In the negative drum roll about animal agriculture’s role in antibiotic resistance, the Washington State Dairy Federation’s commitment to promoting the judicious use of antibiotics offers a bright note of forward progress.
In an antibiotic stewardship project begun in 1999, the federation joined forces with the Pierce County Antibiotic Resistance Taskforce to evaluate the use of antibiotics on dairy farms in Washington state.
Subsequent research has followed on the heels of that initial multi-year project and is ongoing. Partners in these projects include the dairy farmers, the state’s dairy federation, Centers for Disease Control and Prevention, Washington State University, Cornell University, USDA, and the Washington State Department of Agriculture.
In the initial project, two surveys were sent to dairy farmers to evaluate antibiotic use and farm-management practices. Participation was high, with 381, or 65 percent, of the dairy farmers in the state agreeing to participate in the first survey, which went out in 2003.
For the dairy farmers, the underlying goal was to preserve the power of antibiotics. The fear of losing that power through antibiotic resistance led them to take a close look at various practices on their farms.
But they also had, and continue to have, another goal in mind as well. They want consumers to know that they’re taking the public’s concerns about antibiotic resistance seriously and are taking steps to prevent it from occurring on their farms.
Nationwide, one to two dairy farms per week get warning letters from FDA about animal drug abuse. Most involve excessive use of antibiotics.
In a mail survey sent out to a nationally representative sample of consumers, antibiotics rated third of eight concerns cited, with pesticides and artificial growth hormones at the top of the list.
In the first survey the dairy farmers participated in, more than one-third of the respondents said they believed that antibiotics that worked well in the past were no longer as effective for treating the same conditions.
Most of the respondents agreed that antibiotics become less effective the more they’re used and that the use of antibiotics in food-producing animals could impact human health.
There was also general agreement that judicious use of antibiotics is in the best interest of both human and animal health and welfare.
The findings of the surveys led to recommendations about antibiotic use, a tool kit containing three self-assessment guides, and a reference manual on disease management and antibiotic use on dairy farms.
The manual, which was sent to every registered dairy producer in Washington state, was designed to encourage producers to work with their veterinarians to diagnose diseases correctly and to select the right treatment. Written in bold letters was this message: “Antibiotics use cannot replace sound management practices.”
The tool kit’s introduction took a similar tack: “Anytime an antibiotic is used in humans or animals, resistance to the antibiotic can develop. Resistant bacteria can cause infections that are difficult to treat and often require stronger and more expensive drugs.”
One of the concerns about antibiotics in animal agriculture is the use of sub-therapeutic levels of antibiotics ( lower amounts of antibiotics than would be needed to treat an animal that is ill) to promote growth and prevent disease — and the role that practice plays in building resistance to antibiotics in farm animals and possibly humans.
That’s in contrast to using an antibiotic to treat a sick animal — a practice generally deemed to be acceptable by animal- and human-health experts.
An example of sub-therapeutic use of antibiotics is the practice of feeding calves milk replacers that contain low levels of antibiotics as a safeguard against some calf diseases. However, some dairy farmers use non-medicated milk replacers or don’t use milk replacers at all, instead feeding whole milk until the calves are weaned.
According to the project’s survey results, less than one-third of the dairies in Washington state participating in the project were using medicated milk replacers.
The survey also revealed that the practice of feeding calves colostrum (often referred to a cow’s “first milk” after calving) to pass along immunity from the mother was widespread and that farmers would benefit from additional testing to ensure that adequate immunity was passed from mother to calf.
After the project’s “educational intervention,” 51 percent of the producers who originally reported using medicated milk replacer discontinued the practice, although 12 percent of the producers began using medicated milk replacer between the 2003 and 2005 surveys, according to a 2006 assessment of the project.
The assessment also revealed other areas where additional work was needed: increasing veterinary involvement in antibiotic-use decisions, implementing treatment protocols, enhancing biosecurity, and ensuring that optimal immunity was passed from the cow to the calf.
Veterinarian Dale Moore, director of Veterinary Medicine Extension at Washington State University, said that the group working on the project concluded that the project’s greatest accomplishment was improving dairy farmers’ awareness about the judicious use of antibiotics, which she describes as “the first step to making change. ”
A subsequent USDA-funded research project begun in 2007 on a large dairy farm by a team of WSU veterinary scientists, including Moore, found that raising calves without using milk replacer containing sub-therapeutic levels of antibiotics was actually healthier for the calves and more profitable for the farmers.
“Because of concerns that antimicrobial use in food animal production has the potential to increase antimicrobial resistance in human pathogens, alternative strategies to widespread antimicrobial use are needed,” says the first sentence of the introduction in the published report about the project.
Antimicrobials are substances that kill or inhibit the growth of microorganisms such as bacteria, fungi, or protozoans. The terms “antibiotics” and “antimicrobials” are often interchanged.
According to the World Health Organization, widespread use of antimicrobials for disease control and growth promotion in animals has been paralleled by an increase in resistance in bacteria — such as Salmonella and Campylobacter — that can spread from animals, often through food, to cause infections in humans.
Here in the United States, there is zero tolerance for antibiotics in any milk going to a processor. Each batch is tested before going into the commercial milk supply. Antibiotic residues in meat are also prohibited, although they are sometimes detected and reported in the news.
Last summer, for example, saw two separate massive recalls of hundreds of thousands of pounds of ground beef linked to outbreaks of two different strains of antibiotic-resistant Salmonella that sickened people in more than half a dozen states.
On the food-safety front, scientists say that keeping antibiotics out of the food supply is critically important because antibiotic resistance on the part of foodborne pathogens, such as E. coli, Listeria, or Salmonella, would be a blow to the effectiveness of antibiotics that are typically used to treat foodborne illnesses.
With that in mind, the USDA recently awarded a $2 million grant to Kansas State University epidemiologist H. Morgan Grant to work on a project focused on improving food safety by finding ways to manage antibiotic resistance in beef and dairy cattle systems in the United States and Canada.
Earlier this year, USDA scientists and cooperators — using an advanced genetic screening technique — detected, for the first time, more than 700 genes that give Salmonella, E. coli and Listeria, among others, the ability to resist antibiotics and other antimicrobial compounds.
Responding to increasing concerns about antibiotic resistance, the U.S.Food and Drug Administration on June 28 released a set of draft guidelines aimed at the judicious use of antibiotics in animal agriculture.
“Using medically important antimicrobial drugs as judiciously as possible is key to minimizing resistance development and preserving the effectiveness of these drugs as therapies for humans and animals,” said Bernadette Dunham, director of the FDA’s Center for Veterinary Medicine, in a press release about the guidelines.
When asked about the Washington State Dairy Federation’s work promoting antibiotic stewardship, Jay Gordon, a dairy farmer who serves as director of the federation, said that for the dairy industry, it’s a matter of survival.
He pointed out that animal agriculture isn’t likely to get the higher-powered, new-generation antibiotics developed for human health. For that reason, he said, it’s important for dairy farmers to take steps to make sure the antibiotics they currently use to treat sick animals continue to work for them.
Jesse Robbins, program manager for the federation, said that WSU researchers recently received a USDA grant that will largely continue where the original project left off.
One of the goals of the new project is to gain a better understanding of the organizational structure of large dairy farms so that information about the prudent use of antibiotics can be shared with employees up and down the chain of command.
That’s important, said Robbins, because while the owners of large dairy farms might understand the need for the judicious use of antibiotics, it’s often the employees who make decisions about how the cows should be fed and treated. For that reason, they need to be in the loop, as do veterinarians, when antibiotics are used.
With collaborators at Cornell University, project researchers will also evaluate calf housing and management strategies to stop the transmission of resistant bacteria along rows of very young calves in hutches (individual housing units for calves).
The researchers will also do molecular work to determine whether the specific antibiotic resistance genes in the cattle bacteria are the same ones that are found in human resistant bacterial infections, such as Salmonella.
As part of the initial antibiotics stewardship project, eight dairy farmers agreed to work with their veterinarians to create, implement, and evaluate individualized plans aimed at the appropriate use and infection-control practices on a dairy farm. That information was then shared with the other dairy farmers.
One of the farmers, Larry Stap, co-owner of Twin Brook Creamery in northwest Washington, said that antibiotic use varies from farm to farm and that overall it’s far less prevalent than it was 20 years ago.
“Back then, if a cow looked cross-eyed, you gave it a shot,” he said.
Stap said that even before he became involved in the project, his farm relied on good management practices — not antibiotics — to keep its cows healthy.
“Prevention is far more important,” he said, referring to cleanliness, good nutrition, and biosecurity.
He doesn’t believe that a farmer should use antibiotics to compensate for poor management practices, such as overcrowded conditions or pushing the cows to get “massive amounts of production.”
“Their health is so important to us,” he said.
Case Vander Meulen, owner of Coulee Flats Dairy in Eastern Washington, which milks 4,200 cows, said that large dairy farms, not just small- and medium-scale dairies, can also be good antibiotic stewards.
Like Stap, Vander Meulen said that making sure the cows have good housing, a clean environment, supportive care when necessary, and good feed are the basis for healthy cows.
However, both agree that there’s a place for antibiotics on a dairy farm and that a dairy couldn’t operate if there was a blanket ban against antibiotics. There are times when cows need to be treated with antibiotics, just as there are times when humans need to be treated with them.
Both dairymen are quick to say that in all of this talk about antibiotic resistance, the misuse of antibiotics in human health needs to be factored into the equation.
“Animal agriculture is more than willing to do its part to not misuse antibiotics, but we can only hope the (human) medical field will do its part,” said Stap.
“Commercial livestock operators are way, way more conservative in using antibiotics than doctors,” said Vander Meulen. “Almost any time you go to the doctor, you walk out with a prescription for antibiotics. It’s just too easy to get antibiotics.”
Looking ahead, Vander Meulen predicts that livestock producers will see more and more limits on the antibiotics they can us.
“I don’t feel very good about it when people who don’t understand the science of this base their opinions on what livestock producers should do,” he said.
Asked about what message he’d like to get out to the public, Vander Meulen said: “Please educate yourself before you cast judgment.”
In a fact sheet about antibiotic resistance, CDC cites concerns about the medical abuse of antibiotics in humans. In the case of pediatric care, for example, a study showed that doctors prescribe antibiotics 62 percent of the time if they perceive parents expect them to and 7 percent of the time if they feel parents do not expect them to.
In addition, antibiotics were prescribed in 68 percent of acute respiratory-tract visits. Of those, 80 percent were unnecessary, according to CDC guidelines.
Also, according to CDC, $1.1 billion is spent annually on unnecessary adult upper-respiratory infection antibiotic prescriptions.
Human health experts also point to other problems that can lead to antibiotic resistance. Sometimes people don’t finish the full course of antibiotics prescribed for them, which happens when a patient starts feeling better and decides to stop taking the antibiotic. In other cases, people “self-prescribe” and use antibiotics friends or relatives might have on hand.
More research on antibiotic resistance on Washington state dairy farms is in the works. The Washington Dairy Products Commission has funded a research project that will investigate using bacteriophages (viruses that infect bacteria) instead of antibiotics to control several dairy cattle diseases. (See tomorrow’s Food Safety News site for more information about bacteriophages.)
“As you can see, we have taken a very progressive stance on antibiotic stewardship and will continue to do so,” said Washington State Dairy Federation’s program manager Robbins.
Washington state currently has about 400 conventional dairies and about 42 certified organic dairies. Organic dairies are not allowed to treat their cows with antibiotics. If they do, they have to remove the cow from the herd.
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