The influence of husbandry schedules on the number of embryos collected from superovulated mice.

We undertook this study to assess the effect of urine and fecal contamination in the cages of male mice on embryo production in females placed in these cages for breeding. Each superovulated female was placed with a stud male in a cage that was cleaned at 1, 24, or 168 h prior to breeding. Approximately 41 h after mating, embryos were flushed from the oviducts, and we determined the number of embryos and their developmental stages for each treatment group. The number of two-cell embryos collected did not differ significantly when cages were cleaned 1 or 24 h prior to mating the mice. However, significantly (p < 0.05) fewer embryos were recovered when cages were changed 168 h before the animals were mated.