Cross-fostering in the rat performed shortly after delivery: description of the procedure
This paper describes a cross-fostering procedure in rats performed shortly after delivery, The aim of the procedure was to create groups of offspring that were exposed to a lipophilie test chemical exclusively in utem or through lactation, in
addition to a control group. Time-bred dams were watched during delivery and their litters were exchanged before the young started to suekle. All dams accepted their role as foster-mothers. We had no previous experience in performing this kind of study. The following precautions taken have probably contributed to make a successful crossfostering: It was restricted access to the animal facilities during the gestation and lactation periods and only a limited number of persons performed the experimental procedure. The dams became used to handling during the gestation period. Dams were temporarily removed from their litter and cages about three hours after delivery and just before they started to nurse the young. The newborn pups were kept warm and cleaned during the switch of cages. Dams were returned to their home cages containing foster-pups. It was a minimum of physical disturbances during the delivery and the person who performed the cross-fostering was familiar to the animals through previous handling. Twenty-nine litters were successfully crossfostered.