Energy requirements during lactation in femaleApodemus chevrieri(Mammalia: Rodentia: Muridae) in the Hengduan Mountain region

Abstract

Lactation is the most energetically demanding period in small mammals. To investigate the energy balance strategies in lactating Apodemus chevrieri, we compared body mass, energy intake, thermogenic capacity, organ mass and other morphological parameters of the digestive tract of reproductive and non-reproductive females. The results showed that at parturition, mean body mass was 23.89% higher than that of the non-reproductive group. Over the course of the lactation period (from day 0 to day 21), females decreased by 24.30% in body mass and increased by 21.46% in resting metabolic rate (RMR), then all reached the original levels at day 30. Non-shivering thermogenesis (NST) decreased significantly and reached a minimum at peak lactation (on day 21). During lactation, mean NST was 18.55% lower than that of the non-reproductive group. At the same time, lactating A. chevrieri increased their energy intake significantly. Energy intake increased after parturition and reached a maximum at day 21 of lactation (216.46 kJ/day), 2.57 times that in the non-reproductive group, and then energy intake significantly decreased and reached the original level at day 30. Liver mass, digestive tract length and weight increased significantly in the lactating group compared to the non-reproductive group. All of the results indicated that A. chevrieri increased RMR and energy intake, decreased NST and body mass and mobilised the digestive tract to match the high energy demands for lactation.

Time and behavioral adjustments to lactation: Insights from a marine predator

“…This suggests that they are constrained to spend a similar proportional time diving regardless of the prey available. The observed behavior of L females is also similar to previously described patterns in other species, where the increased energetic demands of lactation are compensated by an increase of energy intake rather than changes in metabolic rate (Costa & Gentry, 1986;Costa & Trillmich, 1988;Harder et al, 1996;Oftedal et al, 1987;Zhu et al, 2015).…”

The Complex and Well-Developed Morphological and Histological Structures of the Gastrointestinal Tract of the Plateau Zokor Improve Its Digestive Adaptability to High-Fiber Foods

“…Certain morphological characteristics of the GIT may enable the digestion and absorption functions to match an animal’s energy needs in order for it to cope with its habitat environments [ 37 , 43 ]. The plateau zokors use high-fiber food resources and have a high energy-consuming lifestyle in the subterranean environments, and their GIT size and weight should therefore be larger than that of their aboveground counterparts, according to the view of Gross et al [ 5 ], Eto et al [ 34 ] and Langer and Clauss [ 24 ].…”

Mast seeding promotes evolution of scatter-hoarding

“…Half-saturation constant for mid-year reproduction ( h ) was set as 124 seeds/offspring multiplied by half the maximum number of female offspring ( b ). This value was calculated on the basis of energy contents of beech seeds (Grodziński and Sawicka-Kapusta 1970), energy requirements of yellow-necked mice (0.60 kcal/g/day: Jensen 1982; average body mass of yellow-necked mice is 28.3 g: AnAge), and typical costs of reproduction-related energy expenditure in small mammals (25% increase in energy expenditure during gestation and 200% increase during lactation: Millar 1978; 1979; Gittleman and Thompson 1988; Sikes 1995; Zhu et al 2015), given the length of gestation and lactation in yellow-necked mice (26 and 22 days, respectively: AnAge). Note that the link between food availability and reproduction limits winter breeding to masting events (which are known to result in winter reproduction in our and related study systems: Jensen 1982, Pucek et al 1993, Wolff 1996, Ostfeld et al 1996).…”