Oh Mo we are so sorry for this
Im not sure if you know this because you are farmers, but not sure if you guys put rat poison down for the farm rats?
We used to use Fresh Coke, yup Coca Cola, they drink it and they explode becuase they cannot burp. It works!!
maybe you can tell the other farmers in your area about this.
The coke it put in a pie plate and changed everyday, it has to be fresh!
I hope you can find out defintely what happened to your sweeties ((((hugs))))