Does anybody know anything which can be done to get them back to breeding? Are they too old or could there be another reason as to why they are not breeding?
Dear Nicole,
one year old females cannot be expected to be productive...... It is something like a grandma. For males the situation is a bit different: usually they are productive until they die, although the efficiency declines.
Usually (although there might be some exceptions) changing of diet etc. does not help too much... they are simply too old.
In case you are in danger of loosing the line, put younger females (maybe in addition) into the mating cage.
Best
Volker
To give a valid answer a general question like yours is nearly impossible.
If you want to have usefull replies, be more specific:
How old are your mice, how long are they sitting together? How is the general breeding efficiency in your mouse facility?
What is the genetic background of your mice?
Did this specific breeding pair in qustion produced offsprings before?
What is the health status?...etc.
Just generally speaking: Based on published data there should be no direct effect of the genotype on the breeding efficiency.
Best
Volker
Thank you Volker for your reply,
the mice are about a year old. I now learned that they shouldn't be so old but I also read that mice can breed theoretically until they die.
We already swapped the male , we have two females and one male together. Now removed the house from the cage. I have no idea about the generell breeding efficiency in our mouse facility.
The mice are homozygous for uPAR KO and they produced offspring before, regularly. They seem to be healthy.
I also read that elderly mice prefer not to get pregnant for energy reasons, so I will try to give them high fat food so that they have an extra amount of energy to get pregnant. I will also perform a plug check.
Dear Nicole,
one year old females cannot be expected to be productive...... It is something like a grandma. For males the situation is a bit different: usually they are productive until they die, although the efficiency declines.
Usually (although there might be some exceptions) changing of diet etc. does not help too much... they are simply too old.
In case you are in danger of loosing the line, put younger females (maybe in addition) into the mating cage.
Best
Volker
Voker is absolutely correct. You need to have young female breeders to maintain your colony. You also might want to consider cyropreserving your line so that you don't lose it. Best of luck!
Larry
Thank you Shaima, unfortunately, I don't have young females. If I had I wouldn't have a problem. We are trying several things. In case I will succeed I'll let you know.
Since your mice are homozygous i.e. both alleles are affected you could theoretically cross the uPAR KO male (forget the females, they are far too old) with younger wild-type females to generate heterozygous mice, which can then be used to re-establish the colony. However, you also have to take into account the strain that the uPAR KO mice are in i.e. if they are mixed (multiple strains) or have been crossed into another background for 8 - 10 generations so that they are essentially pure bred mice of a specific strain. The strain can have huge impacts on a phenotype, which is something you want to avoid.
As a general rule, breeding females should be 'retired' and considered sub-optimal as reliable breeders around 8 months. Males can be kept around for up to a year but, as mentioned above, their breeding efficiency does decline significantly over time.
I agree with Jonathan, get some wt females and recross the hets, in the end you will save time.
Hi. We had the same problem with uPAR null. We did hete crosses as Dr Shillingford suggests.
we retire the females after they gave birth 5x. We noticed that they gave lesser number of pups after each birth.
Fenales are often used in experiments but try to keep some aside to replace/retire breeding cages.
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