Effects of Nesting Material on Energy Homeostasis in BALB/cAnNCrl, C57BL/6NCrl, and Crl:CD1(ICR) Mice Housed at 20 °C.

Discrepancies exist between the preferred temperature range for mice (26 to 32 °C) and current recommendations (20 to26 °C), which may alter metabolism and negatively affect studies using mice. Previous research indicates that nesting materialcan alleviate cold stress in mice; therefore, we sought to determine the effects of the amount of nesting material provided(0, 6, or 12 g) on heat energy loss and energy balance in 3 mouse strains housed at currently recommended temperatures duringthe daytime, a period of presumed inactivity. Groups of BALB/cAnNCrl, C57BL/6NCrl, and Crl:CD1(ICR) mice, balanced bystrain and sex, were group-housed and provided 0, 6, or 12 g of nesting material. After a 3-d acclimation period, body weightwas determined daily at 0800, food intake was determined at 0800 and 2000, and total heat production was evaluated from0800 to 2000 on 4 consecutive days and used to calculate energy balance and the respiratory quotient. Although the amount ofnesting material had no overall effect on food intake or heat production, mice provided 12 g of nesting material had greaterweight gain than those given 0 or 6 g. This increase in body weight might have been due to improved energy balance, whichwas corroborated by an increased respiratory quotient in mice provided 12 g of nesting material. In summary, although heatproduction did not differ, providing 12 g of nesting material improved energy balance, likely leading to an increase in bodyweight during the 0800-2000 testing period.