Harvesting maize silage at 30-38 per cent dry matter ensures enough moisture for quality fermentation. Healthy maize plants continue to produce sugars storing them as starch until physiological maturity (black layer).
Research conducted by Pioneer in conjunction with the University of Illinois shows starch can increase by over 25 per cent from ½ milk line to black layer.
Advances in plant breeding mean growers are not sacrificing fibre digestibility by delaying harvest to this point, provided plants are healthy.
Harvesting at the higher end of the window (36-38 per cent dry matter) will likely boost starch content, but must be weighed against weather-related and contractor availability risks.
Cutting and processing
Maize silage is usually chopped between 12-20 mm, but there’s no single ideal chop length.
It depends on feeding plans and other ration ingredients.
If the silage is wet or will be fed in low effective fibre and or high starch or sugar rations, use a longer chop.
For drier silage, or when fed with high effective fibre or low-carbohydrate rations, chop shorter.
Kernel processing is vital, as breaking kernels into at least four pieces boosts starch digestibility both in the rumen and throughout the digestive tract.
Using a proven maize silage inoculant
Microbial populations on maize at harvest greatly affect silage quality and stability.
Temperature, humidity, solar radiation, plant maturity and moisture influence natural (epiphytic) microbial levels.
Silage inoculants, containing lactic-acid bacteria, such as Pioneer brand 11C33, boost fermentation quality and reduce losses at feedout.
Maize’s high sugars can promote yeast growth at feed-out time.
This can increase dry matter loss, heating and reduce palatability.
Proven inoculants reduce risk and improve fermentation, but they shouldn’t replace good stack management.
Consolidation and sealing
Compact the stack thoroughly, layering no more than 150mm at a time and ensuring enough weight from pack tractors, especially with drier silage.
Finish with a smooth surface and immediately cover with an oxygen barrier film and silage plastic or a heavy-duty silage cover.
Line dirt bunker walls and overlap any joins. Seal the perimeter with sand or lime. Weigh covers down using tyres or sandbags laid edge-to-edge for best results.
Leaving it in the stack
There are numerous feed security, cost and quality advantages to carrying a buffer of maize silage on farm.
The seven-hour ruminal starch digestibility of fermented new-crop maize silage drifts upwards (about two percentage units per month) for about six months before plateauing.
While inoculated maize silage can be fed within a week of ensiling, leaving it in the stack for a minimum of four months will result in significant feed quality gains.
- Pioneer dairy specialists Leighton Hart and Greg Morris
