Energy Acquisition and Allocation in Male Collared Lemmings (Dicrostonyx groenlandicus): Effects of Photoperiod, Temperature, and Diet Quality

Abstract

This study examined the effects of photoperiod (long photoperiod [LD, 20L:4D] and short photoperiod [SD, 8L:16D]), temperature (cold [C, 5° C] and warm [W, 18° C]), and diet quality (high-quality diet [HQ, 18% fiber] and low-quality diet [LQ, 49% fiber]) on growth, energy allocation, food intake, digestive efciency, and gut size in male collared lemmings (Dicrostonyx groenlandicus). Lemmings exposed to SD at weaning showed an increase in adult body mass relative to animals from the LD regimens and allocated twofold more energy to growth. Exposure to C increased adult body mass under LD but not SD. Adult body mass was reduced in lemmings fed the LQ diet relative to lemmings consuming the HQ diet. Lemmings exposed to SD tended to consume less food and showed a reduction in digestive efciency relative to lemmings exposed to LD even though gut size was relatively and absolutely larger under SD conditions. Lemmings acclimated to 5° C showed an increase in food intake and digestive efficiency relative to lemmings acclimated to 18° C The ability to increase digestive efficiency while increasing food intake at 5° C may have been due to the observed increases in the size of the small intestine, cecum, and large intestine. Similarly, the size of the gastrointestinal tract was larger in lemmings fed the LQ diet than in lemmings consuming the HQ diet. Use of fiber accounted for 32% of metabolizable energy (ME) in animals fed the LQ, but only 4% of the ME in those fed the HQ.