In Feed, Researcher Discovers
Not All Proteins Are The Same

By David Bowser

DEMING, N.M. — Dr. Mark Peterson is interested in finding ways to trick an animal's system into doing a better job.

The New Mexico State University professor has been studying bypass protein in cattle for about 10 years.

"We're encouraged with the results that we've gotten so far," he says.

The initial studies were done to help reduce costs of range supplementation while still producing the same results.

"The overall goal of our research program is to discover a nutritional management scheme that improves productivity at a lower cost," Peterson says. "We've been struggling with this idea since the early 1980s when we had a pretty severe financial crisis in agriculture. The people we were working with at that time wanted to produce the same with less money. That has been the goal of our research program."

While Peterson did much of his research at Montana State University, he drew on the work of Dr. Joe Wallace at New Mexico State.

"Dr. Wallace has done much of the work on protein supplementation as we know it today," Peterson says. "Many of the formulas you buy from commercial feed companies use the ideas that Joe had developed in research programs. He used a protein supplement to meet the requirements of microbes in the rumen. When we do this, it improves the digestibility of the feed. It improves intake. The net effect is it increases both energy and protein intake, so we find improved animal performance."

But Peterson took another route to improve animal performance.

"Bypass protein is different than the type of protein that Joe was working with," he explains. "This is protein that's digestible in the small intestines but is not digestible in the rumen. That means we don't use it to feed the microbes."

Bypass protein usually consists of byproduct feeds that have been heated, such as fish meal, feather meal or corn gluten meal, which comes from corn grain after the oil has been removed from it. There are also treated soybean products, brewer's grains and distiller's grains.

"These are all high in bypass proteins," Peterson says. "They allow for increasing the protein quantity and quality that reaches the small intestines. Normally, we're limited to just what the microbes can make, but when we use these types of protein sources we can make significant change in the type of protein the animal has available."

Animals consume protein in two forms in their diet. One is degradable protein, which is flushed out of the rumen and into the small intestines, along with the energy component in the forage and the rumen microbes.

"Normally, that's what an animal uses for its protein source," Peterson says.

However, bypass proteins are not used by the microbes. They flow through the rumen intact and go to the small intestines along with the microbial protein to add more protein for absorption.

One thing bypass protein does is stimulate the hormone insulin, Peterson says. Insulin opens up the cells so nutrients can go into them. It also provides the building blocks for the cow's blood sugar or glucose.

"Cows really have very few sources to make glucose," he says, "so this is a very important nutrient in this bypass protein."

Bypass protein also discourages weight loss.

"It actually changes the signal to the tissues so the animal won't lose as much weight," he says.

And it encourages the retention of protein tissue such as the protein that is in the liver.

"If you can keep that liver working well, the whole animal's metabolism works better," Peterson explains.

It also improves energy metabolism. It's more efficient, and the less energy that is wasted as heat, the more energy that is available for production purposes.

"As we look at formulating supplements of bypass protein, one of the requirements is that we have crude protein that meets the requirements of the microbes in the rumen first," he says. "That would mean that we want to use natural protein sources like cottonseed meal, soybean meal, sunflower meal, even a small amount of urea to meet that need."

For the bypass protein he uses mixtures of protein sources such as fish meal with feather meal, fish meal with corn gluten meal, or some sort of combination. The purpose of a combination is to get the best complement of amino acids.

"None of those protein sources are perfect, so we add two of them and we make it better," he says.

He recommends a ratio of rumen degradable and bypass protein of half and half. Its use is most effective with young cattle that lose weight.

"If you're in a situation where you expect cattle to lose weight, these protein sources are most effective," Peterson says.

Some research, however, indicates that with cows in good condition and milking, bypass protein may cause them to produce too much milk, and may actually cause a negative effect on reproduction.

Peterson says his research indicates that bypass protein costs a little, more but additional performance more than pays for it.

"I think we can make the generalization that we want to use bypass protein when weight loss is expected," he says. "In every case in all these studies, we showed that that little bit of bypass protein reduced weight loss."