A forage tester that can be taken to the field to quickly measure forage dry matter content and nutrient levels is getting high marks for its accuracy, says a University of Wisconsin dairy scientist.
“At least for dry matter, we’re happy with it,” says Randy Shaver, who, with graduate student Matt Akins, conducted trials on it. The machine: Dinamica Generale’s near-infrared reflectance spectroscopy (NIRS) portable unit recently made available in the U.S.
“We sampled both corn silage and alfalfa silage for 11 weeks from our farm at Arlington (WI). We ran those through the NIRS unit and then we also did oven dry matters on those for comparisons. It’s pretty comparable for both haylage and corn silage,” Shaver says.
The Italian-made portable unit is currently available to Mississippi hay growers to determine “when is the best time to cut their hay and preserve quality,” says Rocky Lemus, Mississippi State University (MSU) Extension forage specialist.
He bought the unit using $30,000 in grant funds and says crude protein plus ADF and NDF digestibility data will help growers manage nutrients.
“A lot of producers are applying all fertilizer at once – or they’re not splitting their applications correctly. This information will help us show, based on crude protein, how much nitrogen isn’t there. And if they need to adjust or split nitrogen applications in a different way,” says Lemus.
The unit comes with standard calibrations that users should update using their own samples, Shaver says. That’s a matter of scanning 10 forage samples into the NIRS unit that are also analyzed commercially and then updating calibrations.
Lemus suggests using more than 10 – and including samples from different harvests throughout the year. “That will help to account for any environmental changes that might affect forage production and quality,” he says.
His tester has been calibrated for use on Mississippi forage crops, including annual ryegrass; wheat, rye and oat small grains; alfalfa; annual and perennial clover; bahiagrass; bermudagrass; tall fescue; and summer-annual crabgrass, teff and forage sorghums.
“One of our goals is to be able to develop specific equations for predicting the quality of all of these forage crops,” he says.
Larger farms may be able to afford the cost of the tester, but Shaver believes it will mainly be used by nutritionists, crop consultants or feed stores as a service to growers.
Its passing the test on accuracy may help override the skepticism people have about portable units, says Matt Dobberstein, a Dinamica Generale regional manager based in Hudson, WI.
“Forage testers out years ago didn’t work the way they were supposed to,” he says. “Nobody kept up with the calibrations. But we do calibrations constantly, so the systems are always upgraded every year.”
The tester will also offer relative feed value as one of its chemical parameters in the near future, he says.
More hay growers may see the value of forage testing as they use the unit, Lemus hopes. “I usually try to emphasize to my producers the need to balance quality and quantity of forage production. You have to be able to go in the field – especially in crops like bermudagrass that tend to lose forage quality quickly – and tell a producer, ‘You’re now at the prime of this forage’s quality. If you wait more than a week or so, you start losing quality.’
“It’s real-time information,” he points out. “Usually when you send a sample to the lab, it might take one or two weeks, depending on how busy the lab is, to get that sample back.”
The forage-analysis equipment can also give a cattle producer a more accurate assessment on when to graze a specific pasture based on the quality of the grass, Lemus says.
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