Kenneth MacMillan seems to expect the public to swallow the grossest forms of erotic exhibitionism and cynical bombast on the ballet stage as if they were the height of esthetic daring. That, at least, appears to be the inescapable conclusion after a first viewing of the "The Wild Boy," the latest MacMillan opus, commissioned by American Ballet Theatre and given its world premiere by ABT Saturday night at the Kennedy Center Opera House, with a cast headed by Mikhail Baryshnikov and Natalia Makarova.

It would be easy to dismiss the new work as absurd sensationalism if MacMillan were not the formidable talent and master craftsman that he is. The 52-year-old Scottish-born choreographer was artistic director of England's Royal Ballet for seven years; he still holds the post of principal choreographer. During the Royal's visit here last summer, we saw samplings of MacMillan's polar extremes -- on the one hand, his recent, highly personal, expressionistic "Gloria," which ranks, like the earlier "Song of the Earth" and "Requiem," among his most original and compelling creations; and on the other hand, the misbegotten "Isadora," which attempted to reduce Isadora Duncan to a bubbleheaded tramp.

Unfortunately, and in more ways than one, "The Wild Boy" takes up where "Isadora" left off; the extended and graphic sexual encounters could well be rejects from the latter ballet.

"The Wild Boy" opens, to the clangor of Gordon Crosse's coarsely atmospheric, neo-Stravinskian score, on a dark enclosure of jungle foliage and suspended vines (the imposing scenery is by Oliver Smith). In front of a massive tree stands Makarova as The Woman, in toe shoes, a turban, and a sheer, skimpy garment of indeterminate period and place. The two men who enter looking like brigands are her Husband (Kevin McKenzie) and his Friend (Robert La Fosse). The Woman is tossed from man to man, and the men wrestle in a manner that suggests both sensuality and hostility -- an all-purpose me'nage-a -trois. Enter the Animals -- 12 male dancers costumed as slavering jungle cats, who grovel about and do rutting push-ups and headstands. Into their midst bounds the Wild Boy (Baryshnikov), as close to naked as the stage permits, though he wears dance slippers; he crouches warily, chomps food from the ground, and dances a big, apish solo with the Animals. Then he's snared by the two men, who, with the Woman's help, proceed to abuse, kick and beat him.

The two men wrestle some more; when they exit, the Woman undresses and mock copulates exhaustively with the Wild Boy, rolling around in a supine tangle as the Animals watch furtively from the bush. The two men return to excoriate the Woman and attack the Wild Boy, who retaliates by bashing the pair's heads together in what suddenly turns into a homoerotic kiss. Blackout. The two men now drag the Woman to the floor, and all three collapse into fetal heaps. The Wild Boy returns, in some shreds of clothing and reeling drunk, flask in hand. He drops the flask, disrobes and plops to a sit. His erstwhile Animal companions reject him, and he withdraws his hand painfully from grabs at the earth, as the music dribbles down and the curtain falls.

The subject of a wild child reared in the forest who undergoes a traumatic encounter with civilization has attracted artists before -- most recently, filmmakers Francois Truffaut and Werner Herzog. Usually the point has been to explore conflicts between nature and society, but MacMillan seems bent solely on expressing his loathing for both. Aside from the attempt to outdo Glen Tetley in lurid calisthenics, there's little of choreographic interest in "The Wild Boy." One can applaud Baryshnikov's aggressive new acquisitions policy in commissioning this and other new works this season, and one must admire also the grim fervor and mordant characterizations of the principals in the first performance -- Baryshnikov's anxious proto-humanity, Makarova's viperish lechery, and the surly sexual ambivalence of McKenzie and La Fosse. "The Wild Boy," however, is a loser; one can only hope MacMillan has gotten this stuff out of his system now, and can get back to making ballets.

The evening had compensations. Marianna Tcherkassky and Danilo Radojevic were sweetly agile in the new staging of the pas de deux from "Flower Festival at Genzano," though the crisp attack and open torso of the Bournonville style weren't completely in place. In the season's first performance of the Kingdom of the Shades scene from "La Bayadere," Martine van Hamel was at her expansive best, and Patrick Bissell danced expertly, if with little awareness of the scene's dramatic import. The program began with a splendid account of "Jardin Anime" with Susan Jaffe and Lisa de Ribere as the sparky soloists.