For a dairy producer, the right hay makes milk and money.
But not all hay is equal.
Yet, some in the industry are stuck in a rut when it comes to scoring forage quality, said Duarte Diaz, associate professor and dairy Extension specialist at the University of Arizona
“Our current way of assessing and evaluating quality forages is not good,” Diaz said during an Alfalfa U event this winter. “If we are going to have a conversation about increasing forage quality, we need to make assessments dedicated to capturing that.”
For years, relative feed value, or RFV, has been the ranking tool for measuring forage quality. It incorporates acid detergent fiber, or ADF, to measure energy and neutral detergent fiber, or NDF, to estimate intake.
But it’s not a good measure of quality hay, said Diaz.
“We have been stuck on RFV, relative feed value, for way too long,” said Diaz, adding the test “is a low significance of value to the dairy industry.”
Not all fiber is created equal in terms of digestibility, he said, which is a deficiency in RFV scoring.
But another value tool, relative forage quality, or RFQ, does.
RFQ was developed by University of Wisconsin researchers as a better way to estimate hay quality. Diaz said he is trying to bridge the gap between the growers and the dairy producers.
“We are so focused on RFV because that is the number everyone understands and knows,” he said but added that RFV can’t capture everything. “That becomes more significant as the value of the hay increases.”
RFV or RFQ?
“I don’t want you to leave this room and say Dr. Diaz said RFQ is the way to go,” Diaz stressed. “I just want you to realize RFV is not the way to go.”
RFV, after all, has been useful for several years to compare the quality of legume and legume/grass hay and silages. Diaz said having one index to price hay and predict animal performance has been useful for both livestock producers and hay growers.
The index ranks forage relative to the digestible dry matter intake of full bloom alfalfa.
“The RFV value has been a powerful tool,” Diaz said. “However, we need to start to transition away from that because it is not accurately estimating how the animal is actually going to utilize the material.”
During his presentation, Diaz noted RFV’s limitations:
• Digestible dry matter and dry matter intake are assumed to be constant for all forages;
• ADF and NDF are the only laboratory values used in calculations; and
• Crude protein concentration of forage is not used.
The fiber from grasses and legumes naturally differs in digestibility, as it is grown under different ambient temperatures, Diaz said. The RFV of first-cutting alfalfa will be similar to second and third cuttings harvested at similar stages of maturity.
However, fiber fraction digestibility could vary as it is influenced by the ambient temperature at time of growth and development, he noted.
RFQ takes into account fiber digestibility to estimate intake, as well as the total digestible nutrients, or energy, of the forage, said Diaz.
The RFQ Index is an improvement over RFV index for those that buy and sell forages because it better reflects the performance that can be expected from the cattle. It also differentiates legumes from grasses.
Producers weigh in
Diaz said the industry continues to make forage quality improvements, such as with low-lignin, or, as Diaz calls it, high digestibility alfalfa. However, RFV is an inadequate test, including for improved digestibility.
For instance, he said, a 10 percent increase in digestibility can increase milk or beef production.
For every 1-pound increase in dry matter that a cow consumes, there is enough energy potential to produce an additional 2.5 pounds of milk, Diaz said.
There are some limitations of RFQ, he said. It’s not perfect. But it allows you to capture the digestibility differences.
The industry appears mixed on what test to use.
Eric Larsen, a panelist at Alfalfa U in Ogden, Utah, said in 2017, his operation near Blackfoot, Idaho, produced 95,000 3-by-4 alfalfa square bales both on their farm and on a custom basis. The alfalfa goes through a broker and most use RFV.
“But as we get into the new technology and low lignin, RFQ is going to play a bigger role,” he said, adding, “it’s hard to convince guys to go RFQ” who have been using RFV for years.
Mike Schuppe, who grows 1,000 acres of alfalfa and manages an irrigated grass and forage and custom hay operation near Iliff, Colorado, said his farm uses RFV because that is what the customers ask for.
Some dairy producers might like RFV better, but Kendel Davis, an organic and conventional alfalfa grower near Center, Colorado, said he prefers RFQ to get the best analysis of his hay quality. For his operation, he uses both tests.
But not all want to see test scores, he added.
“I have a lot of guys who say they don’t care about the numbers, they just want to see” the alfalfa, he said. “They have been in the industry a long time, and they know a good bale of hay when they see it.”
It’s a conversation that will continue for a long time, Diaz said.
“For me, it is pretty interesting, we have gone this far, and we are still at this point where we are comparing apples to oranges,” he said. “But I think that is where the rubber hits the road—doing a better job of capturing the value of all these technologies.
“You are putting in the effort to put it in on the ground and take care of it,” he added. “If we don’t capture that, that is a big shame.”
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