Protect maize to help offset grass silage shortfalls
11 August 2025
Be vigilant to minimise losses in this year’s forage maize crops after the dry season has left many farms facing grass silage shortages, a livestock specialist is urging.
According to Volac technical business manager, Amanda Clements, although maize crops are variable this year, they could still provide something of a lifeline for farms facing low grass silage stocks or disappointing grass silage quality.
The key will be to protect whatever dry matter (DM) and feed quality there is in maize at harvest and ensiling, she says. To help, Amanda suggests a three-point checklist:
Understand what is at stake
Start by understanding what is at stake, nutritionally, if maize is not harvested in a timely manner, says Amanda, and the potential losses in the clamp. 
“Harvesting maize too early means cobs won’t contain enough starch and will be too wet,” she explains. “Harvest too late, when the leaves are dying, and the feed value of dead maize foliage is like feeding straw.
“Additionally, maize suffers two types of in-clamp losses – obvious losses when the silage heats up, caused by yeasts and moulds growing in the presence of air, and hidden losses due to poor fermentation from inefficient fermentation bacteria. Typically, about 1 in every 10 trailer loads of maize DM ensiled is lost, but losses can reach double that if management is poor.
Also, understand that the unwanted microbes that cause losses feed preferentially on sugars and starches, so the remaining DM will be of lower feed quality where losses occur.
Harvest correctly
To harvest maize at its nutritional peak, Amanda says cobs should be ripe, leaves still green, and the whole crop be at 30-33% DM.
“To check cob ripeness, select 10 representative cobs from the field,” she says. “Upper kernels should have a soft cheese texture, while a thumbnail should leave no indentation in kernels at the cob base, and the milk line in kernels half way down cobs where the milky liquid turns to solid starch should be one-half yellow starch. 
Also, although it might be tempting to cut lower if looking for extra yield this year, avoid cutting maize any closer to the ground than 15cm. The stem base typically contains more spoilage microorganisms and has poor nutritional value.
“Similarly, maize should be chopped short enough to aid consolidation; for example consider 1.5-2.0cm or 1.2cm if needed, depending on the %DM. And if ever there was a year to reduce maize losses by preserving it with a quality silage inoculant, this is it.
“The dual-acting inoculant Ecocool has been proven to cut DM losses associated with heating and those associated with inefficient fermentation. It’s also been shown to significantly limit the accumulation of mycotoxins on maize after ensiling when exposed to air, provided these mycotoxins are not already present at harvest.”
Care for the clamp
Also important for minimising losses, says Amanda, is attention to detail at the clamp. “Ensure clamps are clean and free from old silage that harbours mould spores, and that machines aren’t introducing soil or slurry on their tyres.
“Keeping air out of silage is also important to reduce yeast and moulds and for fermentation. So line clamp walls with polythene and don’t skimp on consolidation. Typically, maize at 30% DM needs 25% of its weight arriving at the clamp per hour for consolidation. So 100 tonnes per hour requires 25 tonnes, which is two machines rolling constantly. Filling in horizontal layers no more than 10-15cm deep also aids consolidation versus filling in a wedge shape.
“Once consolidated, place an oxygen barrier film on top to seal the maize surface, and fold side sheets over this all around, before adding a fully-weighted polythene top sheet then a woven sheet. Use netting to prevent bird damage and ensure rodents aren’t a problem,” Amanda concludes.
This year, every tonne of maize counts. Timely harvesting, good clamp practice, and effective preservation could make the difference in keeping herds well-fed through winter.