why did my female rabbits quit concieving

Question
I have two female holland lops that are two years old.They have both had previous litters by the same buck,but the last three times they have been bred they have not concieved.Why would that be?

Answer
Dear Carrie,

There are so many possible causes of infertility in any mammal that it's really not possible to know for sure why these bunnies are not conceiving.  If they are somewhat closely related to the male then it's possible that the offspring are inheriting two copies of some recessive lethal allele, which is far more common in purebred animals of any kind.
This could cause resorption of the fetuses before they come to term.

The bunnies may also be resorbing litters if they feel stressed or unwell in any way.  Crowding, insufficient play and exercise all can contribute to psychological causes.

A good overall wellness check by a good rabbit vet might reveal a problem:

www.rabbit.org/vets

but I would recommend you read this before you try breeding them again:

www.bio.miami.edu/hare/breeding.html

I hope this helps.

Dana