Female aggression during gestation and lactation in two strains of mice selected for isolation-induced intermale...

The present study investigated whether maternal aggression is related to male behaviour in two strains of mice selected for isolation-induced intermale aggression. The strains were selectively bred from an outbred Swiss albino stock for high (Turku Aggressive, TA) and low (Turku Non-Aggressive, TNA) levels of aggression in forty-seven generations. One hundred and forty individually housed TA and TNA females were administered a seven-minute aggression test involving adult male intruders. The aggression tests were performed on day nine and eighteen during the gestation period, and on day one, three, six, nine and twelve postpartum. Separate groups of animals were tested on each of these days. Maternal aggression was found to be related to intermale aggression in the selectively bred TA and TNA strains. During the gestation period the females of the two lines displayed differences only with regard to sniffing, whereas during lactation significant differences were observed in this regard, as well as in attacking and tail rattling. The aggressive behaviour of the TA females reached a peak on day three and nine postpartum.