Whitaker, J., Moy, S. S., Godfrey, V. et al. 2009. Effects of cage size and enrichment on reproductive performance and behavior in C57BL/6Tac mice. Lab Animal 38(1), 24-34.

While cage size did not affect reproductive performance, enrichment (regardless of cage size) did signficicantly benefit reproductive performance; pups from non-enriched cages weighed less and fewer survived to weaning age than pups from enriched cages.