Sensory influences on homing of stunted rat pups

The effects of 2 methods of restricting food intake--large-litter rearing and rotation between lactating and nonlactating females--on sensory factors involved in homing to the nest by rat pups were examined. Homing was observed in the unaltered home cage, when olfactory cues were altered and when visual cues were altered. Stunted animals homed less in the unaltered cage than did well-nourished controls as a result of a maturational delay. Prior to eye opening, stunted animals showed greater disruption of homing when olfactory cues were altered and after eye opening they showed greater disruption when visual cues were altered. These effects could reflect decreased sensitivity, an inability to use alternate cues, or behavioral disruption by novel stimulation. Nonnutritional factors were also found to affect homing as the 2 well-nourished groups differed in their behaviors. These differences appeared to be due to animals reared in small litters maturing more slowly than animals rotated between females.