glentarki after 4 days the vet uses Anastetic(a local injection)
boar taint is found in entire male pigs that are mature(IE sexually active)
some people can detect its smell either raw(when butchering the animal) or when cooking
now just because it appears that a minority can detect it it does not mean it does not exist(just because some people can identify an engine by the note emitting from that engine does not prove that they are in some way of the mark)
once it has been pointed out to you the smell of boar taint you will recognise it thereafter
to take this further some tups if slaughtered when they are sexually active have a similar taint
now the next question is why not leave the pigs to they are outwith the breeding season this only works if the boar is slaughtered at 6 months or younger WHY because pigs can breed all year round also once they go over 120kilos there are few slaughter houses that can take them and any that do normally export them to Russia and the Baltic states
now do want to be left to devour 300+kilos of what could be tainted meat i did hear of somebody that fed his pigs only cauliflower and when cooked even his dog would not eat the meat
hope this answers you query 
Were are allowed to do this on the farm until day 21 and then it becomes a job for the vet. Too , Too , Too big I am afraid to say. done on day one when first born best time to do
them. If I miss the day then they are not done at all, but go through the system as an entire boar but only to pork. Dont do bacon any more....too hard,(not 21 anymore) but yes do barrows and only do to order each year.
