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Need advice on keeping size

1181 Views 5 Replies 4 Participants Last post by  Matt Haslam
I decided in December to try and breed for better size in my mice. My mice are all skimpy small pet shop stock, but one of my original does is quite noticeably larger than my other mice. When I bred her, her four daughters retained mom's size. The original doe is too old to breed from again, but I bred two of her daughters, and I plan on taking the best son from each of those pairings and breeding back to their mothers. After that however, the mothers will be too old to breed again, and I'm unsure how to proceed. Asuming I've managed to retain the size I want, I'm thinking my best bet would be to breed brother and sister at this point?
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I'd breed brother to sister, and be sure to cull the litters heavily and early, down to 3-6 babies by day 5 or 6 (this is very important). Even when you cull heavily, though, you'll still see some variation in final adult size. Keep the biggest and breed them together. Repeat over and over, never going over 5 or 6 babies in any given litter.
Cull pinkies by skull size, keep the ones with the widest skulls and whiskerbeds and cull the ones with the small, thinner skulls. Then when the've grown up breed only the biggest adults (by length, not weight) You will see a significant improvement in a couple of years.

Sarah xxx
These methods work:

cull for size young.

feed a good mix.

get stock of a bigger size.

the last option works fastest :)
Thanks for all the good advice! I shall be putting it into practice. Shiprat, the last bit s my favorite, but has been the hardest to follow. Up until last weekend the closest breeder I could find to me was 14 hours away. But I just discovered one who is only 7 hours away, so hopefully this spring I'll be able to make the trip and get bigger mice! Yippee!
yeah, unfortunately if you don't have it in your genepool, getting bigger mice is limited unless you have a spontaneous mutation lolz.

you will increase the size of your mice with the methods described by Jack and Sarah, but i was speaking to someone at a show on Sunday and they had so far to go to improve the size, that the only realistic option was to wait until they could get bigger stock.
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