Grass-fed vs. Grain-fed

There’s a difference.

by Shelby Mettlen, assistant editor

MANHATTAN, Kan. (June 15, 2016) — University of Missouri professor Gavin Conant addressed listeners June 15 at the annual Beef Improvement Federation symposium in Manhattan, Kan., explaining that his research on the metabolic network indicates there is a difference in performance and efficiency of grass-fed vs. concentrate-fed animals.

“What we’re really saying here is when you switch the diet, when you change the diet from what it has been to something new, you introduce diversity,” Gavin Conant explained. “When you change the diet, different animals find different solutions. Sometimes they find bad solutions.”

Not surprising, Conant admitted, but when he and his research team looked at eight grain-fed ruminants and eight grass-fed ruminants, he didn’t expect the results he found.

Conant and his team studied 16 sheep, all started on a forage-based diet. After a few months, half the animals were switched from a forage-based diet to a concentrate-based diet. What he and his team found was that the two diets caused the animals to carry the weight of their metabolic networks on opposite sides of the rumen: For the grain-fed animals, it was the left side, and for concentrate-fed animals, it was the right.

“What that’s saying,” Conant said, “is they’re eating things that are pretty different from the things that the host genome can deal with. So it’s a bigger problem to feed those animals grasses, to configure those odd metabolites into something the host can absorb, than it is for animals consuming a concentrated, grain-based diet.”

Across the board, Conant found that the eight animals with forage networks were fairly similar, but among the eight concentrate-fed animals, Conant found eight different networks.

Four of the eight concentrate-fed animals had metabolic networks similar to the forage-fed animals, and of those four, three had low feed efficiency. The low-feed-efficiency animals were similar to the forage-fed animals because their rumen ecosystems essentially collapsed, he said.

Conant said he is hypothesizing that having an inefficient rumen can be caused by this type of collapse because “there’s not enough diversity there to process all the nutrients coming in.”

A healthy gut contains many different species of enzymes and bacteria, which helps its efficiency in processing nutrients.

“What we’re really saying here is when you switch the diet, when you change the diet from what it has been to something new, you introduce diversity,” he explained. “When you change the diet, different animals find different solutions. Sometimes they find bad solutions.”

When an animal is born, the entire rumen is a clean slate that the animal has to assemble for itself, Conant said. As producers and cattle feeders, we’re operating on top of both the metabolic systems in the rumen, trying to make the animals do things we want them to do, like grow more efficiently.

“If we’re fighting evolution, we’re going to lose every time, because operating on time scales of years and sample sizes of dozens, whereas microbes are operating on time scales of minutes and sample sizes of billions. So if we try to fight that, we’re going to lose every time,” Conant said. “We have to learn how to align their edges to ours and to correspond with our roles for the animal.”

Editor’s Note:This summary was written under contract or by staff of Angus Media. Through an agreement with the Beef Improvement Federation, we are encouraging reprinting of the articles to those who will adhere to the reprint guidelines available on this site. Please review those guidelines or contact Shauna Rose Hermel, editor, at 816-383-5270. PowerPoints are posted with permission of the presenter and may not be reproduced in whole or in part without the express permission of the presenter.

Angus Media's coverage of the event is made possible through collaboration with BIF and sponsorship of LiveAuctions.tv. For questions about this site, or to notify us of broken links, click here. Look for additional coverage in the Angus Journal, the Angus Beef Bulletin, the Angus Journal Daily, the Angus Beef Bulletin EXTRA and Angus TV.