And adult mouse is pretty close. An adult mouse is around 25 grams. When feeding BP's specifically you want to be feeding 10-15% of their body weight. At 280 grams the smallest prey item you want to feed (without feeding multiples is 28 grams) but for a young animal you want to be feeding as close to 15% as possible. I like to feed my babies and juvies between 3-5 days as well. This year I feed 10% of their body weight every 4 days up to 300-400 grams.

The appropriate size in rats, if feeding once a week, would be a weaned rat.

http://www.google.ca/imgres?imgurl=h...ed=0CD4Q9QEwAQ

hope this helped.