Abstract
A total of 43 female mice of different strains (AKR/J, BALB/c, C3H/He, C57BL/6, DBA/2J, and ICR/JCL) were tested four times in the virgin period (two times each in estrous and non-estrous stages), three times in the pregnant period, nine times in the lactating period, and once on the next day of weaning. On each test, a male ICR/JCL mouse was introduced into the female's home cage and the social interaction between them was observed for 10min. Darting, Chasing, Attack, Biting, Wrestling, and Boxing were checked as the female's aggressive behavior. It was found that (1) females exhibited very little aggressive behavior in the virgin period in both estrous and non-estrous stages, (2) females of several strains showed intense aggressive behavior in pregnancy, (3) during the early lactating period, females were most aggressive, and thereafter the amount of aggressive behavior gradually declined, and (4) on the next day of weaning, no females exhibited gressive behavior. The behavioral pattern of aggression was very different among the strains, even though they displayed about the same level of aggression.
