Beating bad bugs in maize silage

21 September 2023

If you grow maize, chances are you’re serious about maximising milk from forage. Because maize silage is an ideal partner for grass silage.

But after all the expense and effort put into growing it, have you ever thought about the number of ‘bad bugs’ – bacteria, yeasts and moulds – that can be present on the crop when it’s ensiled, and which can affect its dry matter (DM) content and nutritional quality?

As well as fungal diseases that can live on maize, such as eyespot, smut and Fusarium, decomposing crop debris and dirt can become trapped in leaf joints. And if the crop is harvested after it has started senescing, then dead tissue is a breeding ground for undesirable ‘bugs’.

These are in addition to any soil microbes that get up onto the stem base, especially in muddy conditions.

Would you ensile grass in the same state?

No? Then what can be done?

Inhibit growth

In a nutshell, minimise the number of bad bugs that get into the clamp in the first place, then inhibit the growth of any that do.

Firstly, make sure the clamp area and any machines coming into the clamp are completely soil-free. But also, harvest at the correct time and cut at the correct height. 

Modern maize varieties often reach the optimum 30-33% DM content for harvest while still green. You don’t have to wait for them to die back. Also, as well as the stem base being a source of soil and mould spores, it is of low nutrition value anyway. So always leave at least 15 cm of stubble. 

To minimise the growth of bad ‘bugs’ that do get into the clamp, a suitable dual-active additive not only helps improve the fermentation, so that the pH falls faster and bad bacteria are inhibited sooner, it also inhibits the activity of yeasts and moulds that cause heating. That’s important because heating is a sure sign that some of the hard work and expense you put into growing maize is going waste.

Finally, consolidate the clamp thoroughly and seal fully. Maize needs compacting to a density of 700 kg of fresh weight per cubic metre. To aid consolidation, consider a chop length of 1.5–2 cm and fill clamps in horizontal layers no more than 15cm deep, not in a wedge shape. 

Seal with an oxygen barrier film on top. Use side sheets folded over this using a minimum 1-2 metre overlap, followed by a top sheet pulled tight, a well-weighted woven sheet, and netting to stop birds damaging the sheet and letting air in.

Maize silage can be prone to losses from inefficient fermentation. These losses are invisible and can run at about 8% for maize harvested at the recommended dry matter content. However in some cases they may be higher – e.g. with some suggestion that DM losses can be as high as 20-30% between the field (pre-harvest) and what finally ends up in the rumen.

Some examples of the benefits of including Lactobacillus plantarum MTD/1 bacteria to produce a faster, more efficient initial fermentation:

• Makes better use of available sugars
• Preserves more nitrogen as true protein
• Reduces fermentation DM losses
• Minimises undesirable microbial activity
• Animal performance

Some examples of the benefits of including Lactobacillus buchneri PJB/1 bacteria to inhibit the activities of the yeasts and moulds that cause aerobic spoilage:

• Less heating
• Lower DM losses
• Less physical waste
• Higher energy feed
• Less risk of mycotoxins

An example of an additive containing both of these beneficial bacteria is Ecocool.

For more top tips, explore our silage advice or download our Handy Maize Guide today. 

Contact Ken Stroud for more information on how you can beat bad bugs in maize silage, 07713 197084 or via ken.stroud@volac.com