Pioneer Technical Insight

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The optimum drymatter percentage for ensiling maize silage is 30-38%. However weather conditions in some seasons mean that in practice, some crops will be harvested at above 38% drymatter. This can have implications on both silage quality and how easy the crop ensiles.

The effect of increasing maturity on the yield and quality of maize silage depends on a large number of variables including the hybrid, the plant population and the growing environment. We know that:

• Maize grain yield increases up until the plant reaches physiological maturity (also known as blacklayer). The whole plant drymatter at blacklayer depends on the stover drymatter and the cob-to-stover ratio however it is normally around 42-44%. The increasing grain content has a positive effect on the crop feed value.
• As stover (stalk plus leaf) drymatter increases, feed value of stover slowly decreases due to the decrease of cell wall (NDF) digestibility.
• As the plant matures, yield accumulation is rapid and the feed value increases due to the increasing grain content offsetting any decreases in stover feed value.
• Somewhere between 38% and blacklayer, the increase in feed value due to the accumulation in grain is partly offset by the decrease in stover feed value.
• After blacklayer, feed value and yield decrease due to a loss in the quality and quantity of stover.

The main point to remember is that maize silage feed value changes gradually and a well managed dry crop can still have an excellent feed value. One of the main problems with a dry crop is achieving adequate compaction to ensure a good fermentation and minimal aerobic (oxygen present) spoilage at feed-out time.

The following guidelines will aid in achieving a successful fermentation of dry maize silage crops.

1. Reduce chop length. A fine chop length releases more plant fluids. Crops that are over 38% drymatter should be chopped at 8-10 mm theoretical chop length.
2. Ensure your contractor runs a plant processor. As the kernels become more mature, they are more likely to pass through the cow undigested. Plant processing improves kernel starch digestibility by breaking the hard exterior of the kernel, increasing the surface area and allowing better access to the rumen microbes. Aim to have a 99% of the kernels cut into quarters (with a target of min. 80%).
3. Maximise compaction. As drymatter increases a greater consolidation effort is required to achieve a good compaction. The use of more vehicles, heavier vehicles, a greater rolling time or a combination of these factors is recommended. Make sure that the maize silage is spread into thin layers, which are easier to compact.