Long-Term Effect of Environmental Enrichment on Reproductive Performance of Swiss Webster Mice and Their Female Offspring

SIMPLE SUMMARY: The aim of this study was to evaluate the effect of the implementation of an environmental enrichment (EE) plan on reproductive performance in mice, applied during one year period in Swiss Webster breeders and their female offspring used as recipients for embryo transfer. Birth rate, litter size, pups’ weight at weaning, interlitter interval and time to first litter were compared against a control group that did not receive EE. In mice breeders, EE significantly increased pups’ weight compared to control group (p < 0.01), without changing any other reproductive parameters. In the offspring females used as recipients, EE did not modify reproductive parameters. Our results demonstrate that this enrichment plan, which is usually applied in mouse facilities for animal well-being, enhances pup’s weight at weaning, with no negative effects on the reproductive performance of Swiss Webster mice. ABSTRACT: The aim of this study was to evaluate the effect of an environmental enrichment (EE) plan on the reproductive performance of Swiss Webster mice and their female offspring used as recipients for embryo transfer. A total of 54 breeder mice and 60 F1 females, used as foster mothers, were allocated in two experimental groups to receive or not receive EE for physical well-being. Reproductive outcomes of the Swiss trios such as birth rate and pup number, litter size, pups’ weight at weaning, interlitter interval and time to first litter were analyzed. Environmental enrichment significantly increased pups weight from breeding trios compared to the control group (14.4 ± 0.1 vs. 13.8g ± 0.1, EE vs. control, respectively; p < 0.01). Other parameters did not differ between both groups. Reproductive parameters of female offspring used as recipients for embryo transfer did not differ among groups subjected or not to EE. These data demonstrate that the EE protocol applied in Swiss Webster breeder mice positively enhanced pups weight, and did not interfere with other reproductive outcomes. In conclusion, this study supports the implementation of EE plans usually applied for animal welfare in mouse facilities with slight improvement in reproductive performance.