The information presented in the following tables is intended to help producers select corn hybrids which produce large yields of high quality silage. Consistently high yields over several locations and years reliably show a hybrid's ability to produce top yields. Primary quality factors are the proportion of grain and the digestibility of the grain and non-grain portions of the hybrid. Hybrids differ in the proportion of grain they produce.
In the past it was accepted that a hybrid with the highest proportion of grain made the highest quality silage. Research has shown that many times this is not true. In-vitro dry matter digestibility (IVDMD) is a measure of the percentage of a feedstuff the animal can digest and utilize. IVDMD values for grain are high and do not vary greatly among hybrids. IVDMD values for the non-grain portion (fodder) of the corn plant are lower but much more variable among hybrids compared to the grain portion. Thus, one hybrid with a lower proportion of grain could have high quality (digestibility) because the IVDMD of its fodder portion was much higher than another hybrid having a higher proportion of grain but a much lower IVDMD of its fodder portion.
The yield and IVDMD of the whole plant (fodder and grain) should be considered when selecting a hybrid to produce silage. Some dairy farmers may be tempted to sacrifice yield and use a hybrid with a very high proportion of grain to increase the digestibility (energy density) of the silage. Feeding such high grain content silage plus the concentrate feeds usually fed can overload the rumen with starch and lead to serious acidosis and associated health problems plus abnormal composition of milk produced. The most desirable silage hybrids for dairy cattle should produce top yields of highly digestible silage. To obtain this high digestibility and maintain high silage intake and normal digestive function, emphasis should be directed to high digestibility of fodder with a lower proportion of grain rather than trying to obtain high digestibility by maximizing the proportion of grain.