Like the saying goes time is money....A usual asf adult could be anywhere 70-90 grams but takes a great amount of time to get there...Usually the groups are small like a 1.3...A small rat in one month is that size already specially the males that grow quicker and are the ones you want to feed off cause they smell more.You can build a concrete tub rack that holds 5-6 levels and keep a 1.5 ratio and have rats available every time,specially if you have big females that can take 3-5 small rats at a time....