[header] How to tag cattle [title] Determine the best time to tag your cattle. [step] You can apply tags shortly after birth, during the calf's weaning period, or around the time that you begin branding young or fully-grown cows. The time that you choose will depend mostly on how operations are carried out on your farm or ranch. 
For some, tagging calves at birth may make it easier to keep up with them as they grow. Others may prefer not to bother with it until a cow is headed for auction.