Gaskill, B., Garner, J. P., Pritchett-Corning, K. 2011. Energy reallocation to breeding performance through improved behavioral thermoregulation. American Association for Laboratory Animal Science [AALAS] Meeting Official Program, 771 (Abstract #P120).

Mice are housed at temperatures which increase their basal metabolic rates and impose high energy demands to maintain core temperatures. Thus, energy may be reallocated from other biologic processes to increase heat production. We hypothesized that nesting material will allow for behavioral thermoregulation by reducing heat loss. We predict this reduction will improve feed conversion as well as breeding performance. We housed naïve C57BL/6NCrl, BALB/cAnNCrl, and Crl:CD1(ICR) breeding pairs (30 cages per strain) at 20 °C with a nesting treatment: no additional material, 8 g of paper nesting material, or 8 g cotton fiber nesting material for 6 mo. Feed was weighed when added and at the end of the experiment, and fresh nesting material provided weekly. Pups were counted at birth and weighed and sexed at weaning. Analyses used GLM with post hoc contrasts. Nesting material improved feed efficiency per pup weaned (P = 0.02). However, there were no differences in the total feed consumed (P = 0.49). The breeding index (pups weaned per dam per week) was higher when either nesting materials were provided (P = 0.02). Thus, the energy conserved by nesting material was reallocated from heat generation to improved breeding performance.