I also researched a bit and I found this: Flax Seed
Now I feel like a fool...
Making it short, it says that the best way to feed it is grinded, it's good not-grinded too, that recent research done on various seeds found that the nutrients were extracted from the seed hulls even if some seeds appeared "whole" in the manure.
That it's not poisonus like we believed, because 2 components that make cyanid don't make contact, but they do make it in water, so in water is more dangerous, but it's such a small quantity that won't do any harm.
Well, it answered my questions :P
Thanks for telling me the amount :)