Congrats on the dum!

my 2 are around the 4' mark (not sure of weight) and eat medium rats from Layne Labs. I usually feed them 1 rat every 2 weeks but I mix it up a little from time to time. Sometimes they'll go 3 weeks without a rat, sometimes they get a rat 2 weeks in a row, and sometimes they get 2 rats in one feeding.

I feed in the cage... usually grabbing the rat by the tail using tongs and shaking it in front of the snake. Dums are known to be "wild" strikers so pay attention to what you're doing because they may miss the rat and come at your hand. I've yet to be tagged by my dums, but there have been some close calls during feeding. You may be able to get away with leaving the dead rat in the cage and letting the dum stumble upon it.
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1.1 Argentine Boas
1.1 Dumerils Boas
1.1 Black Milk Snakes
2.3 California King Snakes
1.1 Nelsons Milk Snakes
2.2 Corn Snakes