Relations between birth weight and learning ability in young rabbits.

Performance on visual discrimination learning was studied in 41 rabbit pups mainly in relation to their birth weight, but also as functions of their neonatal motor development and weight gain between birth and training time. Partial placental vascular ligation was performed on some fetuses to increase the number of small-for-gestational-age pups. No relation was found between learning ability and either birth weight or rate of motor development. Low birth weight showed some association with slightly delayed motor development, but resulted in no lasting motor handicap. Between two subgroups of low birth weight pups, those who showed substantial weight gain by training time learned faster than those who remained relatively small.