Originally Posted by AEK
99% sure this is correct.
Yeah, you guys are right.
Jamón Ibérico/Jamón de Pata Negra seems to have three quality grades:
de Pienso (Cebo?): Grain-fed
de Recebo: fed with up to 30% belotta/acorns in the end of the breeding ("finishing")
de Belotta: At least 75% of the pigs have to be of the Ibérico-breed, >40% of their live weight through eating acorns and herbs plus free-range.
At least that's what German wiki says. Can't completely understand the Spain wiki, but I think the above grading is mostly correct, however some numbers and details might not be definite.