Implants for growth promotion were introduced for use in livestock in 1957 and are widely used in the cattle feeder and stocker industry. Implants contain natural or synthetic components that result in a physiological response similar to the animal’s natural response.

While there has been consumer concern about growth-promoting hormones, implants have been proven safe and effective. Many foods, including cabbage, soybean oil, peas, eggs and wheat germ, have significantly higher hormone levels than implanted beef.

Beef producers found that implanting cattle more than once results in more efficient gains. Until just recently, implant product labels did not specify how a beef producer could reimplant within a production stage.

Due to unclear labeling regarding reimplantation, the FDA has been working on a process to clarify production periods during which reimplantation is appropriate. Documents published by FDA to clarify labeling were published throughout 2021 and most recently in May 2023.

Dr. Bryan Bernhard, Zoetis beef nutrition, addressed the reimplantation issue, noting that over a year ago, there was an FDA posting regarding ear implants. “Unless otherwise approved and labeled for reimplantation,” said Bernhard, “only one ear implant may be given to an animal during a specific stage of growth.”

This statement led to many questions from customers, veterinarians and nutritionists about the definitions of growth stages and current use of implants across different production phases.

Key clarifications came out in FDA’s May document. “The main points FDA provided clarification on were product labeling, definition of production phases as referenced for Guidance For Industry (GFI) 191, how implants can be used in grow yards, changes in location and/or ownership, no extra-label use for cattle ear implants and the July 1, 2023 deadline,” Bernhard said.

There are currently some cattle ear implants approved for reimplantation within a production phase, and that information is clearly stated on the label. Another group of implants clearly state that the implantation within a production phase is not permitted. “The third is ‘unless a cattle ear implant clearly states on the labeling that they are approved for reimplantation within a production phase, they are not approved,’” said Bernhard.

The FDA defines various production (feeding) phases in GFI 191. “These production phases were not just developed specifically for implants,” said Bernhard. “This document covers all species and is applicable for all pharmaceutical products.”

Rule changes affect cattle implants

Dairy, beef or crossbred animals raised for beef production are eligible for reimplantation if they qualify under a certain production phase. Photo by Sally Colby

The FDA currently recognizes three beef target animal production phases, called variants. Within each variant, there are one or more cattle ear implants approved for use. Variant 1 is beef calves nursing their dams from two months of age until weaning. Variant 2 is growing beef steers and heifers maintained on pasture and receiving most of their diet from grazing. Variant 3 is growing beef steers and heifers fed in confinement for slaughter, referred to as feed yard or feedlot cattle, fed progressively high-energy diets. This phase includes cattle in grow yards.

Bernhard clarified several points, such as starter, grow and backgrounding yards, and feed yards, which are all considered part of one production phase – growing beef steers and heifers fed in confinement for slaughter.

“The key is the grow yard is a subset of confinement regardless of whether they are co-located on the feed yard or housed in a separate facility,” said Bernhard. “So it can be a pen within a broader feedlot or housed in a separate facility. FDA considers ‘grow yard’ to be a subset population of the confinement for slaughter production phase.” A change in ration, such as feeding a progressively higher energy diet, is not a change in production phase.

Producers can administer an implant to an animal within a grow yard if the implant is approved for use in the confinement production phase. But cattle that receive an implant during the grow yard portion may not receive a subsequent implant unless the implants used are approved and labeled for used in a re-implant program within the growing beef steers and heifers grown in confinement for slaughter production phase.

Cattle often change ownership as they move through production phases. “Cattle producers should note that although the FDA does not define a change in production phase as a change in ownership or location,” said Bernhardt, “these changes may be accompanied by a change in production phase.”

Regarding extra-label use if any of these implants are deemed prescription products – can the vet write a prescription for a product that is not in line with labeled instructions? Or can a vet use current products on prescription basis?

Veterinarians must follow all federal and FDA regulations addressing extra-label use of drugs for animals. “The use of growth-promoting cattle ear implants in an extra-label manner including those with a prescription marketing status does not comply with these requirements,” Bernhard said, “and would be an illegal extra-label use that may cause a drug to be adulterated under the FD&C Act and subject to enforcement.”

July 1 was the deadline for pharmaceutical companies to make label changes to implant products. It was the deadline announced in 2021 to allow the industry time to consider current implant programs and to ensure changes were clear.

The two-year period also gave the industry adaptation time to consider current implant programs and make sure producers clearly understood production phases. “Cattle that were implanted or re-implanted prior to July 1 would not be considered adulterated,” said Bernhard. “Per their December 2021 letter, FDA expects that beginning July 1, 2023, producers should re-implant cattle only if the cattle ear implants that are explicitly labeled for use in a reimplantation program for that specific phase.”

The FDA also clarified that implants are only approved for three production phases relative to implants: calf phase, pasture phase and confinement phase.

Bernhard said producers should only re-implant livestock with cattle ear implants explicitly labeled and approved for use in re-implant programs within a specific stage of production. Cattle producers who are unsure about the allowance of any products for reimplantation should contact their product manufacturer representative for clarification.

by Sally Colby