Making the most of maize

With strong milk prices, high feed costs and the drive to farm sustainably, be sure to capitalise on this year’s forage maize crops as a high-energy, home-grown feed.

One of the best ways to maximise maize is to minimise nutrient losses and wastage when turning maize crops into silage.

When ensiling, maize can harbour a range of undesirable bacteria, yeasts and moulds, particularly on joints where rotting tassels collect and on dying leaf tissue. The bacteria feeds on its nutrients and interferes with preservation in the clamp.

Volac silage expert Ken Stroud said: “Unless prevented, these microbes cause typical losses equivalent to one trailer load of dry matter (DM) out of every 10 trailer loads ensiled.

“These are average losses and they can be much higher – particularly around the top of the clamp where they might be 50%.

More importantly, losses aren’t just the least nutritious parts of the DM. They are likely to be sugars and starches, which are the main energy sources of maize.”

To help our farmers minimise losses and lock-in the maximum benefits of maize, Volac has prepared a five-point checklist of some best practice harvest and ensiling tips.

1. Harvest maize at its peak

Maize is often regarded as only ready to harvest once it dies back. But the optimum time is actually as soon as it reaches 30-33% DM content which is usually while the foliage is still green.

Mr Stroud said: “Waiting longer can increase starch in the cobs. But if this is at the expense of leaves dying back, then the plant will become less digestible and this dead leaf tissue will harbour nutrient-robbing microbes, like yeasts and moulds.

“For a timely harvest, monitor the crop’s increasing DM regularly. That way, you can give your contractor advanced notice of when 30-33% DM is likely to be reached.”

2. The fermentation trap

Avoid thinking maize always ferments efficiently. As well as suffering losses through clamp heating it can suffer invisible DM losses due to inefficient fermentation and the bacteria that feed on sugars, so the metabolisable energy of the silage will also be lower.

Mr Stroud said: “Take steps to improve fermentation by applying a proven bacterial additive. In trials, an additive containing the efficient fermentation bacterium Lactobacillus plantarum MTD/1 has cut DM losses and resulted in increased milk yield per cow per day.”

3. Head-off heating or aerobic spoilage

Losses from heating occur due to yeasts and moulds growing on the silage in the presence of air. Airtight conditions in the clamp are crucial, but this alone is not always sufficient, particularly in clamps with wider faces which, once opened, are exposed to air for long periods.

As well as airtight conditions, applying a dual-acting bacterial additive allows you to target heating losses and inefficient fermentation in one go.

The additive Ecocool contains a tailored dose of MTD/1 bacteria for fermentation but also a second bacterial strain, Lactobacillus buchneri PJB/1, to inhibit yeast and mould growth. It has been shown to keep maize silage cool and stable for more than 10 days.

4. Clamp down on consolidation

Do not compromise clamp consolidation. It can be tempting to rush it, but you could be living with the consequences of poor preservation due to air in the clamp for a long time.

Shorter chop lengths are useful to aid consolidation, especially if the maize is dry. Consider chopping to 1.2 to 2.2cm. Also, fill clamps at a maximum angle of 20 degrees to the horizontal and in layers at most 10-15cm deep for maximum benefit from compaction machinery.

Mr Stroud added: “Typically, maize at 30% DM requires 25% of its weight arriving at the clamp per hour to consolidate it. So, 100 tonnes per hour requires 25 tonnes, which means at least two machines rolling constantly.”

5. Keep out air

Once air has been squeezed out, keep it out by creating an airtight bag in the clamp. This means lining the walls with polythene down to the ground because concrete can be porous and placing an oxygen barrier film on top of the maize, which clings to it to seal the surface.

Mr Stroud concluded: “Side sheets should have at least a one metre overlap on top of the oxygen barrier film, before the top sheet is pulled tight over the oxygen barrier film. Use a heavy, woven sheet over the top sheet to protect against damage, followed by plenty of weight. Remember, clamp bases rarely suffer from heating and spoilage because of the weight of the silage above.”