Southwestern cattlemen who run stocker cattle from fall through spring rely almost exclusively on wheat or ryegrass to provide acceptable daily gains.
“They need a perennial cool-season forage grass,” said Andy Hopkins, a forage grass breeder with the Noble Foundation in Ardmore, Okla.
Hopkins says current options, which include wheat, ryegrass or hay, are expensive and labor intensive.
“Stocker cattle provide an important contribution to our farm economy,” Hopkins said. “Operators can buy calves relatively cheaply in late summer and can make a fairly good profit with an inexpensive forage.” But they need a more affordable forage system.
He said the problem with cool-season forage has been persistence. Producers can't keep stands viable under the harsh conditions of the Southwest. “Heat and drought produce more stress than our cool-season grasses can endure,” he said. “So we're looking for perennials that can tolerate heat and drought stress and still provide good nutrition for cattle. The right cool-season forage would benefit cow/calf producers as well.
Hopkins says he and colleagues “are looking at a broad range of germplasm, including tall fescues, hardinggrass, western wheatgrass, Texas bluegrass, Russian wildrye and tall wheatgrass. We're probably looking at 10 to 15 different species. We'll narrow the field significantly in a few years.”
Given no choice
Hopkins and other team members establish forage selections and then graze them heavily. “We overgraze to make certain we stress the stand,” he said. “We don't give the animals a choice; they have to eat what's there.
“Also, within a two-year period we usually encounter heat and drought stress, so we evaluate how well certain selections withstand those conditions. Irrigating forages usually is not feasible, so we are trying to identify strains with the best recovery and test them further.”
In addition to evaluating grazing stress tolerance, researchers also determine forage quality.
Hopkins says testing includes numerous locations. “We also test for persistence and seed production. After we identify superior germplasm, we'll spend several years testing. It takes a lot of time because we have to make certain that we develop something that's better than anything farmers already have.”
He says the final step before releasing a new variety is to evaluate animal performance. “That's the ultimate test. We have to see if the forage produces the average weight gains necessary for profit.”
Hopkins says the effort is “about half way to a cultivar.”
Much of the work has been old-fashioned applied breeding. “Breeders did little with forages before 1930,” he said. “The Dustbowl was the catalyst to start.
“Our team works together on projects and we take advantage of genetic engineering where appropriate.”
Lignin, he says, is one area where genetic engineering could benefit forage breeding. “Lignin, an essential part of the plant's structure, interferes with digestion. Lignin also provides some disease and insect resistance. So, we're looking at changing the amount of lignin in the plant or changing how it acts.”
They're also looking at endophytes, a fungus inside the plant that helps with stress tolerance but can cause health problems for animals that eat it. “We're trying to take out the bad endophytes and keep the good ones,” he said. “This is an indirect approach to drought stress tolerance.”
He said molecular markers may help breeders identify potential cultivars and improve research efficiency.
Hopkins said forage breeding is complex work. “We're looking at some complex scientific problems that are not easily solved,” he said. “We're using a lot of technology to develop a better product for farmers.”
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