The potential of this year’s maize crop looks set to give dairy farmers an opportunity to clamp decent tonnages of quality silage, which could provide a useful buffer given uncertainty over milk prices, said Volac silage expert, Ken Stroud.
However, it will be crucial to avoid common harvest pitfalls that let dry matter (DM) and nutrients slip away in the clamp.
“While some maize crops haven’t fully recovered from the dry spring, most look in good shape,” Stroud said.
“Conserving good stocks of quality silage, to become more self-sufficient in winter feed and maximise milk produced from homegrown forage, makes sound financial sense in times of volatility.”
Typically, about one in every 10 trailer loads of maize DM ensiled are lost due to unwanted bacteria, yeasts and moulds growing in clamps, according to Stroud, but losses can double if attention to detail slips at harvest and ensiling.
“Unwanted microbes come into the clamp on the crop at harvest (see infographic, right),” he said.
“You can’t completely stop this, but inhibiting their growth in the clamp is vital. This requires attention to detail at several stages (see table).
Tip Reason Clean the clamp before harvest To remove undesirable bacteria, yeasts and moulds surviving on old silage and in cracks Harvest maize promptly at 30 33% dry matter (DM) To provide a balance of: Starch content in cobs – for energy, foliage that is still green – for digestibility, and crop still sufficiently ‘soft’ for consolidation Leave at least 15cm of stubble Because the stem base is: Low in nutritional value, at risk from soil bacteria that interfere with fermentation, and at risk from yeasts and moulds Chop to the optimum length (e.g. 1.5-2.0cm) So the maize is: Short enough to aid clamp consolidation and long enough to perform in the rumen Treat with a dual-acting additive To target a more efficient fermentation and to target the yeasts and moulds that cause losses from heating (aerobic spoilage) Fill the clamp in maximum 15cm layers, roll with sufficient weight and sheet thoroughly (side sheets, an O2 barrier film & well-weighted top sheet) To aid consolidation and keep air out – since oxygen trapped in silage allows yeasts and moulds to thrive (Typically, maize at 30% DM requires 25% of its weight arriving at the clamp/hour to consolidate it. So 100t/hour requires 25t rolling constantly)
“All these stages are important. But there are three common pitfalls that could be particularly important to avoid this year.”
Maize: Common pitfalls
1. Harvesting maize too late:
Harvesting maize late, when it is dying back, not only risks the crop being past its nutritional peak said Stroud, it also increases the risk of unwanted microbes coming into the clamp on the dying foliage.
“Too often maize is harvested when leaves are dying or dead. It should be harvested as soon as it reaches 30-33% DM and ideally while still green,” he said.
“Doing this provides a good balance of starch in the cobs and living foliage with higher nutritional value. Crops harvested drier are also harder to consolidate, leaving them prone to losses from heating caused by aerobic spoilage.”
2. Thinking maize ‘conserves itself’
A common myth is that maize does not benefit from conserving with a silage additive. But after investing in growing the crop, ensiling it untreated leaves its conservation at the mercy of whatever microbes are on it.
“Maize silage suffers two types of losses: Obvious losses from heating, caused by yeasts and moulds growing in the presence of air; but also invisible losses from poor fermentation, due to inefficient fermentation bacteria,” Stroud said.
“Both waste the silage’s DM and energy and release carbon dioxide, which is a greenhouse gas.”
“You can’t regulate which types of bacteria, yeasts and moulds are present at harvest,” he added.
“But applying a dual-acting additive, such as Ecocool, containing beneficial bacteria effective against both problems, drives in favour of a quality fermentation to put you in better control.
“For peace of mind of an efficient initial fermentation, one of the bacteria in Ecocool is the same proven ‘MTD/1’ strain found in the highly-respected additive, Ecosyl.
“Meanwhile, the second of the bacteria in Ecocool, ‘PJB/1’, is specifically included to inhibit the yeast and mould growth that otherwise causes maize silage to heat up. Indeed, Ecocool has been shown to keep maize silage cool and stable for more than 10 days after exposure to air.”
3. Harvesting maize too low
Although tempting to cut maize low to the ground – especially if looking for extra bulk – the stem base is low in nutritional value and typically higher in unwanted microbes, so you risk losing more than you gain.
“Instead, ask your contractor to leave at least 15cm of stubble,” Stroud said.
“Similarly, make sure they chop the crop short enough to aid consolidation, especially with drier crops, but long enough for it to perform in the cow’s rumen. Consider a 1.5-2.0cm chop length, or 1.2cm if needed.”
For more information on the Volac range of Ecosyl silage additives, click here.
