Hi,
I am new to this forum, your pigs will either need an ear tag or a slap mark with your herd number on it to be able to go to slaughter.
A spray mark is ok for pigs under 6 months if they are being moved from holding to holding but is a temperary mark.
If you would like any further information about a slapkit then do not hesitate to contact me, I am a pig sales representative for msschippers UK and would be happy to help,
Regards
Kayleigh