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Gerald M. (Jerry) Jones Professor and Extension Dairy Scientist Virginia Tech, Blacksburg
..... .. Harvesting and storing silage at the correct moisture content is the best way to prevent seepage and subsequent pollution. The moisture contents that cause the least seepage also produce the best quality silage. For a bunk silo, this range is 68-70% moisture or 30-32% dry matter. The microbial activity in high moisture silage involves yeasts, fungi, and bacteria. These can cause high gaseous losses of dry matter. Over extended periods, high moisture feed becomes less palatable and is frequently inedible, and it may become toxic. Forages containing more than 74% moisture (less than 26% dry matter) are subject to clostridia fermentation which results in a feed that is less palatable and of poorer quality. A goal to shoot for would be 65% moisture or 35% dry matter. Crops can be too dry when harvested. The ideal moisture content for corn is 65-70%, or 30-35% dry matter. The corn plant has its maximum energy content and yield when the milk line in the kernel has moved from 1/2 to 2/3 down into the crown. Drier plants and late harvest cause dropped ears, stalk breakage and leaf loss so less dry matter is recovered and packing in the silo is more difficult. The first cutting of alfalfa should be done at the bud stage and subsequent harvests made at the 1/10th bloom stage or every 35 days. Alfalfa should be wilted for approximately one day and this should reduce the moisture content by 10%. As much as 75% of the protein fraction is lost as non-protein nitrogen without wilting. Haylage with 60-70% moisture or 30-40% dry matter should have little seepage. Forage with less than 50% moisture (over 50% dry matter) is too dry to ensure good packing, thus increasing the risk of heat damage. Rye should be harvested in the boot stage and wilted. Barley, wheat and oats should be harvested as direct-cut silage when in the soft-dough stage (when the head is filled and the kernels are soft and easily crushed). At this stage, the moisture content should be approximately 65-70%. Moisture or dry matter contents can be tested on the farm with either a moisture tester or a microwave. It is recommended that filling silo begin when the moisture content is approximately 70%, especially if it takes more than one day to fill and seal the silo. If the moisture content should fall below 60%, over 40% dry matter, a shorter length of cut is essential to minimize the presence of air within the hay crop silage or haylage. Corn should be harvested with a 1/4" theoretical length of cut. A finer 1/8" may be desirable only if corn is harvested beyond hard dent stage to make packing easier. Finer chopping leads to greater problems with acidosis, low milk fat content, and abomasal displacements.
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