The stakes are higher than ever for dairy producers choosing corn silage hybrids, says Joe Lauer, University of Wisconsin extension corn agronomist.
“It's a very big and important decision, and you need to spend some time making it,” says Lauer.
That's because the decision can have a big impact on profitability. In University of Wisconsin silage hybrid performance trials, the average difference between the top- and bottom-performing hybrids is about 8,000 lbs of potential milk production per acre, Lauer reports.
That gap has widened in recent years because hybrids have become more divergent. Some of today's hybrids were bred with stover and/or grain characteristics that impact their silage performance. In particular, high-yielding hybrids with greater NDF digestibility (NDFd) can produce more milk per acre and per ton.
They've caused Lauer to rethink his silage hybrid selection recommendations.
“Yield used to be the most important,” he says. “But the development of hybrids with unique NDFd traits has changed hybrid selection to quite an extent.”
Grain yield is still important because grain is very high in energy. But with high-NDF hybrids, stalks and leaves are major energy sources, too.
“The goal is to get as much energy intake as possible into that dairy cow,” says Lauer. “And I don't think the cow cares if it comes from the grain or the stover.”
Most high-NDFd hybrids are considered “normal,” but can be harvested only for silage. In the Wisconsin silage trials, normal hybrids as a group have outperformed hybrids with specific genetic traits. Individual specific-trait hybrids sometimes excel, but overall they haven't done as well as normal hybrids, Lauer reports.
Within the group of normal hybrids, Bt corn has performed above average, producing more milk per acre and per ton.
“I think the reason is that we tend to have a little better grain yield with Bt hybrids,” says Lauer.
Grain yield also impacts the silage performance of Roundup Ready hybrids, but in a negative way.
“If you look at grain trials throughout the country — Wisconsin is no exception — as a group Roundup Ready does not perform as well as a well-adapted normal hybrid, nor as well as a good Bt hybrid.”
Here's how other hybrid types have performed in the trials since 1995:
Brown midrib (BMR): Very digestible, they rate high for milk production per ton. They'd likely be wise choices for dairy operators who contract with neighbors to produce and deliver silage.
But grain and stover yields don't match those of normal hybrids, so milk per acre is lower. There also are agronomic concerns, such as standability.
However, Lauer is seeing improvements in hybrids with this trait.
“The new BMR hybrids seem to be better-performing,” he says.
Leafy: Of all the groups, these hybrids are the most variable, says Lauer. Overall, they produce a little more stover than a good normal hybrid, but slightly less grain.
“Because there's less grain in the silage, the milk per ton goes down. But the tonnage is high, so the milk per acre stays above average.”
High-oil and waxy: These two grain types are about equal for silage, and about on par with normal hybrids. High-oil hybrids have 3-5% more oil, and thus more energy, in the kernels, and the starch in waxy corn kernels is 100% digestible instead of the usual 95%.
In both cases, the impact of these grain traits on silage is small.
“It's hard to pick up differences,” says Lauer.
NutriDense: These are said to offer several quality benefits, including softer kernels for improved silage fermentation.
In limited testing, they've performed about the same as high-oil hybrids, Lauer reports.
He tells growers to look for hybrids with the best combination of yield and quality. Information on both is available from seed companies and universities. Use university and seed company data to narrow your choices to 10 or so high-yielding, highly digestible hybrids with the maturity and agronomic traits you need.
“If you get one in that top 10 group of hybrids, not necessarily the top one, you're probably doing pretty well,” says Lauer. “And that's where you want to be.”