My big girl that laid at the end of last month, I changed the tub and put her back and offered her a rat weanling that night. Its normally way to small for her, she was 3500 grams before breeding her. She ate 2 of those, and then for the last few feedings would only eat weanlings, yesterday she ate her first big rat. If she is refusing her normal size food you might try offering her something small that you can safely leave her with and give her some privacy to eat.