Print the cards with a different coloured paper than the rest of the sows and put them ear tags with the same colour as the paper.
This is a usual standard on many pig farms to identify a sow with different genetics quickly.
An option to minimise the entrance of replacement sows on a farm is the entrance of grandmothers to produce our own replacement sows. Other production structures have their own selection pyramid, with different genetic lines, even within the same farm.
These sows with different genetics will have to be mated with the appropriate boar, and their daughters will have to be identified, differentiated and kept on the farm, because they will be the replacement sows when they reach the appropriate weight and they have passed their selection process successfully.
In order for all this system to work, it is very important to have this sow well identified to inseminate her with a different semen, do not dock her daughters' tails, do not make litter changes with her offspring...
With this aim, we can print these sows' cards with a different coloured paper than the rest of the sows and put them ear tags with the same colour as the paper. If possible, use a flashy colour, easy to distinguish and visible from a distance.