Post-Grazing Residual Key to Quality For Grass-Fed Beef

US - Grass-fed beef is catching on with consumers for health and environmental reasons.

20 July 2007

3 minute read

North America

Finishing cattle on pasture requires some pretty astute pasture management. There’s no “wonder-forage” that guarantees cattle will finish well on pasture, warns Jim Gerrish, nationally-recognized grazing consultant in Idaho.

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“At some point, intake from a lot more short bites becomes less than the volume of fewer bit bites, and total energy intake is lowered,”

Jim Gerrish, nationally-recognized grazing consultant in Idaho.

Gerrish, a former University of Missouri beef and forage expert who now operates American GrazingLands Services LLC (http://www.americangrazinglands.com), says to have beef finish USDA high select or better for a “pleasant dining experience” for customers, cattle need to be gaining at least two pounds a day as they near maturity n at a minimum of 60 to 90 days prior to slaughter.

According to standard feed tables, for two pounds of ADG, cattle require 61 percent TDN and 10 percent crude protein. Requirements in the “real world” are somewhat higher; 65 percent TDN and 12 percent CP is “finishing quality forage,” says Gerrish, noting that while it’s easy to keep protein above 12 percent in cool-season pastures, energy is “much more challenging.”

Legumes can provide higher levels of digestible energy than grasses over much of the growing season, and also provide much higher levels of protein. However, when pastures become legume dominant, it’s very easy to have excess non-protein nitrogen (NPN) levels in the rumen and bloodstream that result in reduced animal performance as the energy:protein balance becomes increasingly skewed. Thus, Gerrish recommends that finishing pastures don’t be over 50 percent legume.

What’s more, he notes that some of the “less-desired ‘grassy’ flavor that some pasture-finished beef exhibits” is due to chemical compounds actually found in legumes n not the grass.

However, for long-term sustainability, grass finishers must relay more on legume-fixed nitrogen (N) (and less on fertilizer N). He thinks they should be managing for 30 to 50 percent legume in their pastures.

Of the cool-season grasses, perennial ryegrass is considered the highest energy grass and an “excellent choice” for finishing pasture.

As noted, finishing beef on pasture demands some expert management. Cattle have to balance their daily activities among grazing, ruminating and resting; there’s a limit on how many hours they can spend grazing. The better the condition of the pasture, the fewer hours they must spend grazing.

“Higher energy forage requires less time spent in rumination, so they can spend more time grazing and increase total daily energy intake,” he notes.

What’s more, when pasture conditions are ideal, cattle take fewer bites, because every bite contains more mass. As pasture becomes shorter, they need to take more bites every day. “At some point, intake from a lot more short bites becomes less than the volume of fewer bit bites, and total energy intake is lowered,” Gerrish explains. “Plus they are expending more energy to take those added bites.”