MOVES by ATV to expand its midweek racing coverage have provoked concern over the effect on young viewers. Under the proposal, ATV's World channel would switch to live coverage at 8.30 pm - half an hour earlier than at present - next season. The proposal has been submitted to the Broadcasting Authority for discussion in its next meeting, but Legislative Councillor Eric Li Ka-cheung said family relations could be sacrificed if the move was backed. ''The extension of the racing programme into earlier hours will deprive children of the time for family gathering,'' he said. The programme has an average audience of 300,000 to 400,000 viewers.