Abstract
Twenty-two-day-old female Rockland-Swiss albino mice ignored 1-day-old young. As age increased there was a decrease in the percentage of animals that ignored pups. Pup-killing, exhibited by a significant number of 32- and 42-day olds, declined as age increased. Furthermore, the number of females exhibiting maternal behavior increased with advancing age. Olfactory bulb removal and testosterone propionate treatment, each of which elicit pup-killing in adult females, did not induce killing behavior in 22-day olds. Finally, ovariectomy performed on Day 18 reduced the number of animals that displayed maternal behavior on Day 62.