We saw that somewhat, but could they really be eating all these Goa'uld symbiotes? We're talking about massive numbers here, but only a handful of System Lords to do the eating. Even expanding it to the lower lords, that's still in the hundreds. There's just not enough of them for that. Also, that just doesn't make any sense to be keeping their entire species down like that.
My impression of that event was that the symbiotes they had there were under a death sentence for a crime or something like that or that this sort of thing was only done in ritual among the council of the system lords. Daniel called it a sacred ritual - which could not explain the disappearance of so many symbiotes.