If you think benchmarking of forages doesn’t start until you’re ready to feed them, you’re missing half the value.

Case in point. A Wisconsin dairy producer was spot-checking particle length and the amount of kernel processing during corn silage harvest. While the test results from the first load from each chopper were right on, a spot check one-third of the way through a 700-acre harvest revealed that the kernels were relatively unscathed. Harvest was stopped. Examination of the chopper revealed that a bearing in the roller mill, which processes the corn, had stopped working. And, no warning lights had gone off to alert the custom operator of the problem.

  “If you don’t catch a problem like this during harvest, you are stuck with what is in the bunker for the year,” says Lynn Davis, of Nutrition Professionals, Neenah, Wis.  That’s why Davis recommends to his clients that they perform benchmarking tests before and during the harvest of all corn silage and alfalfa. Making sure you have a quality product going in helps ensure that you get quality coming out of the bunker, too.

Here’s how to use benchmarking to improve the quality of forages on your farm.

Before harvest

Everyone knows that moisture level at harvest is critical for proper fermentation, but it’s amazing how many times “we miss the mark,” says Davis. Getting a proper read on when to start harvest — for both alfalfa and corn silage — is huge. To do so, you must consider plant maturity and moisture content.Benchmarks to use:

  • For alfalfa.Use a Koster tester or microwave method to test the moisture content of your alfalfa before chopping. The dry matter content must be greater than 35 percent and less than 50 percent for good fermentation.
  • For corn silage.Don’t rely on milkline to judge harvest readiness, says Jon Erickson, district agronomist in Wisconsin and Minnesota with Mycogen Seeds. Because of the stay-green characteristics in some hybrids, variability in kernel dry-down and environmental effects, it’s difficult to judge moisture content by visual observation alone. Instead, look at plant maturity and moisture content. To get an accurate measure of whole-plant moisture, select a few stalks and chop them into small pieces (a chipper/shredder works nice) and test for moisture content. Do this for each hybrid planted, and then harvest in the order that will yield the best silage. Remember, corn standing in the field can dry about 0.5 percent each day. Target your harvest for when corn plants are 30 percent to 35 percent dry matter if going into a bunker, and 35 percent to 38 percent dry matter if going into an upright silo. For brown mid-rib (BMR) varieties, harvest at 30 percent to 34 percent dry matter if going into a bunker, and at 32 percent to 37 percent dry matter for upright silos.

At harvest

Alfalfa can be a big challenge. When you take three to five cuttings each year, Mother Nature has that many chances to interfere with your best-laid plans. Although corn silage carries less risk — one crop, one harvest — many things jeopardize your forages at harvest. Benchmarks to use:

  • For alfalfa.As the season progresses, each alfalfa cutting becomes less digestible due to heat stress, says Dan Undersander, extension forage specialist at the University of Wisconsin. So, store each cutting in a separate bag or bunker.
  • For alfalfa.Check particle length when you start chopping. Using a three-shelf Penn State particle separator aim, for:  15% to 25% of particles on the top shelf. 30% to 40% of particles on the middle shelf. 40% to 50% of particles on the bottom shelf.
  • For corn silage. Check particle length and degree of kernel damage when you start chopping and then periodically throughout harvest, says Davis. When using a custom harvester, always check each chopper individually. For particle length, using a three-shelf Penn State particle separator aim for:  10% to 15% of particles on the top shelf. 40% to 50% of particles on the middle shelf. 40% to 50% of particles on the bottom shelf. When using kernel processing, visually inspect the kernels for damage. Ideally, 100 percent of the kernels are knicked, cracked, or otherwise broken into pieces. The drier your forage at harvest, the greater the importance of achieving good kernel damage.
  • For corn silage.Collect and save a representative sample from each hybrid harvested. You will use it to make decisions for next year’s corn silage production later.

In addition to these benchmarks, size your bunkers so you can fill them in four days or less, Undersander says. Remember, during harvest, NDF can decline by 0.5 percent per day. Relative Feed Value can change by five points per day.

After harvest

Once the forages have fermented, it’s time to start testing nutrient content and digestibility to see what you have. (Ideally, you should have enough of last year’s corn silage or alfalfa silage to use while the new crop ferments.) Tests to run include: 48-hour NDF digestibility, particle size/length, and protein. In addition, for corn silage, you’ll need starch content and degree of kernel damage. Benchmarks to use:

  • For alfalfa.Compare ADF to NDF. If the spread between the two is more than 10 points, it could mean that too much grass is creeping into your alfalfa stand, says Undersander. Consider replanting or spraying.
  • For corn silage.Use the test results from the samples of each hybrid that you saved and tested during harvest to judge how each hybrid fared. Plug the numbers into the MILK2000 spreadsheet developed at the University of Wisconsin to determine milk per ton and milk per acre, says Karl Nestor, senior nutritionist with Mycogen Seeds. When making your hybrid selections for next year, select those that score well on both milk per ton (a measure of digestibility) and milk per acre (a yield measure). You also can use test-plot data and the MILK2000 spreadsheet to evaluate hybrids that you didn’t plant.
  • For corn silage.If digestibility is less than you’d like, look at what factors could have been changed during harvest — for example, cutting height. Also, look at what factors could have been controlled better during the growing season. If those factors don’t seem to be the cause of low digestibility, perhaps it’s the hybrids planted. One of the best ways to improve digestibility of your corn silage is to select hybrids that were developed for corn silage, or to plant BMR corn silage hybrids, says Erickson. Research from Mycogen Seeds has shown that the fiber digestibility of silage hybrids is generally 2 percent to 5 percent better than grain hybrids cut for silage. And, with BMR silage hybrids, you gain another 8 percent to 15 percent in digestibility.

Long-term tool

Once you start benchmarking forages, it’s a good idea to maintain those records. That way, you can go back and compare your forages’ past performance with current crop and use that information to help understand why a cutting of alfalfa or corn silage crop may not be feeding out as well. And, on the flip side, it’s good to have benchmark data from when the cows are really humming along. That way, you’ll know what it takes to make that herd consistently shine.

Helpful growing tips

here are a few things you can do at planting or during the growing season to improve the consistency and quality of the forages you produce on farm. The list was compiled with the help of Dan Undersander, extension forage specialist at the University of Wisconsin, and Jon Erickson, district agronomist with Mycogen Seeds.

  • Test soil fertility every three years. Forage crops use more soil nutrients than grain crops do. Potassium gets depleted more quickly, and sometimes extra nitrogen is needed to help boost tonnage while maintaining quality.
  • Use good ground. People tend to use poorer ground for corn silage. But if you want better, more-consistent-quality forages, plant on better ground.
  • Get a good stand. Secondary pests, such as wire worms and seed corn maggots, can reduce your stand substantially. And corn harvested for silage does not make bigger ears to make up for a missing plant like corn grown for grain does. To protect the seeds you plant, apply an insecticide and fungicide at planting, or plant seeds that have been pre-treated.
  • Make good planting decisions. Plant corn silage at the highest plant population for that hybrid on that soil type. Planting a thinner stand does not produce better-quality silage.