Interesting design. Like what you did with the hair.

Pretty drawing, but cows don't have cloven hooves. ^^;

Looks like something farm boys can finally get their kicks off to. XD

Works well as an illustration but I don't think too many would want a cowgirl toy.  I could be wrong, some Iowans might want it....badly. 
Her upper body feels rather fishlike perhaps giving her some horns would help tie her together or cow ears to make it seem not as mermaidish.