Harvesting at the right time
In a dairy forage seminar at World Dairy Expo, Dan Undersander, research and extension agronomist with the University of Wisconsin, stated, “In either hay-making or silage-making, we cannot make the product any better.
The best we can do is preserve what we cut. If you cut it late at low quality, there’s nothing we can do to make it better at that point, so the key thing is to get in there and cut it on time.”
Grasses should be cut at the boot stage when the head is just coming out of the whorl, at least for first cuttings. The target to achieve is 10 to 15 percent water-soluble carbohydrates in the dry matter, which is basically young, leafy grass.
When grass is well-fertilized and rapidly growing, it tends to have more of those starches and sugars being put into growth and less accumulation, so that’s why we want to harvest at about the boot stage.
However, because second cuts and third cuts do not have heads but are strictly leafy materials, it’s recommended to let the grass get to 12 or 15 inches tall, cutting by height rather than calendar days or maturity expectation.
On a second-cutting or third-cutting stand, after the 12-inch to 15-inch growth point, the leaves quit growing, the bottom leaves die off and disease sets in.
Cool-season grasses will not grow heads again after the first cutting or in a seeding year (with the exception of ryegrass).
Undersander says the current cutting height recommendation for grass is 3½ to 4 inches, which is taller than alfalfa because grasses store energy in the base of the stem instead of the roots.
The taller cut heights also reduce dirt contamination. Internally, grasses have about 4 percent ash.
Undersander stated an average analysis, based on forage-testing haylage samples recently reviewed at the University of Wisconsin, had 10 percent ash, which means 4 percent was due to internal plant ash and 6 percent was added from the harvesting process. And, to put it bluntly, cows won’t milk much eating dirt.
Wide swath
Another thing to remember during harvest is to make a wide swath. For cut grass to dry rapidly, it needs to be spread out over the entire cut area.
A lot of the newer conditioners will only cover 40 to 60 percent of the cut area, so too much hay lies on top of itself and insulates itself, thus preventing drydown. If a wide swath is used, then silage could reasonably be made either at the end of the same day it’s cut or the next morning.
A wide swath is what keeps the stomata open so moisture can escape. In addition, cut forage put down in a wide swath intercepts more sunlight, encouraging drying.
The drydown
If we were trying to dry a bundle of clothes without a dryer, we’d hang them out in a single layer to dry on a clothesline. We certainly wouldn’t bend them four or five times, then wad them up and throw them on the ground in a pile and expect good results.
Undersander states the same principle applies to drying forages. Yet sometimes producers bend stems four or five times (conditioning), pile it in a windrow and think they’ll get a good product.
For grass forages, both conditioning and wide swaths must be used to aid faster drying. Tedding can also help with the drying process.
During the raking process, rakes need to be adjusted to not touch the ground if using a power rake and minimally for a ground-driven wheel rake.
If you can see scrapes in the dirt from the rake tines, then it’s adding a lot of dirt and stones to the product.
If the grass is cut at the right height and spread into a wide swath, the grass stays above the ground on the stubble, and the rake doesn’t have to dig into the ground to lift the grass like it would with a windrow that sinks to the ground.
Inoculants
Now that it’s cut and you’ve allowed it to dry to around 60 to 65 percent moisture, it’s time to chop it. At this point, you’ll need to decide on an inoculant because if you apply the inoculant as it goes into the chopper wagon, you’ll get better coverage.
Undersander encourages growers to remember that applying inoculants is a lot like spray painting: It stays where it lands and doesn’t move through the silage, so it’s important to get good coverage and that’s why it’s most effective when applied at the chopper.
The Lactobacillus (LAB) plantarum inoculant is effective on grass silage, with about a 70 percent response which, although 100 percent would be better, is still well worth it.
The inoculant is key to the conversion of sugars to lactic acid. But it’s only as good as its application. LAB should be used at the rate of 100,000 colony-forming units per ton, and the coverage goal should be to apply it to every side of every chopped leaf.
Hence, it’s better to apply it at the chopper than on top of a windrow or at the bunker where it would only land on the topmost surface.
The much-discussed Lactobacillus buchneri inoculant could be beneficial to grass silage from a feedout standpoint.
The net result is that silages inoculated with L. buchneri are more resistant to heating at feedout when the silage face is exposed to air. If the silage has been well-packed at 45 pounds per cubic foot and the bunker or pile has a straight face, then L. buchneri probably isn’t necessary.
Undersander says, “Some are using a combination [of LAB and L. buchneri]. But if you’re feeding a bale in less than a day, you don’t need L. buchneri.
In a silage pile, if you’re taking a foot off the face in a day and it was packed well, then you don’t need it. I encourage people to pack well and just use lactobacillus plantarum.”
Packing the pile
Ideally, a bunker should be filled within one or two days and then covered with two layers of plastic. Baleage should be wrapped within three to four hours.
As soon as the bale is wrapped, the temperature starts to fall because the oxygen is cut off, which is the goal.
Packing silage in the pile, bunker or tube is one of the most crucial steps to preserving quality. We cannot overpack, and keeping the packing tractors running and managing the labor schedule so packers don’t stop for coffee breaks or dinner will result in a better pile.
Good compaction gives faster fermentation action and less spoilage on feedout. If we pack well, then when the face is open for feedout, oxygen won’t move as far into the pile.
Packing density recommendations are the same for grass, alfalfa and corn silage, at 15 pounds dry matter per cubic foot, which is 45 pounds silage per cubic foot if you’ve achieved 65 percent moisture.
If a pile is adequately packed, and you punch it with your hand, you can feel a hard surface. If you punch it and your hand goes in an inch or two, it’s too soft and oxygen can enter the pile.
There are some options that will aid in pile compaction: You can slow down the fill rate until packing tractors have adequate time to compact the pile, add more tractors, add tractor weights or spread at a 4-inch depth instead of 6-inch depth.
Covering the pile
After the silo or bunker is packed, cover it with two layers of plastic, making it airtight, and put weights on it so it doesn’t blow away. Line the bunker walls with plastic as well – they get cracks and holes in them over time and this will prevent oxygen from entering the pile.
Make sure the top of the silage in the bunker doesn’t dip downward next to the wall so water doesn’t pool up in the depression and seep into the pile.
Good face management practices for grass, alfalfa or corn are all the same. Maintain a straight face and use a facer that scrapes from the top down.
Don’t go in with a loader and lift up – because if you do, it opens the face for oxygen to permeate the silage. Face management is key to quality forage at feedout.
While there are a lot of commonalities between grass silage, and legume or corn silage, there are differences, which include choosing the right time to harvest, management practices to get it dry enough and chopping it to a little longer length than you would for other forages. FG
