Evaluate corn hybrids for silage a little differently than you would for grain, says Jim Paulson, University of Minnesota Extension dairy educator. Both should be considered for their agronomic traits and relative maturity ratings, but silage-corn hybrids should be evaluated for silage yields, whole-plant digestibility and neutral detergent fiber digestibility (NDFD).
Each component of whole-plant silage, typically 40% grain and 60% stover, affects digestibility. “Of the stover portion, the stem holds the most dry matter, followed by cobs and husk, then leaves. Don’t be misled by high-grain hybrids that might have greater whole-plant digestibility but not adequate NDFD. Look at NDFD and lignin percent of NDF,” Paulson warns.
As you compare forage test results, keep in mind that NDFD is identified using either a 30-hour or a 48-hour in vitro test, he adds. “Many are going to the 30-hour report because it more closely predicts performance in the milking cow. However, 48-hour digestibility numbers will be higher. I like to shoot for over 60% NDFD with the 30-hour number.”
Also look at the relationship between milk/acre and milk/ton potentials, he adds. For high-producing dairy cows, greater emphasis should be placed on milk/ton than for other livestock classes. For dairy, choose hybrids in the upper right corner or at least on the right side of the chart (below). Then look for hybrids that have performed well at multiple locations for both milk/acre and milk/ton. Within your group of hybrids, then choose on price, agronomic traits, or other criteria important to you.
“Finally, remember that many variables affect your success; from the growing season all the way to proper harvest management,” Paulson says. 