By Fae Holin, Managing Editor, Hay & Forage Grower
Neal Martin and colleagues have two goals in mind for redesigning alfalfa for dairy cattle: reduce the amount of protein degraded in silage and in the rumen, and increase the availability of carbohydrates in plant cells. Martin, director of the U.S. Dairy Forage Research Center (USDFRC) in Madison, WI, spoke at the recent American Forage and Grassland Council meeting in Grand Rapids, MI.
Researchers are looking at how red clover, compared to alfalfa, loses much less protein when ensiled. One redesign technique would be to insert a red clover gene into alfalfa and then add a compound (to mimic the substrate activity present in red clover) to the alfalfa to accomplish protein savings – enough to demonstrate that protein degraded in alfalfa parallels that of red clover, Martin says. A second avenue would be to modify alfalfa so that it will make tannins – natural substances found in some forages such as birdsfoot trefoil. Natural tannins found in birdsfoot trefoil bind to and protect protein during ensiling and while it’s in the cow’s rumen.
To make alfalfa more digestible, researchers are working to reduce the amount of lignin in plants by increasing celluloses and pectins. Lignin keeps plants upright but also lowers digestibility. Proof-of-concept research, in which a gene was inserted into an elite germplasm of alfalfa to modify production of lignin, resulted in more digestible fiber and more milk when fed to dairy cattle. (See the article “Highly Digestible Feed” in the May issue of Hay & Forage Grower or click here.)
A new alfalfa with reduced lignin and reduced protein degradation could allow producers to feed lower-protein diets, allow for the digestion of complex carbohydrates and reduce the number of cuttings per season. For more information on reduced lignins, watch for the August issue of Hay & Forage Grower.
“We are fortunate to be working within a model public-private research partnership called the Consortium for Alfalfa Improvement,” Martin says of the effort to provide dairy cows with the best alfalfa possible. Besides the USDFRC, the consortium consists of the Noble Foundation, Forage Genetics International and the USDA-ARS Plant Science Research Unit in St. Paul, MN.
The USDFRC is also working on new developments in grasses. Grass studies are looking at the agronomic potential of meadow fescue and the response to nitrogen rate and grazing management by Bronc orchardgrass, Barolex soft-leaf tall fescue, and Azov, Bartura and Hidden Valley meadow fescues.
“We have changed the focus of grass breeding from hay harvesting to grazing,” Martin says. “New varieties with unique traits are being developed to simplify and enhance grazing operations – and there’s growing interest and a growing market for these types of varieties.” Look for more information in coming issues of Hay & Forage Grower and eHay Weekly. hayandforage.com/ehayarchive/0714-researchers-stive-improve-forages