1. Tips for Successful Breeding Colony
OLAR Breeding Core
University of Colorado Denver AMC
Tips for Successful Breeding Colony

2. Breeder Facts Breeder Facts: General for Mice & Rats
Ages for setting up breeders (vary depending on strain)
General for Mice & Rats
Females: ~5 weeks and can continue to ~8-10 months.
Litter sizes will decrease as female ages around 6 months
Females not mated before 4 months of age may have decreased fertility
Males: ~6 weeks and continue until ~12-18 months.

3. Estrus Cycle
Both mice and rats can start estrous around 35 days, cycling every 4-5 days with estrus lasting about 12 hours.
Visual of cycle
Diestrus
Proestrus
Estrus
Metestrus

4. Estrous Cycle Vaginal swabs smeared onto slide under microscope
Visual of cycle

5. Breeding Setup
New breeding pairs should be set in a clean cage or female(s) may be placed in singly housed male’s cage
Pheromones in cage can place female in estrous quicker
Provide Breeder Chow
2919
Add Enrichment
Brown paper shred
Toilet paper roll
Hut
Place “Check for Pups” Card on Cage

6. Lithgow Cards
Lithgow “Check for Pups” cards are provided in housing rooms
On the back of these cards you can track births, pups lost, and successful weaning. A female can be retired by tracking the decrease in her fertility (indicated by increasing time between litters and / or decrease in average litter size)

7. Types of Mating's Continuous pair mating Pros Cons
Post-partum estrous cycle, litters every 21 days
Cons
Overcrowded cages, possibility of two litters in the cage
Non-Continuous mating
Better pup survival for difficult to breed strains
Miss female’s post-partum estrous

8. Types of Mating's Continued
Triad mating
2 females with 1 male
Pros
If females are sisters, synced estrous cycle
Two females can remain together to help raise each others litters
Male has to be removed
If more than 14 pups you must contact a vet tech
Cons
If females are not related, usually 1 dominate female gets pregnant
Must remove male from cage
Male can be rotated between females in different cages
Requires protocol approval
Harem mating
3-4 females with 1 male
Only allowed if pups are used before live birth

9. Plug checks Timed Pregnancies Set pairs day before
Check for plugs early next morning (6-7am)
Day plug found equals day 0 of pregnancy
Separate male from cage if plug found
Finding a plug does NOT confirm pregnancy only that the mice mated
Maybe cheaper and less time consuming to order timed pregnant females from approved vender

10. Things to Know About Your Housing Room
Light cycle, temperature and humidity are controlled in housing rooms
Breeders should be placed in areas where there is the least amount of disturbance- if possible away from doors/ATS’s and on the bottom row of racks
Avoid dark cycle interruptions.
Mice usually mate 5-6 hours after dark cycle begins
No access to rooms 8p to 6a
2919 (Breeder Chow) offered at no additional charge
Increased protein and fat for nursing moms
Available upon request
Flag your cages with an “Extruded Diet” Lithgow card and mark “Breeder chow”

11. Enrichment Enrichment helps decrease stress and increase pup survival
Mouse huts/paper towel rolls
Con
Female(s) can hide from male
Can also use to attack other mice
Brown paper shred
Manage their environment
Mimics natural nest
Must dispose of before cage wash
Harder to see litters/health check
**Available upon request**

12. Breeding Concerns
Many rodent colonies experience a drop in production during winter months (October-March)
May result in smaller litter sizes, irregular estrous cycles, and lower conception/wean rates
If your colonies regularly experience this drop, you should set up additional breeding pairs around September/October to ensure a continuous supply of younger breeders during these months
Non-productive breeders
Remove from colony if:
No litter produced within 60 days from original mating
90 days for “slow starters”
No new litter 60 days from last born date
No weanlings survive from 2 consecutive litters

13. Breeding Tips
To retire old breeders, set new breeding pairs a month prior to ensure successful breeding before ending old pairs
DO NOT retire old breeding pairs until you have new litters
Staggering your setup of breeders can help to ensure that you always have a pair producing
New Breeders should be setup when your current breeders are about 6-7 months old
Old breeders should be retired between 8-10 months

14. How to Maintain a Line Set-up 2-3 breeding pairs
Non-continuous
Set-up new breeders using weanlings
New pairs should be set when pups are 6-8 weeks old
Keep one cage of 4-5 males and one cage of 5 females for future breeders
Remove retired breeders and any extra mice from the colony
Maybe more cost effective to cryopreserve

15. Maintaining a Litter Reduce litter size
Limit competition by:
Sex
Phenotype
Early genotyping
Avoid any disturbance of litter
< 4 days old
Cage changing
Transfer at least half of the old nest with the pups
Keep environmental noise levels “even”
Consider fostering litters for difficult strains

16. Cross-Fostering Litters
Donor and recipient litters should be within 2 days of age, and neither litter should be more than 4 days of age, for best results
If possible cross-foster strain to strain or use a recipient strain with a different coat color from the donor strain, for easier identification of the cross-fostered pups
Outbred strain such as CD-1, ICR, or Swiss, tend to make the best foster moms
Remove the recipient mom from her cage
When you pick her up, try to get her to urinate on the pups

17. Cross-Fostering Litters cont.
Remove some (or most) of the recipient’s pups if she has a large litter
After cross-fostering, the total number of pups in her cage should be approximately the same as original litter
Mingle the transferred pups with the recipient’s pups and rub them with dirty bedding from the recipient’s cage
Return the recipient mom to her cage and place it back on the rack
Observe the recipient cage 24 hours after cross fostering

18. Troubleshooting
Stress to females can cause pup death by neglect or cannibalism. Some examples are:
Disturbing the cage(s) frequently
Vibrations and loud noises
Removing male right before or after pup birth
Separating females from cage right before or after pup birth
Manipulating pups- touching pups within a week of birth.
*Please remember that you must remain compliant with the IACUC rodent overcrowding policy. *
Do you know the most common reason why mice do not breed?
Same sexes

19. External Factors
Problems with breeding can be due to external factors such as:
Odor from staff (heavy perfume/cologne, cigarette smoke, cats)
Volume of conversations/music in the housing room
Shoving cages into cage slots anywhere on the rack
Place experimental mice on non-breeding racks if possible
The number of lab personal working in the room daily
Inexperienced /unconfident handling of the mice
Entering the housing room after hours (8p-6a)

20. OLAR Breeding Core Our Group
The Breeding Core is a group of 8 team members
2 Breeding Specialists (BC2’s) that help the labs setup and maintain their breeding colonies
4 Assistant Breeding Specialists (BC1’S) that maintain their own housing rooms and complete the breeding work in their rooms and a student worker
A Manager that meets with new labs and discusses breeding needs and concerns

21. What We Do
Set-up new breeders and advise the labs when to replace old breeders
Wean, tag and provide snips to labs for genotyping
Footpad tattoos and snips up to P9
Provide breeding updates weekly
Provide a monthly census on animals 90 days and younger
Euthanasia's
Breeding core animals
Retired Breeders

22. OLAR Breeding Barrier R2 Suite 4
A shower in suite only accessible to the Breeding Core
Quiet
Low foot traffic
One designated BC1 per breeding room
Transfers to RC1 on Thursdays
No additional testing or paperwork needed

23. OLAR Breeding Core Cost
Breeding cost: $30 per mating/successful litter
If triad mating is requested, each female will get an individual mating number and be charged a $30.00 mating fee
Includes:
Setup of breeders
Weekly monitoring of colony and database management
Managing breeders includes
Enrichment, +/- separating male and weaning pups
Detailed record keeping
Euthanasia of any mice handled by the core
Mating cards are placed on the cage
Pups are weaned and ear tagged, their ear tag number, DOB, and breeding number are recorded on an ID card

24. Example OLAR Breeding Summary

25. Example OLAR Census

26. Special Requests and Breeding Services
Weaning, ear tagging, paw tattooing, snips for genotyping and plug checks
$36.32/hr (Tech Time)
Additional tissue sample taken from ear
General training on breeding colony management
FREE
Troubleshooting for breeding problems
Rodent breeding information resources
Other services as requested

27. Rodent Breeding Information Resources
Vendors
Jackson Lab, Charles River Lab, Taconic, and Envigo
Colony management websites
SoftMouse.net
Mousecolony.com
OLAR Breeding Core

28. OLAR Breeding Core

29. Special Thanks BC1s Student worker OLAR management Our labs
Arthur Vigil
Jenette Skees
Michelle Mangette
Brittany Lebere
Student worker
Sarah Railsback
OLAR management
Our labs

30. Questions
For information or questions on breeding services or training/help needed please contact: