ST. LOUIS (AP) _ If not for an early twist of fate, Tony McKegney would probably not be plying his talents in a sport that is essentially all white.

But by capitalizing on circumstances known by few, he has become an example for blacks who would aspire to playing in the National Hockey League.

''I was the second to be adopted,'' McKegney, a St. Louis Blues forward, said of the white family in Sarnia, Ontario, he became part of before he was 1 year old.

''My parents had three children of their own, and they adopted three children,'' he said. ''My dad felt ... he could do something for the amount of kids that were homeless or without parents per se.''

McKegney recalls no special obstacles for him or his two adoptive brothers, who are also black, as they were growing up with a racially mixed family in a city of 50,000.

''It seemed very normal to me, and no one in our neighborhood or city really treated us any different,'' he said. ''But I think sports probably helped a lot, because we were known as athletes and so forth. People had a certain amount of respect for us athletically.''

McKegney vividly recalls the support from his parents - Lowry McKegney, a retired chemist, and Cathy McKegney.

''I remember the dedication that my parents put into it when we were younger, driving us to rinks at 7 in the morning,'' he said. ''We had a hockey rink, actually, in our back yard that my parents made each year.''

McKegney was 20, playing junior hockey for Kingston in the Ontario Hockey Association, when the Buffalo Sabres made him their second-round choice in the 1978 draft.

Since then, he has played for five NHL teams - Buffalo, Quebec, Minnesota, New York and St. Louis - scoring a career-high 37 goals in 1980-81. With St. Louis, a team decimated this season by injuries, his presence has been more valued than ever was expected. Approaching the All-Star break, McKegney led the club with 26 goals.

''I think his biggest value to our club has been his ability to score,'' Blues coach Jacques Martin said. ''I don't have any theory why Tony has played with so many teams. Sometimes what has been said in the past is that once he's established he doesn't produce as much. The key is for him to keep working.''

It is the 10th NHL season for McKegney, who will be 30 on Feb. 15, and one that he would like to make his best.

''The funny thing is that I'm starting to enjoy the game more than I ever have,'' he said. ''Obviously, I know I'm on the 'back 9' - if you want to compare it to golf. I'd like to make the best of the last couple of years.''

Part of the reason McKegney wants to continue a while longer is because of sons Daniel, 2 1/2 , and Robert, 7 months.

He would like for both to be able to remember their father in an NHL uniform. He is also aware of his role-model responsibilities as one of only five blacks currently playing in the league.

''I guess, if you could say, the guy that's done the best is probably Grant Fuhr,'' McKegney said of the Edmonton goalie. ''He's had the most success. I take my hat off to Grant. He's been an All-Star. He's won Stanley Cups.''

Other blacks are forward Dirk Graham of the Minnesota North Stars, goaltender Eldon ''Pokey'' Reddick and forward Paul Neufeld of the Winnipeg Jets.

''I pride myself in being maybe the first black player to play consistently in the league,'' McKegney said. ''There were a few other (skaters) that were sort of up and down.''

McKegney has remained in the NHL largely because of his skating skills, his durability and the steadiness he mentioned.

Only once has he played in fewer than 60 of the regular season's 80 games. Two years ago, when he scored 15 times and had 25 assists, was the only season he scored fewer than 23 goals or compiled fewer than 45 points. He has three 30-goal seasons

Economics and demographics - there are far fewer blacks in his native Canada than in the United States - still keep blacks from following him to the pro ranks.

''It's a very expensive sport, and it's more of a suburbia sport,'' McKegney said. ''Until we get rinks in the inner (American) cities, I don't think that's going to change.''

While in Minnesota, he joined the late John Mariucci and Cal Peterson to form an inner-city hockey league for youths.

''It's basically black children. They started out with walker-type things out on the ice, and then they graduated to the point where they were scrimmaging,'' McKegney said.

McKegney, while striving to help provide black youths more opportunity, will never forget the chance given him by Lowry McKegney, 70.

''If I could be half the man my father was, I'd be doing pretty well,'' he said. ''I feel that I had a pretty good upbringing. That's basically what got me where I am today.''

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