Maternal Behavior and Emotional Status of Mother Rats at Different Stages of Lactation

The present study was conducted to investigate how the maternal behavior and emotional status of mothers in lactating rats alter with lactational stage.On day 3 and 12 of lactation, mothers were allowed to nurse their litters for 50min following 4h isolation and the behavioral responses during the nursing period were recorded.Latency to pup-retrieval and duration of retrieval behavior by mothers were significantly longer on day 3 than on day 12 of lactation, and the time that mothers spent on the nest with pups and the duration of licking by mothers increased significantly on day 12 as compared with day 3.The frequency of self-grooming and scratching behavior in mothers, an indirect index with which to evaluate emotional status, was significantly higher on day 3 of lactation than day 12.Moreover, the frequency of self-grooming showed a significant negative correlation with the time that mothers spent on the nest with pups and that mothers spent crouching over pups on day 3 of lactation, whereas there was no correlation between self-grooming behavior and pup-directed activities on day 12 of lactation.These results suggest that the attenuation of non pup-directed activities concerned with emotional status of mothers as well as the reinforcement of pup-directed activities is important for the establishment of lactational performance.