I'm not opposed to a bovine option, though I think something rather more generic like "wild bull" or maybe "bison" might have been more compelling. Nothing against cows, or roleplaying Pasiphaë all we like, but it feels pretty niche. I like the race specific idea for flavor, even if its just a reskin on the fur or something. Underdark races should just have a special insect type or something, or at least animals that burrow or make dens or something. Or I don't maybe just call it a Rothe instead of a Deep Rothe so we could have a couple types. Maybe the Deep Rothes have a particular color scheme whereas the northern surface variety Rothe has something else? I'm certain they just put it in for the Salvatore books and the old 2nd ed Drow supplement, but I can't recall seeing any in Urst Natha in BG2, but maybe just because they were forgettable. I thought they were supposed to be more Ram than Cow?