Methods for obtaining neonates of known age from the Virginia opossum (Didelphis marsupialis virginiana).
Postlactational estrus occurred in the opossum 6-17 da (mean 10.08 +/- 3.2da) after sucklings were removed from the pouch 1-60 da postpartum. This estrus occurred somewhat earlier in females whose young were removed later than 24 hr postpartum, rather than within the first 24 hr. Thirteen litters (37% conception) resulted from 35 initial attempts at breeding during postlactational estrus. Three of 5 females conceived when litters were removed twice in succession. The tendency forindividual females to bear large or small litters was sustained regardless of conventional or postlactational breeding. Continual rebreeding of the opossum after removal of nursing young may increase the yield of known age neonates for experimental purposes.
Age Factors↗