Reaction of rat mothers to experimental disturbance

Litters were either handled (LH), or mother-only handled (MH), or left undisturbed (NH) on six daily sessions after birth. They were observed on the 7th day, after all pups had been handled, and cross fostered to give litters split so that half the pups had experienced a different, and half the same, experience as the natural young of the foster-mother. Mothers did not distinguish between young having different histories. NH mothers reared more, and spent more time retrieving pups, than the other groups. Handing thus has a direct effect on the mother. It increases maternal activity but not necessarily maternal care.