Maybe I'm being a conspiracy theorist, but if this attorney who has an issue with hogs on the property showed you documents from the courthouse, where he likely knows the judge, notary and whomever else is involved with said documents, I'm with Flower on the possibility he's jerking your chain. And GAM is right also, attorneys make mistakes, banks make mistakes. I smell a rat, though. If there isn't any record in the courts that that was a requirement for sale then what can he legally do if it is YOUR property now? And who the heck gives him the right to tell another person what they can and cannot do after the fact?
As far as the lame argument about "city folk" might not want hogs around? Ridiculous. He "Said that the hogs on our land would make it harder to sell his land". Ok, well how can he possibly state that as a fact when he has NO IDEA who might possibly show interest in the property that he has not yet listed for sale? There are too many variables here and as far as that statement, it's his opinion. A statement in which the burden of proof is on him and how on earth could he possibly presume to know what decision a buyer is going to make? Is he psychic? We're "city folk" who bought property in a rural area (I'm assuming said property in discussion is rural) and did so with the full understanding that there would likely be ALL MANNER of critters, sounds and smells that are perfectly NORMAL in a rural area, that we may not be accustomed to. He's grasping. If any "city folk'' had such issues, they wouldn't be buying in a rural area. Especially if it's acreage involved. The perfect buyers may just turn out to be "city folk" who want chickens or hogs of their own. All things that nobody could possibly presume to know because none of those factors are in play yet. And even if it did devalue his property, it wouldn't be by much I would think. Not to constitute a major loss, anyway. I think he's using the fact that he's an attorney to simply intimidate someone who may not know the ins and outs like he does. The best defense is a good offense. I think calling that 1-800 number is a good idea.
I agree with GAM, Flower and Katsdar. Don't make any moves yet as far as making concessions until you do your homework and find out exactly what rights he has to impose such things and what rights you have regarding your animals and what is now your property. Especially if you are making any income from them. He's worrying about property devaluation but what about losses of income for y'all? I sure hope that there are some loopholes that pop up in your favor and that a suitable agreement can be made that benefits all parties involved.
His actual words were: "If somebody from ATLANTA comes here to look at our house and sees your pigs right next to our land it could influence their choice." 
