Bryan, the Fontenot song made me think about it. So,
if it is La betaille (female/cow= La), could be pronounced like LáBéTaiéé,
Les Haricots also became Zydeco, so I'm puzzled.
I remember Alan Lomax saying that yippietaye (or something like that had a acadian/canadian origen.
I never thought about that, and I dont know the ins and outs of French grammar, but the ending has more of what I would consider a masculine sound. We pronounce it "la bétai".
Alan Lomax made a few speculations on his documentary that probably cant be proven either way, that's one of them. Still about my favorite documentary though.