IIRC Bertie initially blamed eating at a restaurant until that resaurant said they only use locally sourced beef and there’s vey low incidence of it’s use within the EU. I think legal action was mentioned and it quickly changed to Argentinian beef from someone he knows.
That pig offal though the poor Fury’s fell foul of that too. Obviously they’re clean.
ETA: they test for synthetic nandrolone so natural boar nandrolone would be OK.