RFQ forage testing delivers better quality estimates
Although fewer than 10% of forage growers use relative forage quality (RFQ), the quality index developed eight years ago to include fiber digestibility measurements, its use has steadily increased, says Dennis Hancock, University of Georgia Extension forage agronomist.
“But it still doesn't get the respect it deserves,” he adds.
Forage growers are finding that RFQ — vs. the old relative feed value (RFV) index — more accurately categorizes hay into animal production classes. As a result, RFQ is a better tool for setting hay prices in markets where there is a diversity of animal systems and forage species.
“RFV is still a great metric to compare, for example, one alfalfa lot to another, but it isn't as robust as RFQ at comparing hay lots from different species,” Hancock says.
“This is one of the beauties of the RFQ system. We're able to compare different hay crops against one another and this strengthens one's ability to categorize and market hay in value classes. That's much more difficult to do with many of the other metrics that we use to compare one species to another.
“Like RFV, it predicts dry-matter intake. But unlike RFV, RFQ actually compensates for the differences in the species by using a TDN calculation that is specific for either grasses or legumes. Consequently, RFQ gives us a fairly good number to compare one species to another.”
To maximize your crop's RFQ score, use the highest-quality forage species that can be grown in your area and then harvest them at correct maturities or harvest intervals and at the proper cutting heights. In the Southeast, cut alfalfa in spring at the bud stage and subsequent growth at late bud or 10% bloom, the forage agronomist recommends.
“Our alfalfa recommendations in the Southeast may be a lot different than they would be in Wisconsin or anywhere else,” he cautions.
For orchardgrass, ryegrass, fescue and other cool-season grass species, cut at the boot stage when the seedhead begins to emerge and thereafter when the crop has 10-12" of regrowth. To optimize quality from bermudagrass, cut at 25- to 28-day intervals.
“Of course, it is important to avoid cutting if significant rainfall is predicted during curing,” says Hancock. “However, the fear of rain damage can lower forage quality much more than rainfall actually does. A week delay in harvesting some forage crops to avoid a ½" rain may result in a larger decrease in TDN and RFQ than the rain would have caused.”
Alfalfa growers should target RFQ scores at or above 150. Other legumes, cool-season annual and perennial grasses, summer-annual grasses and bermudagrass should generally produce RFQ values between 100 and 150.
Hancock also advises growers to protect the quality of their hay from the elements, covering it with tarps, barns or hay sheds. Fertilize as needed, based on soil-test results.
More growers are starting to realize the value of RFQ, says Dan Undersander, the University of Wisconsin Extension forage agronomist who was instrumental in developing the quality index.
“RFQ is quite universal and is already being used widely today,” he says. “Dairy farmers use it. Beef cattle producers use it, horse farms, too, so it only makes sense that suppliers will be using it. It's used from California to Oregon to Texas, Indiana and across the Southeastern states.”
The importance of RFQ testing and why it should be used lies primarily in good agronomic practices that will result in high-quality forages, the two experts maintain.