By Ben Beckman and Jerry Volesky et.al
Silage harvest for fully irrigated full-season corn usually begins 45 days or 800 GDDs after the tassel/silking growth stage. However, growing conditions and the season length of the plant itself can make predictions based on the calendar fuzzy at best.
Accurately assessing whole plant moisture is key to proper silage pile fermentation and tight packing. If silage is too dry, packing is difficult and may allow oxygen into the pile, causing overheating, mold/yeast/bad microbe growth, and spoilage. When the silage moisture content is too high, piles can weep with valuable energy and nutrients flowing out as a loss from the pile. Also, damaging clostridia bacteria colonies can grow when silage is too wet. Target silage storage moisture content should be 65-70% moisture.
Another factor to consider for silage chopping is milk line (a corn kernel starch content indicator). Starch is one of the most energy-dense feed components, so silage that contains higher amounts of starch will be higher energy overall.
Source : unl.edu