Protein confusion in feed wheat

Feed expert says grain companies and feed mills have different ways of calculating protein. | File photo

Rex Newkirk is constantly fielding calls from farmers and feed companies wondering why their wheat is being assigned a higher protein level at the feed lab than it is at the grain elevator.

The chair in feed processing technology at the University of Saskatchewan says the two sectors have different ways of calculating protein with the upshot being that feed mill values are 9.6 percent higher than grain company values.

“So if I buy a 13 percent wheat at the elevator, it’s actually 14.3 percent protein as far as a feed value goes and the (nutrient composition) tables I should be looking up in my books,” he said.

Crude protein levels are determined by measuring the nitrogen content in the grain and multiplying it by a conversion factor.

The feed industry developed the formula about a century ago.

“That was initially done with meat and bone meal because that’s what was most variable and that’s what they were struggling with in the formulation,” he said.

The chemists came up with a multiplication factor of 6.25, which was later applied to other feed ingredients such as wheat.

The reality is that each ingredient should have a different multiplier, and in fact, each cereal crop should have a different multiplier. However, that’s the way the feed industry has evolved.

The grain milling industry later tackled the protein issue and determined that the multiplier for wheat should actually be 5.7.

Most farmers don’t know that there is a difference and often rely on the lower value assigned by the grain elevator when delivering to the feed mill.

“The higher the protein the more valuable it is, and we’re underestimating it,” Newkirk said.

“Now, you could argue that we’re not actually using the right value in the first place, but it doesn’t matter. That’s the system we use.”

Mary Lou Swift, director of nutrition at Hi-Pro Feeds, said feed mills don’t buy based on protein. The price is determined by factors such as moisture content and bushel weight.

However, they do test for protein because levels can vary by seven to eight percentage points in wheat, which is a wide range.

“That’s why we have spent so much on technology to measure it,” she said.

Protein levels at Hi-Pro are calculated using the 6.25 multiplication factor, which means the levels are almost always higher than at the grain elevator.

“So we just don’t run into a conflict with this,” said Swift.

Tim Armstrong, general manager of New Life Mills for Saskatchewan, said most feed mills have quality assurance and quality control systems in place and are testing ingredients all the time.

“You’re basically doing lab analysis for all your incoming ingredients,” he said.

“We would, and I would say probably the majority of people would.”

Newkirk said feed mills don’t formulate based on protein anymore. Instead, they are more interested in essential amino acids such as lysine.

“But the amino acid values we assign to our feed is based on the protein content,” he said.

Nutrient composition tables are based on protein content, and generally speaking, the higher the protein level the higher the lysine level, which is what the feed mills are after.

However, Swift said that relationship breaks down once you reach about 14 percent protein.

“I don’t gain anything by having a 15 (percent wheat) over a 14,” she said. “That’s why we don’t pay you more for higher protein.”

Newkirk said farmers aren’t the only ones confused by the different ways to calculate protein levels.

Some feed mills don’t understand the difference and are incorrectly using the grain elevator’s lower protein value to pick which nutrient composition table to use.

That means they are assigning the wrong amino acid level to the feed wheat and consequently over-formulating their rations.

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