Enrichment materials do not negatively affect reproductive success and offspring survival and weight in mice

Environmental enrichment is designed to improve the overall welfare of laboratory animals, including mice. Few studies have directly assessed the effects of different types of enrichment on mouse offspring survival and growth. The authors examined how survival and growth of C57BL/6 mouse pups are affected by three kinds of cage enrichment materials: compressed cotton squares, two-ply tissues and plastic igloos. During the last week of gestation and the first two weeks postpartum, the authors observed cages with litters and noted use of the enrichment materials, quality of nest construction, number of pups per litter and weight of pups. Both the first and second litters were evaluated for each dam. Dams and pups had continuous contact with the enrichment materials, especially cotton squares and tissues. Neither the presence nor the type of enrichment material influenced the survival and weight of offspring, suggesting that the use of such materials does not negatively impact reproductive success or offspring survival.