So, how do these new guidelines fit with my pet rats' accommodations. I have 9 rats, and they live in a Double Critter Nation (DCN) 24" by 36" by 4 feet. That's the external dimensions, so.. being cautious. They have 2347 square inches. (It has 2 floors (one of which has a 6"x9" cutout) and 2 half floors) They also have 12 inches between each floor which gives them 5 more inches of headroom than the NIH guidelines request.
This is an excerpt from our spreadsheet on our rats' weights.
NIH guidelines excerpt
http://grants.nih.gov/grants/olaw/Guide-for-the-Care-and-Use-of-Laboratory-Animals.pdf#page=83
... Now for some more math
I have 4 rats that require more than 70 square inches, 3 rats need 60 square inches, and two rats need 40 square inches. So, my rats need 540 square inches.
Hmmm... They have 2347 square inches. I do believe by NIH standards I can get a LOT MORE RATS. LOL.
By the way the DCN by the pet rat community is considered adequate for 10-12 rats. 10 rats if they are male, and 12 rats if they are female. Which means by the pet rat community, I am getting close to the max occupancy, but by the NIH guidelines, I could get 24 more rats.
But, when I was reading the NPR article, my gut was saying that something was fishy. And, I read another blog that commented that the NIH was puzzled that the researchers were upset because NIH thought everyone essentially was following the guidelines already. I reperused the NPR article and looked at the 2 cages.
HAH There it is. The old cages are 140 square inches which fits perfectly into the requirement for a mother rat and litter. The new cage is 210 inches which not surprisingly is 70 inches larger or rather the space a male rat needs. The average male rat is over 500gms, and therefore they need 70 square inches. Indeed, Doctor and Walter are both easily over 500 grams. (ok, Walter is overweight, but Doctor is a small male and weight 607 gms)
So, the researchers are leaving the Daddy Rats in with the Mommy Rats and Babies which on first glance may not be too horrible. In general though, you don't want to do back to back breeding because it is physically too demanding on the mother, but in rats, their physiology makes it even more an issue.
Female rats can have a litter every month. They can become pregnant right after giving birth. And, their baby girls can become pregnant at 4 weeks when they are still nursing. Indeed, I was recently reading on rat forums that rat breeders don't have to worry about separating the sexes of a litter so much at 4 weeks because the baby boys are unlikely to inseminate the baby girls or mother rat, but that an adult male can inseminate a baby girl rat at 4 weeks.
Rats breed when they have an adequate food supply. There's an excellent National Geographic Special about this. When rats are kept in captivity, their owners become responsible for their care and that includes birth control. If you feed them adequately, they are going to breed if you do not manage it. My 2 males are neutered, otherwise, I would never have introduced them to my cage of 7 girls.
It looks to me that the issue the researchers are having is that they don't want to have to remove an adult male rat from a mother rat and her babies.
On that note, I shall leave with a picture of my small boy rat, Doctor
Oh, and this is my set up for weighing the rats. Bittle is in her usual spot on the couch looking totally ridiculous.
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