Courtesy of Forest & Kim Starr
A biotech company is conducting a field study of genetically engineered white clover to find ways of improving forage digestibility for livestock.
Forage Genetics, which is best known for alfalfa that’s genetically modified to withstand glyphosate herbicides, began field testing the transgenic clover in Wisconsin this year under a USDA permit that expires in 2020.
The clover contains a gene that’s important for the company’s efforts to engineer “condensed tannins” into alfalfa forage, said Stephen Temple, the company’s biotechnology director, in an email.
Incorporating condensed tannins into forage crops would improve “protein use efficiency” while reducing “nitrogen loss to the environment” and providing “bloat safe grazing options,” Temple said.
The field trial involves growing a “small number” of white clover plants in an “isolation cage” to prevent cross-pollination, he said.
It’s too early to determine whether the gene from the biotech white clover variety will be transferred to alfalfa, as the research and development program may last a decade or longer, Temple said.
“A lot of testing and analytical work will need to be completed successfully before decisions are made on how best to deploy the technology,” he said.
Condensed tannins bind to proteins, preventing them from being digested too quickly and improving the cow’s protein absorption, said John Grabber, a dairy forage researcher with USDA’s Agricultural Research Service.
However, if the cow ingests too many condensed tannins, the binding mechanism will actually impede digestion of protein, he said.
“We don’t want to protect it too much so the protein goes right through the cow and comes out the other end,” Grabber said.
While one study has shown that birdsfoot trefoil — a plant that naturally contains condensed tannins — boosts milk production, other studies haven’t found this correlation, he said.
If protein can be absorbed more efficiently by cows, it would also have environmental benefits, Grabber said. Undigested protein is excreted as urea, which is converted to ammonia.
“We’re hoping tannins might be able to reduce ammonia emissions from farms,” he said.
Genetically engineering alfalfa to contain condensed tannins isn’t necessary for cows to benefit from the tannins, said Bill Freese, science policy analyst with the Center for Food Safety, which is critical of many biotech crops.
Growing alfalfa along with grasses with a high fiber content will prevent bloat, which develops in cattle from eating too much protein, he said.
“There are already solutions to this,” he said. “It shouldn’t be surprising. We don’t eat only one thing, and when cattle eat one thing, it causes problems.”
Forage Genetics’ research into condensed tannins appears aimed at feeding cattle only alfalfa, rather than a mixture of crops that can improve digestion, Freese said.
“It seems like another high-tech way to reduce agricultural diversity,” he said.