10 tips for starting your breeding program

Starting a breeding program can seem overwhelming if one is not properly prepared. Here are ten important things to consider before expanding your colony: 

1. Have a plan 

Before breeding, make sure you know which strain you want, the genotypes you want to produce, the number of mice you will need for both experimentation and strain maintenance. Breeding agreements are one way to collect and solidify the needed information.  

2. Obtain multiple breeding pairs when establishing a new colony

Adding additional breeders can significantly speed up the time it takes to expand your colony.  

3. Mate mice early  

Mating mice at an earlier age (e.g. 6-8 weeks of age) can be beneficial in growing your colony. Heavier mice, or those mated after 12 weeks of age, have been proven to be less productive.   

4. Replace non-productive breeders  

If breeders have not produced a litter within 60 days of starting to mate they are likely incompetent breeders and should be replaced to maximize production.  

5. Retire breeders early on  

Mice reach reproductive maturity at 7-8 months of age. It is recommended that breeders retire once reproductive maturity is reached, and replaced with younger mice in order to maximize colony production. 

6. For breeding consistency

Stagger breeding pair ages so they do not all retire at the same time and to help avoid slums of non-productivity.

7. Know your mice

Strain genotype (knock-out, knock-in, hybrid, etc) and phenotype can have a big impact on breeding so know when they are best to breed and the environmental factors required for success. 


8. Breeding environment is as important as the mice themselves 

Light cycles, temperature and humidity, rack placement, noise levels and even personnel can have a dramatic effect on breeding. Consistency is key.  


9. The breeding cage, enrichment and breeding support

The breeding cage is an important part of starting a colony. Each cage should have a hide and material for nest building. Extra enrichment, dietary and nutritional support as well as other aides can be given to cages of sensitive breeding mice when needed to maintain consistent breeding.  

10. Consider cryopreservation 

Consider cryopreserving your unique strains and refresh inbred colonies regularly as a preventative measure against genetic drift, natural disasters, breeding errors, or disease outbreaks.