California has adopted the toughest regulations in the country regarding the use of antibiotics in healthy livestock, giving new urgency to scientists and farmers searching for alternatives.
Gov. Jerry Brown signed a bill on Saturday that bars livestock producers, starting in 2018, from feeding antibiotics to animals to prevent illness or promote growth — a move that is expected to have a national impact.
The state is the third-largest source of livestock in the U.S. (PDF), behind Texas and Iowa, according to the U.S. Department of Agriculture. The practice of giving low doses of the drugs to animals when they aren’t sick has raised concerns about spreading antibiotic-resistant infections into the nation’s food supply.
With fast-food restaurants such as McDonald’s and Chipotle responding to consumers’ concerns and pledging to cut antibiotics from most of their chicken, it seems all but inevitable that the practice is on its way out.
But what are the alternatives? For starters, scientists and farmers have been studying the use of prebiotics and probiotics as ways to fend off animal diseases.
Probiotics — beneficial micro-organisms, sometimes called good bacteria — help stabilize animals’ gut bacteria and make them less susceptible to illnesses, explained Irene Hanning, a professor of genome sciences and technology at the University of Tennessee whose research focuses on food safety.
But the problem, she said, is that pre- and probiotics don’t always work. What may work beautifully for one animal won’t be effective for a different kind of animal, and effectiveness can vary even among the same species. “There’s not a one-size-fits-all,” she said.
Scientists say that many organic livestock producers use herbs and plant extracts such as oregano, thyme and eugenol, which have been shown to have antimicrobial properties, especially when used in combination with probiotics. “They swear by things like oregano,” Hanning said.
But others are suspicious of such herbal remedies. “Those are still considered witchcraft” by larger producers, she said.
A successful alternative to antibiotics, Hanning said, would have to be cheap and easy to feed to many animals efficiently — the primary advantages of antibiotics. Probiotics, by contrast, are often put in animals’ water supply. Since the organisms can’t survive there indefinitely, animals that arrive late to the watering hole may not get a very good dose.
Other scientists are tinkering with genetic innovations that boost animals’ immunity, eliminating the need for such medicines.
Animal scientist Mark Cook and his team at the University of Wisconsin at Madison discovered a way to disable an off switch in chickens’ immune systems and have replicated the results in cattle.
“It works in all of them,” said Jordan Sand, an associate scientist with the University of Wisconsin team and the chief technical officer of Ab E Discovery, the spinoff company the team founded to continue its research and take it to market. “This was kind of a serendipity.”
Sand studied cancer research while earning his doctoral degree and knew that the protein interleukin-10 (IL-10) had an important signaling function in the immune system. It tells the immune system when to stop working, he said.
Starting in 2011, the team began by vaccinating egg-laying hens to create antibodies for IL-10 and mixed those eggs into animal feed eaten by 150,000 chickens infected with coccidia, which cause coccidiosis, a common intestinal disease.
By eating the antibody-producing eggs, the animals were able to resist IL-10’s signal for their immune systems to shut off. Very few of the chickens ended up falling sick with coccidiosis, Sand said. “In some cases, we outperformed the drugs,” he said.
When the researchers approached livestock farmers to try their creation and to eliminate antibiotics from their animal feed supply, “they looked at me like I’m nuts,” he said. But now Ab E Discovery is working with two large livestock producers, though he declined to name them because he had not yet cleared it with the companies.
If getting rid of antibiotics can’t be made feasible, that poses a conundrum if animals get sick, Sand said. “Do you just let them die?” he asked. “Instead of worrying about that, we are trying to come up with a reasonable alternative, and we think we’ve got it.”
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