Bignall has returned to parent club Reading to receive treatment on a hamstring problem.
The 19-year-old sustained the injury in training last weekend and subsequently missed the 1-0 victory at Tranmere on Monday.
He is not expected to return to action for County for at least a fortnight so Peter Thompson should again line up in attack for Ablett's side.
Thompson has yet to score this season, but Ablett said: "He just needs to score a goal for his confidence. Once that comes we'll have a very good player on our hands."
County are still without midfielder Matty Mainwaring, who remains sidelined after he broke a leg during pre-season.