Send her a bill for boarding them dated from the time you first asked her to come get them. She is using you. Send that to her with one last request to come get them. Tell her in the letter that if she doesn't retrieve them by X date that you will consider them abandoned and will keep them as payment for the back boarding fees. Post it on Facebook, through email and through a registered letter if you know her address. The ads in the newspaper are good too. If she has not retrieved them by whatever date you pick, then they are yours to dispose of as you see fit. Keep them as your goats or sell them to cover the costs so far. She has been told and fairly warned. If it makes you nervous, you might check with your local police or sheriff to make sure of the legality of it all.
She is using you for free room and board. Don't let her. Be firm. Be precise. Be clear about what you expect and when you expect it.