The Veterinary Feed Directive (VFD), a part of the Animal Drug Availability Act of 1996 (ADAA), has been amended by the Food and Drug Administration (FDA) in order to better regulate how antibiotics deemed medically important for human use are utilized in livestock.

Primary changes to the VFD exclude the use of these medically important drugs – some of which are currently used in commercially available medicated feed – for growth promotion or feed efficiency, and require veterinary oversight of these medications. Full implementation of the amended VFD rules will take place by Jan. 1, 2017.

“Dairy farmers should be aware that some of the commercially available medicated feed products will soon have oversight responsibility shifted to their veterinarians,” Robert Lynch, DVM, with Cornell University’s Pro-Dairy program, said. “The medicated feed additives [MFAs] containing antibiotics classified as medically important to human medicine will only be permitted to be used to treat, control and prevent disease, provided the product has been labeled for such use. Sponsors of these products will be updating their labels to match the new guidelines. These products will no longer be approved to be fed solely for growth or feed efficiency purposes.”

The VFD relies on the establishment of veterinarian-client-patient relationships (VCPR). The legal ability to prescribe treatment utilizing these important medications hinges upon continual, ongoing oversight a treating veterinarian has in regard to the herd’s health. A treating veterinarian must establish his or her relationship to the livestock, and follow strict protocols when prescribing these drugs, including dosage, frequency, method of administration, animals to be treated, reason for treatment and the specific duration of treatment.

The basis of these final rule changes is the FDA’s acknowledgment that medically important drugs “labeled for continuous or undefined durations of use is not consistent with judicious use principles, as outlined in previously released guidance documents.”

Lynch was the managing veterinarian at Zoetis Dairy Technical Service when he addressed the principles of antibiotic stewardship during the Cornell Calf and Heifer Congress 2015. Lynch explained that antimicrobial resistance occurs because the drug serves as a selection mechanism. Bacteria that are not susceptible to the medication survive treatment and can then transfer their genetic material to other bacteria, ultimately creating a resistant population.

That population can potentially be transferred from animal to human, decreasing the effectiveness of our medically important antibiotics. Some proposed pathways of animal-human transmission include manure containing resistant bacteria moving into soils and water, the use of animal byproducts in domestic or livestock animal feed, or via antibiotic residues in meat and milk. The pathways could potentially be multiple and varied.

Stewardship

Using antibiotics in livestock production responsibly requires several steps. Antibiotic stewardship demands that the use of these medications is necessary, defendable, organized and leaves no residues, Lynch said. Preventing disease through stress reduction, healthy environments, vaccines, optimal nutrition and other management practices is a first defense.

Using antibiotics to treat disease issues, or to control existing threats and prevent disease spread, is prudent. “Metaphylaxis” is the medicating of entire at-risk groups in advance of a challenge, and has been shown to be effective for bovine respiratory disease prevention, for example. Preventative drug use, when warranted and prescribed by a veterinarian, is a responsible use.

Tools to use antibiotics responsibly on the farm include written plans and treatment protocols. Employee compliance with these is crucial. No protocol is effective if it isn’t followed. Research by Washington State University Extension has shown that about 50 percent of the Northwest and Northeast dairies that have written protocols for mastitis, metritis and lameness do not follow them. Pneumonia protocols faired better, with 89 percent of the dairies with plans following those directions.

Producer programs

The Wisconsin Veterinary Medical Association has introduced Food Armor certification to prevent antibiotic residues. It is a hazard analysis and critical control points (HACCP) on-farm program to ensure the safety of milk and meat. Dairy farms wishing to become certified must work with a program veterinarian, evaluate their drug use, put protocols in place for the use of the drugs, develop standard operating procedures (SOPs) that are achievable for the farm and keep records. Other programs in which dairy producers can enroll, such as the New York State Cattle Health Assurance Program (NYSCHAP), share the goals of increasing herd health and productivity while ensuring food safety and environmental stewardship.

Antibiotic stewardship on dairy farms requires prudent, judicious, responsible and appropriate use of medically important drugs. Preventing and treating animal health concerns should not be a route to increase human disease concerns, due to the overuse of antibiotics and the development of resistant microbes. Maintaining herd health requires prevention, veterinarian oversight, risk assessment, treatment protocols, documentation and record keeping. It requires protection from antibiotic residues in meat and milk, as well as in waste products from the farm. The changes to the VFD, which limit the use of MFAs, are supported by the industry, Lynch emphasized.

“MFAs will remain as important health management tools in animal agriculture. We are simply taking additional steps to further promote good antibiotic stewardship,” Lynch said. “Producers can ask their veterinarian and nutritionist if anything they are currently feeding is affected and review with these advisers how to use MFAs, if needed, going forward.”  PD

Tamara Scully, a freelance writer based in northwestern New Jersey, specializes in agricultural and food system topics.