Like ""Master of All Masters,"" this Scottish folktale about an obstinate cow who won't hold still for milking is a dependable oral favorite that needs no visual elaboration. Sewall's approach, in a switch from her usual sly, lively sketches, is to decorate the story with red and black stills in checkerboard tartan frames that match the wee, wee Mannie's kilt. In folklike (but not particularly Scottish) scenes of rolling hills and oversized flowers, the Mannie's ""mither"" advises him to command, threaten, coax, or bribe the Coo; alternately, the spirited Coo takes over the page and kicks up her heels in dramatic resistance. All of which does, at least, sound the perky note in an already brisk number.