4 December 2024

3 minute read

By: Bryan Bernhard, Ph.D.

North America

The Center for Veterinary Medicine at the Food and Drug Administration first issued Guidance For Industry (GFI) #191 in 2009. Over the last few years, the CVM asked animal health manufacturers to update growth implant labels in accordance with the production phases outlined in GFI #191. This created some confusion around how growth implants could be used in the beef industry.

The defined production phases for beef cattle left some lingering questions for many in the beef industry, especially with the production phase of dry lot and how it differs from growing on pasture and the confinement for slaughter production phase. GFI #191 and associated documents from FDA have helped define the dry lot production phase.

A summary of the FDA documentation defines dry lot by four criteria:

• Diet: majority being harvested forage/roughage
• Environment: dormant or completely grazed pastures OR dirt floor pens
• Growth expectations: similar to cattle on pasture
• Subsequent phase: cattle move to the next production phases to continue growing whether pasture or confinement for slaughter

These four criteria are key to understanding how the FDA considers a dry lot different from a pasture phase and a grow yard or backgrounding operation that are a subset of cattle fed in the confinement for slaughter production phase as defined by the FDA.

While cattle in a dry lot and cattle in a grow yard (a subset of cattle fed in confinement for slaughter) can both be on a dirt floor pen, the FDA has outlined differences in physiological state, diet, movement from one production phase to the next and potentially rates of growth between the two production phases.

This table summarizes the differences between a dry lot and a grow yard.

The dry lot phase is an opportunity for beef producers to add value to the cattle in their care. At this stage, cattle can come in from several sources and may not be consistent in size or health programs. A dry lot allows producers to get cattle healthy, add weight and sort cattle into uniform groups. By leveraging an implant with trenbolone acetate (TBA) in the dry lot phase, cattle can add lean muscle and hit their target weight sooner before moving to the next phase.

Earlier this year, Zoetis received an additional label indication for its Synovex Choice^® implant in the dry lot production phase, as well as gained approval on a new implant product for the dry lot, Synovex^® Primer^TM.

These are the first TBA-containing implants approved for the dry lot production phase, and it gives producers in the dry lot phase more options. Research has demonstrated that TBA-containing implants help extend the growth curve and keep cattle leaner longer as cattle get heavier.¹

In dry lot research comparing Synovex Choice and Synovex Primer with a sham implant, cattle receiving Synovex Choice gained 2.50 lb./head/day (p = 0.0016) and cattle receiving Synovex Primer gained 2.47 lbs./head/day (p = 0.0016) when compared with the sham implanted group at 2.21 lbs./head/day over the course of the 90-day study.²

Talk with your nutritionist or veterinarian about the value of including an implant in your dry lot program. For more information on the complete line of implants from Zoetis, go to Synovex.com.

Refer to individual labels for complete directions for use, precautions, and warning. Reimplant only if and as directed in labeling.