Massive rat die off - No idea what the cause is.

[Anatopism]

As of a few days ago, we've been losing adult rats left and right. The babies seem fine. Rats will seem perfectly healthy, then within a matter of hours start showing signs of physical sress, and are dead anywhere from a couple hours to a day later. I pulled out 4 dead adults this morning. 3 two days ago. 6 a day before that.

It's making me believe it may be disease/illness, as nothing has changed (except for a mixture of straw with their normal bedding in one rack, but the issue spans over all racks, and straw was replaced back to pine more than a week ago).
- I'm having 1 baby die to every 4-6 adults
- Each rack has it's own watering system: 2 have a gravity feed/valve system, the big-tub rack has water bottles for the time being.
- The Norways are the ones dropping, the ASFs al seem healthy and lively, no deaths.
- It's been in the 50-70 degree range the last week (moreso on the colder end) and on the warmer days I've cracked the garage door open, and it has not been too warm for them.
- We have chickens and ducks also in the garage, on the same bedding (pine), drinking the same water, showing no illness.
- We rotate in new blood every few weeks, but none have been added to the colony recently.
- We have fed off some of the babies to some of the snakes (before we realized it was an actual problem and not just a fluke of a couple old rats), and the snakes (adults and hatchlings) have shown no issues. Despite this, I'm afraid to feed anybody off unless I can pinpoint exactly what the problem is. One thing to lose a rat colony, another to lose all the snakes as well


Going to see if I can't do a huge clean of the entire system, add some ACV to the water, and talk to our vet about a huge dose of antibiotics. At the rate we're going, we'll be out of adult rats in antoher week or two, and we have 50+ mouths to feed weekly. Had a perfect system, even excess.. and now this. Ugh.

I appreciate any critical thinking, and really hope I can get this fixed. Not looking forward to starting up a new rat colony from the ground up.