With ethanol-driven corn prices still above $3, it's time to take your corn silage management skills to an even higher level to optimize this valuable feedstuff.
It's no secret that maximizing the forage portion of a dairy or beef diet can reduce off-farm feed inputs. And quality forage starts before harvest — as in right now — and continues through silo feed-out.
“This is the year to make investments and pay attention to all the details we traditionally talk about in corn silage production,” says Greg Roth, extension grain crops specialist at Penn State University. “Even though we talk about these things every year, they don't always get done, which leads to less-than-ideal silage.”
It all starts with chopping at the right time. “If you miss harvesting during optimum whole-plant moisture (65-68%), then you miss the opportunity to maximize forage quality,” says Bill Seglar, livestock nutritionist with Pioneer.
We enlisted some of the brightest minds in corn forage nutrition and management where silage is grown — from New York through Wisconsin and out to Washington — who offer these tips to help you chop and store stellar silage.
- Predict harvest
The basic rule of thumb is 35-45 days after silking, but you should always walk your fields because hybrids mature at different rates.
If corn is drought-stressed, test moisture earlier and more frequently because the crop can be much drier than it appears. Be careful not to harvest prematurely, because corn with ears and some green leaves might still resume growth and accumulate dry matter. Also, watch for higher nitrate levels. That can happen if excessive nitrogen was applied and the crop is chopped within three days of a rain.
- Moisture-test numerous whole-plant samples
Check several samples from each field during the dry-down process to fine-tune harvest timing.
Don't bank on the kernel milk line rule of thumb to gauge harvest because the suggested per-day dry-down rate (0.5-1% from sample date until optimum harvest maturity) can vary greatly, especially under hot, dry conditions. In fact, university research shows only a 50% correlation between milk-line and whole-plant moisture.
To begin to create optimum corn silage in bunkers, piles or bags, you must harvest between 65 and 68% whole-plant moisture. Aim for a little less moisture for tower silo storage.
- Repair and prep your silos
Remove all old forage and weeds. Examine and repair silo walls and seal cracks, as even a little air penetration causes costly silage loss. In tower silos, check for rotted doors and seals, make sure staves are sound, check the distributor for proper working order and make sure there are no air leaks.
- Schedule a harvest crew meeting
Make sure everyone involved understands the quality requirements. Chopper settings must deliver desired kernel and plant processing. The packing effort must keep up with harvest tonnage per hour. Forage and packing quality must also be checked throughout harvest.
Make sure packing tractors are heavy and you have enough of them to keep up. At harvest rates greater than 100 tons/hour, you might need more than one packing tractor.
- Review packing practices
Pack the bunker silo at a recommended density of 15-18 lbs dry matter/cu ft. Check your current corn silage density to see if you have met this goal or if you need to make improvements for this year.
Match your tractor weight, the time spent packing and the prepacked silage layer thickness (less than 6") to the tonnage delivery rate per hour. Higher-density packed silage gives you more tonnage stored and less dry-matter loss. For example, you can lose 20% dry matter during a six-month feed-out time if your density is 10 lbs/cu ft, but a density of 22 lbs will yield only a 10% loss.
6. Review silage covering
Stored corn silage exposed to water seepage can undergo a second fermentation that can diminish feed intake, lower energy content and inhibit milkfat synthesis. Be ready to cover the sidewalls and top with a 6-8 mil polyethylene plastic and split tires/gravel bags, or an oxygen barrier system such as Silostop, in a timely and efficient way.
Use enough weighting material so plastic will not billow in the wind. A bunker silo should be filled and covered in three days or less. The plastic must be tight against the silage and sealed around the bunker edges so water drains away from the silage.
7. Optimize crop processing
Check your first load of chopped corn silage, and again throughout harvest. Throw silage in a bucket half-full of water so corn kernel pieces sink to the bottom. Remove the floating forage on top (check fiber length), then examine corn pieces to make sure they are properly processed.
To maximize the energy content of corn silage, adjust your processor so it damages 90% of the kernels and pulverizes the cobs.
Cutting height: Determine whether higher tonnage or higher quality is more important and cut accordingly. When chopping height is raised from 6 to 18", the quantity of silage dry matter is reduced about 10%, but estimated milk per ton increases because the fibrous and less digestible lower stalk is left in the field.
Length of cut: The optimum theoretical length of cut (TLC) varies by crop maturity stage, whole-plant moisture and whether the crop is processed. In most situations, the recommended TLC is ¨ö-¨ú" with a processor; ¨ù-¨ü" without one.
8. Use an inoculant
To optimize fermentation, preserve quality and minimize losses, use a quality inoculant based on how you store and feed out your silage. A litany of products is available, so the best advice is to choose a product backed by sound research.
Homofermentative inoculants drop pH quickly to improve dry-matter recovery by 2-3% compared to heterofermentative products, and can improve animal performance by 3-5%, with a downside of possible heating during feed-out.
Heterofermentative (Lactobacillus buchneri) bacteria stop heating and spoilage for long bunk life, and improve aerobic stability at the cost of a somewhat reduced dry-matter recovery compared with a homofermentative inoculant.
9. Proper feed-out
Optimum feed-out rates happen when bunkers and piles are sized properly, so size before filling.
Maintain a good, solid and clean face without disturbing the layers behind the face; a defacer accomplishes this best. Remove 6" in winter and 12" in summer from the face every day. At the end of the day, make sure all loose silage is removed, and take any spoiled silage away from the pile.
Corn Silage Resources: