Implanting nursing calves has consistently shown to be an effective way to post greater calf weights at weaning time. In fact, Grady Ruble says implanting has the greatest return on investment of any other technology.
. . . deciding to implant nursing calves is more important than which implant to use.”
Source: FEEDLOT, March 22, 2023. Link. Generally, branding makes for a convenient time to administer suckling implants.