What's wrong with them?.........
I just recently had a problem with some rats that caused me to lose a prized Boa of my collection. I tried to save a few bucks on my rats by switching suppliers and it cost me big time.
There is a rat that is a breed called a "Zucker". It is a rat with a higher fat % then your normal rat and referred to as being "obese". From what I have been told and found while researching it, its purpose of application is for insulin resistance, glucose intolerance, metabolic deficiency and genetic obesity. Bottom line this rat is loaded with FAT!
The problem is that Boas can not digest fat like a Python. You can give Pythons fatty rodents and pigs and they will do fine, give them to a Boa and you are going to have major digestive problems. The Boa will bloat up and get very gassy for starters. When it comes time for them to defecate you will find yourself cleaning up a very smelly, greasy sometimes gray colored stool if not diarrhea. Stephanie has compared it to Crisco shortening you use for cooking! This also ends up being smeared all over the cage and Boa most of the time for some reason. I believe there to be tons of Bacteria in it and it causes for a bacteria bloom inside and outside of the Boa. This is also the reason why people who get bad stools and diarrhea have a Boa go right into a shed cycle and shed out there color. Then WOW!....they now think they have a Calico Boa! LOL I am sure this has happened to a few people and they have not brought it up or figured out what actually went wrong.
The bottom line is these rats can serve a purpose for Pythons and Monitors, but for Boas I think they should be avoided at all costs! You have heard many of the stories on the forums about the boa that regurged or had diarrhea and then either died or shed out its color. Well I think this is the cause the majority of the time. You do not need to study every rodent you feed off; they really stick out like a sore thumb. I remember thawing them out and saying to myself, "Man that is a funny looking fat rat!" They are about as wide as they are long! LOL They also have a shorter snout then normal.
This is not something that builds up in the Boa over time, but something that happens the week you feed them the rats. They start to digest them and half way through have problems because of the amount of fat the rat contains. I only feed frozen thawed to my adults, so I am only referring to f/t jumbos. I do not think there is any worry in sm-mds, because the "Zuckers" seem to gain the high % of fat when they reach maturity. This is just a heads up about fat rats and the experience I had, and a few others I know of that have had problems in the past.
Remember, the Rodent Supplier has done nothing wrong as they simply supplied you with your rats. It is up to you to know what to feed to your Boas.
Hope you can learn from my loss.