Since the French farmer Auguste Goffart published his book about ensiling green corn in 1877, corn silage has become one of the most used ingredient in the dairy industry. Corn silage is a good source of both energy and effective fibre, and an excellent forage for dairy cows. The nutrient composition of corn silage reported by a commercial laboratory in New York (+250,000 samples) was 33.7% dry matter (range 24.4-43.0), 8.2% protein (7.2-9.3), 43.6% fibre (NDF; 37.7-49.6), 31.8% starch (24.3-39.3), and 70.4% (45.1-95.6) starch digestibility, which is measured in vitro after seven hours of incubation in rumen fluid.
During the fermentation process of corn silage some nutrients remain stable while other change significantly. Researchers from University of Wisconsin evaluated the effect of ensiling time on ruminal in vitro fibre and starch digestibility in corn silage hybrids. These authors showed that while fibre digestibility was not affected by ensiling time (55.9% NDF digestibility at 30 h), gradual increases were observed for starch digestibility (61.7, 71.5, 79.0, and83.8% of starch for 0, 30, 120, and 240 days of storage, respectively). Similarly, based on data from almost 15,000 samples, a commercial laboratory from Maryland reported starch digestibility changes over time during the first 27 weeks of fermentation from 62.3% in the fresh silage (week 0) to more than 76.0% after 18 weeks of storage (Fig. 1).
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