be considered. Wet ensiled grass will be too acidic and produce an unpalatable feed. Effluent is also likely at a DM of less than 25 per cent. A target DM of 27-30 per cent is ideal. Grass can also be too dry, resulting in consolidation issues, poor ensiling, or secondary fermentation in the pit and in aerobic spoilage or heating once opened. To discourage soil contamination and encourage good regrowth, the mower should not be dropped below 6-7cm. Once cut, the grass needs to be ensiled as quickly and cleanly as possible to prevent losses (<24 hours). A longer wilt time leads to bigger losses. Chop length should be 2.5-5.0cm for 25-40 per cent DM crops.
Irish weather can be unpredictable, and we need to bear that in mind here. If weather conditions are difficult, mowing should be held off until the weather settles. However, do not delay too long, as soil contamination will become an issue. If possible, use different access points in fields and make sure the area in front of the clamp remains free from soil. Work downhill and make sure tyre pressures are correct for the conditions. Part-filling trailers should also be considered. Be prepared and remember that wet grass will also produce a lot of effluent.
Silage additive can help make good silage great, but it will not compensate for poor silage management, and a particular additive is not always ideal in all farm circumstances. A homofermentative additive that supplies one million bacteria, such as Alltech’s EGALIS, can help improve silage quality. The aim of EGALIS is to speed up the fermentation process using lactic acid bacteria, reducing the pH to the required level and preserving more of the nutrients in the crop.
The result is increased performance and less waste, which fits in well with the focus on improved efficiency and sustainability. You will have to make an informed decision based on the conditions and allow adequate time to get the product and the correct equipment for application.
Preparation is key
Put aside time to prepare the clamp before harvesting begins. This can help speed up the operation. Old, mouldy, rotten silage should already be removed from the clamp. To ensure quality, the clamp needs to be filled as quickly as possible, paying good attention to detail. Good compaction from the very start is vital for clamp stability and to reduce losses. Even filling and regular rolling is a must; however, avoid rolling the next morning before filling if a pit has been left overnight, as this will draw in air. Clamps should be filled in a wedge shape. Do not overfill; consolidation above the walls will drop significantly, creating losses. Finally, the pit needs to be sealed as soon as all compaction is complete.
Paying good attention and allowing the correct time and preparation for all stages of silage-making should help improve silage quality, save on feed costs, and bolster animal performance.