http://www.mangago.zone/read-manga/mori_no_animal_company/
When you say black and white. It reminds me of this. They're mainly about cats though.
Maybe the wild series; http://www.mangago.zone/read-manga/wild_fangs/
http://www.mangago.zone/read-manga/wild_fangs/
http://www.mangago.zone/read-manga/wild_rose/
They aren't sheep and no prince. But they are beasts. I'll keep looking
http://www.mangago.zone/read-manga/tatsu_no_otoshigo/ (the boy has horns. Sort of a God than a prince)
http://www.mangago.zone/read-manga/mayonaka_no_acchimono/ (this is a goat demon and fire god)
http://www.mangago.zone/read-manga/nigeta_hitsuji_no_tsukamaekata/ (he has Ram's horn)
http://www.mangago.zone/read-manga/mahoroba_days/ (A deer deity)
I hope one of these hits the mark.
Thank you for your answers ! That's not what I'm trying to find but I'm still gonna read what you recommended ! :)
sorry I couldnt help. However do check out Kathy's list and maybe you'll find it there ; http://www.mangago.zone/home/mangalist/934/
It's okay ! I finally found it ! And I was wrong it wasn't sheep xD
http://www.mangago.zone/read-manga/ookami_wa_koi_ni_naku/
I want to find this yaoi manga, but I dont remember much. I think it was about animals maybe sheep and there was the black one and the white one and there was also something about a wedding. and I think but im not rely sure there was a prince theme ?