Re: Gerbil Breeding Difficulties

[g. m.]

Sometimes, poor fertility is due to males developing between two sisters
in the womb or females developing between two brothers.
Julian has references for this. Pub med has some also.  See--
http://www.ncbi.nlm.nih.gov:80/entrez/query.fcgi?SUBMIT=y

Another possibility is they are the same gender and are marking each
other or the female is menopausal.

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