Rates of growth and sexual maturation of Mongolian gerbils vary in response to photoperiod. Previous work has shown that the responses of the testes and body weight of juvenile and adult gerbils are influenced not only by the photoperiods but also by other factors. The present work sought to determine if Mongolian gerbils alter body mass, body composition and/or reproductive organ mass in response to different photoperiods and temperatures. Male Mongolian gerbils were raised under long (14L) or short (10L) photoperiods from 26 days of age. Photoperiods did not affect body mass and body length. Temperature affected body mass only under 10L with animals housed at 10ºC being significantly ligter than gerbils housed at 20ºC. Temperature did not affect the length of the body. Changes in body mass in response to photoperiod and/or temperature exposure were primarily due to the deposition or loss of fat-free dry mass and water. The mass of the reproductive organs (testes and seminal vesicles) was significantly decreased in gerbils housed under 10L. The mass of reproductive organs at 86 or 160 days of age was not affected by the temperature. Taken together, these results suggest that male Mongolian gerbils use photoperiodic information and temperature to change their body mass and reproductive organs.

Rates of growth and sexual maturation of Mongolian gerbils vary in response to photoperiod. Previous work has shown that the responses of the testes and body weight of juvenile and adult gerbils are influenced not only by the photoperiods but also by other factors. The present work sought to determine if Mongolian gerbils alter body mass, body composition and/or reproductive organ mass in response to different photoperiods and temperatures. Male Mongolian gerbils were raised under long (14L) or short (10L) photoperiods from 26 days of age. Photoperiods did not affect body mass and body length. Temperature affected body mass only under 10L with animals housed at 10ºC being significantly ligter than gerbils housed at 20ºC. Temperature did not affect the length of the body. Changes in body mass in response to photoperiod and/or temperature exposure were primarily due to the deposition or loss of fat-free dry mass and water. The mass of the reproductive organs (testes and seminal vesicles) was significantly decreased in gerbils housed under 10L. The mass of reproductive organs at 86 or 160 days of age was not affected by the temperature. Taken together, these results suggest that male Mongolian gerbils use photoperiodic information and temperature to change their body mass and reproductive organs.