title: Long-term effects of naturally occurring within-litter differences in body weight of rats.
abstract: From 10 litters of intact Fischer rats, three groups of each sex were formed on the basis of body weight at 30 days of age: Light (L), Medium and Heavy (H). Their weights were examined again at 60, 90, and 120 days. At 60 days the M animals had caught up with the H group, leaving behind the L animals which remained lighter at the end of the experiment. Starting at 63 days, the animals were given several behavioral tests. Behavioral differences between M and H groups existed at the age when weight differences between them had disappeared. The results indicate the longlasting effect of naturally occurring within-litter differences in body weight and behavior. The procedure used may help in studies of longlasting effects of early feeding.
mesh_terms: D000818:Animals; D001362:Avoidance Learning / Q000502:physiology; D001522:Behavior, Animal / Q000502:physiology*; D001835:Body Weight; D003214:Conditioning, Classical / Q000502:physiology; D014644:Genetic Variation; D006128:Growth; D008137:Longitudinal Studies; D009043:Motor Activity / Q000502:physiology; D051381:Rats; D012726:Sexual Behavior, Animal / Q000502:physiology