Kendall Guither believes he's found a better way to price his forages according to the value they bring to dairy clients.

For several years, he's had his hay and baleage analyzed for dry matter digestibility, and is convinced it's a more accurate measure of quality than relative feed value (RFV) or relative forage quality (RFQ).

“We're looking at total dry matter digestibility,” says Guither, of Walnut, IL. “Relative feed value is just looking at the fiber. Fiber is the plant cell walls — the ADF and NDF. It doesn't account for the cell contents, which are the protein, carbohydrates, etc.”

He hasn't used RFV for a number of years.

“Relative feed value gives you a very general idea if a feed is better or worse than some other feed,” he says. “It's kind of like a dart target. But the bull's-eye that really tells you how it's going to feed is the digestible dry matter.”

Guither, who makes bale silage and dry hay from 450 acres of alfalfa, says alfalfa normally averages 72% digestible, ranging from 62% to 87%. Most of the 48 samples he had tested last year were over 76% digestible. One bale silage sample tested 86% digestible.

Baleage usually is more digestible than dry hay, probably because it has more alfalfa leaves. He's been pricing it the same as hay, on a 15%-moisture basis. But pricing it based on its digestibility may bring him a few extra dollars per ton.

After numerous calculations, Guither came up with a preliminary pricing formula, and plans to begin using it on his 2006 crop. He'll start with a base price for hay or baleage that's 78-80% digestible, then will raise or lower it for every three- or four-point change.

“If it goes up a little bit, I'll add $5/ton,” he says. “If it goes up quite a bit, maybe I'll add $10/ton. If it goes down a little bit, I'll subtract $5.”

His calculations show that each pound of digestible forage dry matter is worth about 8¢. If a ton of forage is 80% digestible, for example, it has 1,600 lbs of digestible feed (0.80 × 2,000). At 8¢/lb, the digestible portion is worth $128 (0.08 × 1,600). That's about where dairy-quality hay is currently priced in Illinois.

“I need to practice with the numbers a little bit, but I think we're right in the ballpark of where we need to be, plus delivery,” says Guither.

He has his forages tested by Agri-King, Inc., Fulton, IL. Dave Casper, Agri-King's director of nutrition, says the lab routinely tests forage samples for both fiber digestibility (NDFD) and in vitro dry matter digestibility as well as other organic and inorganic components.

He says dry matter digestibility “gives a better reading of how cows will perform.”

Is he right?

“I think the jury is out,” answers Neal Martin, director of the U.S. Dairy Forage Research Center, Madison, WI. “I'm not ready to say that in vitro digestible dry matter is better than in vitro digestible fiber. They give us different things.”

“I think it would be very useful to have both numbers,” comments Mike Hutjens, University of Illinois extension dairy specialist. “That would tell me the digestibility of the least-digestible portion of the carbohydrate — that being the NDF — and also how much is totally available, including the sugars, starches, protein and other organic sources.”

In vitro dry matter digestibility is key because it ties directly to microbial growth, Hutjens adds.

“As bacteria have larger amounts of organic matter to digest, increases in microbial protein and volatile fatty acid (VFA) production can be expected, providing more balanced amino acids and energy to high-producing cows.”

He says the fiber digestibility of forages gets the most attention because it controls intake — an important factor in balancing rations for high-producing cows.

“But I'd like to have them both because it allows me to look at both the cell wall and the total plant,” says Hutjens.

Estimated True Digestibility Of Feed Components
Fraction Of Feed True Digestibility (%)
Cell Contents 93-98
Cell Wall (NDF) 62
Hemicellulose 79
ADF 30
Cellulose 50
Lignin 0
Acid-Insol. Ash 0