Reptile & Amphibian Forums

Ive been breeding rats for almost a year now. They were originally my pets.
All my litters have always been roughly 7 to 8 pups. WIth the occasional 10 pups.
They are all from the same genetic line until recently, I bought a brown rat from a feeder bin. She is now 4 months old and just had her first litter. 14 pups. Ive heard this is common, just never saw it myself.
The father was the same as the 2 moms who just had 8 pups.
So Im wondering is litter size genetic through the mom?

If so Ill add 2 of her girls to my breeding pool (otherwise I have plenty).

What are your thoughts?
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1.0.0 YBS
1.3.0 RES
1.0.0 red belly cooter
1.0.0 Fire belly toad
0.0.1 Savannah Monitor
0.0.1 Blackthroat monitor
0.1.0 Leopard Gecko
cats, dog, ferret, rabbit, rats, mice and hamsters

I'm not an expert in genetics, or rat breeding, but I've bred rats for my snake colony, and from what I've seen, a resounding yes.
In both strain, and selective breeding in individuals.
I had a mouse colony for years, and I just let them inbreed until they were no longer suitable, then killed them all off and started over with a fresh batch from different sources.
I had a few males pop up in the colony that had exaggerated features, and it turned out they were beginning to show signs of dwarfism, including smaller litters in the females. All my males turned out to be these dwarfs, and they were the only males contributing to the breeding brogram, so it was only a matter of time before the whole thing went too far off the deep end. So, it goes through the males too, but on a somewhat lesser scale.
They all went in the freezer, and I fed out the contents of the freezer, and restarted the program with fresh blood.

Oh, and in the rats I currently have, the whole group is due to be put down for the winter, but when the group was fresh they were a minimum of 10 to a litter, with the average being 12-14, depending on the female. Mine were slower cyclers, so they were about 23-24 days instead of 21-22. No idea why. Maybe my males were slow. *shrug*
Now they're doing 7 or 8 per litter, and 10 is the max, so it's about that time. It's almost time to put the snakies to bed, and I can certainly survive off what's in the freezer again until next spring, so my course of action seems clear.

Litter size is based entirely on the strain of rat that you breed. Sprague Dawley and Harlan Tecklad rats are prolific breeders commonly producing 12-15 baby litters. I average 13 with my colonies every 3-4 weeks from any given mother.
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www.strictlyballs.ca

>>What are your thoughts?

As mentioned it has to do with genetics, same reason some families are prone to twins. Although that's not the same process exactly.

Although age plays a factor as well, as a female rat gets older she will gradually drop smaller and smaller clutches. Although a small clutch can be a problem with the male as well.

Cheers
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Jeremy Payne
JB Reptile
Specializing in Boa Morph's

1.0 Snow "Kahl"
0.2 Triple Het Moonglow "Kahl"
0.1 Orange Tail Hypo Het Leopard
1.1 Double Het "Sharp" Snow
1.0 Ghost
0.1 Possible Super Hypo
0.1 DH Ghost
1.1 "Kahl" Albino
1.0 Hypomelenistic
1.3 Pastel Hypo
0.1 Suriname/Columbian cross
0.1 Anerthrystic