When we harvest silage, regardless of the crop type, we need to aim to harvest at a dry matter (DM) percentage between 30% and 40%, with an optimal of 35% DM. At this maturity stage, there is enough moisture in the plant material to enable proper primary fermentation and compaction. At a DM % below 30%, we run the risk of leaching or clostridial fermentation, with the most soluble nutrients in the silage being lost first. Above 40%, we will have difficulty in compaction, leading to increased exposure to oxygen, which could result in aerobic instability at feed-out.
The correct theoretical length of cut (TLC) for each silage type is a function of what is required on farm in terms of effective fibre. If we need more effective fibre from the silage, we can cut slightly longer than the ideal of 13mm-15mm. The longer TLC aids in providing the scratch factor in the rumen aiding in proper digestion. We need to be cognizant of the fact that we can take the TLC down to 8mm. A TLC below 8mm will result in no contribution in terms of effective fibre from the silage component in the final diet. We refer to this as “silage fit for purpose”.
Maize kernel and plant processing are key determinants in the quality of the silage we feed. Up to 82% of the maize kernel’s weight is starch, and we need to ensure that it is available to the ruminant to effectively utilise and digest. Maize kernels broken into halves are considered processed. An easy way to check this is to take a 1 L cup and sample the silage. Ideally, we would like to find no whole kernels in this sample. If we find more than five whole kernels, the sample is not processed. This is usually the case of the corn cracker not functioning as it should or some teeth that are damaged or broken.
How to harvest for high quality silage