Selection of corn hybrids for silage production is confusing at best, says Mike Allen, Michigan State University extension dairy nutrition specialist. “It used to be much easier. We simply chose the hybrid with the highest grain yield for both grain and silage.” However, it’s now known that other important factors related to corn silage affect farm profitability. And that simply selecting corn silage hybrids with highest grain yield will not necessarily maximize profit for your farm.
For instance, forage yield — composed of the grain plus non-grain parts of the corn plant — is more appropriate that grain yield alone because there is considerable variation in yield of the non-grain fraction among hybrids, notes Allen. Hybrids with the highest grain yield do not always have the highest forage yield. Forage quality factors, like neutral detergent fiber (NDF), protein and energy concentrations, and NDF digestibility, also vary considerably among hybrids, and most important, quality factors are not related to grain yield.
Consideration of forage yield, as well as multiple quality factors, makes corn silage hybrid selection difficult.
The introduction of selection indexes like milk per acre and milk per ton have been helpful. But you must keep in mind that all selection indexes have underlying assumptions, and the usefulness of an index depends upon how broadly the assumptions apply to your farm, cautions Allen.
For example, milk per acre is a selection index that combines yield and quality into a single term, allowing easier ranking of forages and hybrid selection. Allen asks that you consider the following points regarding this tool:
- Milk per acre assumes that corn silage cost is less than corn grain and that cropland is limiting.
- These assumptions often are not correct and bias the selection of corn silage hybrids toward those with high grain content and high yields.
- However, corn grain is often less expensive than corn silage, especially after silage shrinkage and spoilage are considered.
- The number of cows supported by a given acreage is extremely variable, greatly diminishing the value of using milk per acre as a broadly applied management tool.
- Milk per acre does not consider the effects of forage quality on milk yield per cow, which often has a much greater impact on farm profitability than corn silage energy yield per acre.
- No selection index can adequately rank corn silage hybrids for most farms.
- A much better approach is to use partial budgeting to compute the value of corn silage production and utilization on your specific farm.
For more information, go to: http://www.msu.edu/user/mdr/archives/mdrvol10no3.pdf
Michigan Dairy Review