The US Food and Drug Administration (FDA) recently rolled out new voluntary guidelines for antimicrobial usage in poultry and livestock – not just how the medications are categorised and prescribed, but also how, when and why they should be administered in the field.

The two documents, officially known as Guidance for Industry (or GFI) No. 213 and a proposed Veterinary Feed Directive (VFD) regulation, aim to help producers, veterinarians and pharmaceutical companies use antimicrobials in ways that, according to FDA, address public health concerns while maintaining the health, performance and welfare of poultry and livestock.

Although GFI 213 is written primarily for drug 'sponsors' – those companies that own the right to market the drug – the content of the document will inevitably affect everyday management practices for veterinarians and producers. The updated VFD regulation is intended to simplify and streamline the existing process for veterinarians to authorise the use of certain animal drugs in feed.

What Does the New Guidance Mean for You?

Lloyd Keck, DVM

Poultry Health Today asked Lloyd Keck, DVM, a senior technical service veterinarian at Zoetis Inc, to break down the nuts and bolts of GFI 213, VFDs and why they matter to commercial poultry producers.

What does FDA hope to achieve with this guidance?

LK: More than anything, FDA wants the poultry and livestock industry to think twice – and consult a veterinarian – before orally administering any antimicrobial drugs that have been deemed “medically important” to humans.

In other words, any drugs that are considered important for treating infections in people — penicillins, tetracyclines, fluroquinolones and macrolides, to name a few – should be used sparingly in animal feed and water and only to target specific diseases or organisms.

Why are the guidelines specific to feed medications?

LK: The guidelines are specific to in-feed antibiotics because they are well suited to mass administration – and therefore of greater concern than, say, injectable drugs, which have to be given to one animal at a time and typically only for therapeutic purposes. It’s also a way of focusing on antibiotics that have production claims, virtually all of which are administered through feed.

What is the difference between an antibiotic and antimicrobial?

LK: Antibiotics are substances produced by a microorganism that kill or prevent the growth of another microorganism. Antibiotics are antimicrobials, but antimicrobials also may be synthetic compounds.

How does FDA determine which antibiotics are medically important to humans?

LK: Medically important antibiotics fall into three different categories: important, highly important and critically important.

An antimicrobial is considered important if there is cross-resistance within its drug class, or linked resistance with other drug classes. These types of resistance occur when disease-causing bacteria become tolerant to one drug through exposure to another similar drug.

An antibiotic is considered highly important if it’s used to treat enteric pathogens that cause food-borne illness, or if there are no or few other alternatives for treatment of human disease. Finally, if it satisfies both of these criteria, it’s considered critically important.

Are medically important antimicrobials still approved for use in food animals?

LK: Yes. Under the new guidelines, producers are advised to obtain a Veterinary Feed Directive (VFD) order before using any medically important antibiotics in poultry.

Then, these antimicrobials should be used only to prevent, control or treat a disease indicated on the product label. Although the agency acknowledges that improved growth and feed efficiency might be secondary benefits of healthier animals, using medically important antimicrobials only for production benefits is not considered a judicious use of such drugs under the new guidelines.

What is a Veterinary Feed Directive and how do you get one?

LK: Basically, the VFD is a written statement that lets producers obtain and use certain drugs in poultry or livestock feed according to label instructions. VFD drugs must be used under veterinary supervision and in compliance with their FDA-approved labels.

The current VFD process is pretty straightforward. Typically, a licensed veterinarian with an established veterinarian-client-patient relationship assesses the situation and determines whether it’s necessary to use a VFD drug. If so, the veterinarian issues a signed VFD order. Under the new guidelines, FDA has relaxed some administrative procedures, as numerous drugs that were OTC now fall under the VFD umbrella. FDA is now reviewing procedures for obtaining a VFD and is expected to announce changes to the process sometime this year. For more information on the new procedures, visit FDA.gov and search for Veterinary Feed Directive.

Are VFDs needed for all feed medications?

LK: No, VFDs are only needed to obtain medically important drugs.

Which antibiotics are not covered by the guidance?

LK: There are two notable exceptions to the new FDA guidelines that poultry producers and veterinarians need to understand.

First, the new FDA recommendations don’t apply to synthetic anticoccidials or ionophores used in feed to prevent or control coccidiosis. These compounds are not considered medically important to humans and are used almost exclusively in poultry and livestock.

The other exception is any group of feed antibiotics not considered medically important to humans. In poultry, this would include antibiotics in the bacitracin and bambermycins families. Approved combinations of anticoccidials, ionophores, bacitracins and other non-medically important drugs also may be used without a VFD.

That means poultry products like BMD (bacitracin methylene disalicylate) can still be used without a VFD to prevent or control necrotic enteritis, another widespread and potentially deadly gut disease, although veterinary involvement with any antibiotic is still recommended. When used at 50 grams per ton of feed – coincidentally the same level routinely used to prevent necrotic enteritis – BMD can still be used for “increased rate of weight gain and improved feed efficiency.”

Flavomycin 4 (bambermycins) is another poultry feed medication that can be used without a VFD to aid feed conversion and growth rate.

Previously approved combinations of anticoccidials, ionophores, bacitracins and other non-medically important drugs also may be used without a VFD according to label directions.

Will some antibiotics still be available to promote growth and improve feed efficiency?

LK: Yes, “increased rate of weight gain” and “improved feed efficiency” will still be approved claims for some non-medically important feed antibiotics. However, it should be noted that these antibiotics don’t actively promote growth. Increased weight gain and feed efficiency result from the antibiotic’s ability to preserve the integrity of the gut wall, helping to ensure the absorption of nutrients from feed.

Why did FDA adopt a voluntary approach?

LK: FDA adopted a voluntary approach to address public concerns about on-farm antibiotic use, while acknowledging the important role that antibiotics have historically played in keeping animals healthy. It also takes into account the impact of the proposed changes on the animal pharmaceutical industry, producers, the feed industry and veterinarians, giving everyone a chance to get on board with the agency’s new direction. Over the next three years, the agency plans to monitor industry progress and decide if more action is required.

If the guidelines are voluntary, what incentives are there to comply?

LK: In three years, FDA plans to evaluate the rate of adoption of its proposed changes. If it thinks the process needs a boost, it may consider stricter enforcement.