Abstract
Experience in building nests and caring for young is not essential for biologically effective maternal behavior in laboratory rats, for pri-miparous females reared in isolation bear and rear young successfully (Sturman-Hulbe and Stone(l); Beach(2). Wiesner and Sheard (3) reported that female rats will display maternal behavior even though their young are removed by caesarean section, but this experiment lacked several necessary controls and there were no quantitative measures of the behavior. The present study was conducted to compare the maternal reactions of primiparous females that gave birth normally with those of females delivered by caesarean operation.
Methods. Twenty virgin female rats of the Sprague-Dawley strain were mated to males and placed in individual observation cages iy2 days before parturition was expected. The cages were 3 feet square and 2 feet deep, and 100 strips of paper toweling were suspended from the walls in such a way that the rat could easily detach them for use in nest building. Twenty-four hours after the animals were put in the cages, records were made of the number of paper strips detached and the grade of nests built. At this time 10 rats constituting the experimental group were subjected to caesarean operation and then returned with their young to the observation cages. Since the experimental rats did not lactate normally their young received little or no nourishment. Therefore, to make sure that these females would be stimulated by active babies during the retrieving test, each experimental animal was given a new, foster litter every 24 hours. The pregnant control rats remained in the cages and gave birth normally. Twenty-four hours after the young had been delivered, either surgically or naturally, the first retrieving test was conducted.
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