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Cool-Season Grass Research Takes Root

Posted Mar. 31, 2008

To carry their herds through the winter months, many ranchers in the southern Great Plains turn to annual rye or wheat systems to provide forage for their animals. These systems, however, require yearly replanting and are costly in both time and money. So, in the mid-1990s, a program was started at the Noble Research Institute to develop a cool-season perennial grass. Now, more than a decade later, the Noble Research Institute is close to achieving this long-sought goal. Perhaps ironically, the candidate grass was found on one of the Noble Research Institute's own farms.

Andy Hopkins, Ph.D., has been working on the forage project since he came to the Noble Research Institute in 1997. Chuck Coffey, pasture and range specialist, pointed Hopkins to a stand of tall fescue growing on the Noble Research Institute's Pasture Demonstration Farm (PDF). The tall fescue, a nonnative grass to southern Oklahoma, had been planted in the early 1970s, and had thrived for almost three decades.

"I speculated that in the 25 years there was natural selection. The weak plants died out and the strong plants survived," Hopkins said. "So over time there was genetic improvement."

Over the next few years, Hopkins went on to collect and test some 3,000 strains of grasses from dozens of species, but the tall fescue from PDF continued to be one of the most promising candidates.

Hopkins discovered that PDF tall fescue possessed a naturally occurring endophyte, a microscopic fungus that lives in the intercellular spaces of the plant, often imparting drought tolerance and persistence to its host. However, the endophyte in PDF could cause "fescue toxicosis" in cattle, a nasty side effect caused by an endophyte-produced toxin that restricts blood flow in cattle. Eventually, the existing endophyte in PDF tall fescue was replaced with another naturally occurring endophyte, a "novel" endophyte, by colleagues at AgResearch, an agricultural research and development company in New Zealand. The novel endophyte offered its host a bevy of positive attributes while not causing fescue toxicosis to the grazing animals.

Since 2002, PDF tall fescue with the novel endophyte has been tested in more than a dozen locations in Oklahoma, Texas, Arkansas, Kentucky and southern Georgia and the results have been outstanding.

"The PDF line performed very well," said Hopkins. "In head-to-head challenges, the PDF line never lost. It also shows better seed yield."

Since 2003, PDF tall fescue with the novel endophyte has undergone extensive safety trials, including lamb trials (2003 to 2006) and beef cattle trials (2005 to present), passing each test convincingly.

But, while PDF tall fescue has succeeded in field trials in comparison to other tall fescues, ultimately it must prove to be more economical than the current annual systems. Jon Biermacher, Ph.D., has been examining the economics of the grass in his role as a Noble Research Institute research economist.

Biermacher's analysis shows that the length of time it takes to establish tall fescue is a problem. While annual wheat and rye forages can be utilized by stocker cattle a few weeks after planting, it can take several months before tall fescue can be grazed. However, Biermacher was quick to point out that once the perennial forage is established it could theoretically grow for many years, providing that it is managed properly.

"Not needing to be established each year is tall fescue's greatest advantage," Biermacher said. "There was a greater upfront cost associated with establishing the tall fescue relative to the annual forage, but this cost can be amortized over the expected life of the forage, providing the producer with substantial savings each year."

Findings show that the economics currently favor the traditional annual system over the tall fescue system.

"The savings in establishment costs of tall fescue are currently not enough to outweigh the benefits that accrue to the annual system from cattle being able to graze the pastures for a greater number of days," Biermacher said. "However, if prices for fuel and establishment equipment continue to grow at their current pace, there will be a point when the relative economics between the two systems will change in favor of the tall fescue system."

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