I've read the entire thread and rather wish the OP would return to it. Perhaps, the OP is mulling it over and will announce the outcome at a later date, but here's my take, unpopular with some as it may be:
There's also the flip side of what you said, Joe. If I moved there specifically because I desperately wanted to raise chickens and have a certain lifestyle, and legally had every right to do so, their mistake is interfering with a big part of my life. To think someone expected me to give up my own dreams when I really didn't have to do so, only because they had flubbed up royally in their dealings, just isn't acceptable to me. I'm sorry as heck for them, but it's really not my problem. Hopefully, they can work it out somehow, but without strong-arming the OP into letting go of their plans and their flock.
As a realtor, and it was stated previously from a real estate law point of view, I know that with no restrictions on that parcel of land, the OP has no legal obligation to set aside their desire to have a flock of their own. In the end, yes, it's up to them if they want to bow to the wishes of someone else, let themselves be guilted into letting go of the enjoyment of their own property.
ETA: Maybe the OP should offer the Tyson grower a chance to buy back the property, at a profit to the OP. Then, they can re-sell it to someone with restrictions in place so this doesn't happen again.
Edited by speckledhen - 5/9/12 at 8:03am