In England and Wales:
bringing cattle sheep or goats onto a holding triggers a 6 day standstill on pigs cattle sheep or goats
bringing pigs onto a holding triggers a 20 day standstill on pigs, and a 6 day standstill on cattle sheep and goats
BUT as with scotland you can always move stuff to slauhghter.
The idea behind the legislation is to slow disease spread, pigs take longer to show F&M.
So if I bring pigs onto a holding, the cattle sheep or goats alreday there will rapidly show F&M if they catch it, so if they haven't shown it in 6 days then they are likely to be ok, whereas any pigs already there will take longer to show so have to wait 20 days. if I bring cattle, sheep or goats on, then the animals coming on will show the disease, so if they are well after 6 days, then they are unlikely to have F&M, so will not have passed it to pigs, so all can move. And if you take any animal to the abattoir, then it will be dead so not spread disease further!