Bioenergetics of pregnancy and lactation in the bank vole

Abstract

The food consumption and assimilation were determined in the females of bank vole, Clethrionomys glareolus (S c h r e b e r, 1780) during the whole period of pregnancy and lactation (18 + 18 days). The daily food assimilation (digestion) of non-reproducing females (body weight 25 g) isl 7.5 Kcal/animal. Toward the end of gestation it reaches 23.7 Kcal/day/animal and during the maximal lactation it averages 38.9 Kcal/day for the females of the same body weight. The energy requirement of females increases by 24% during the pregnancy and 92% during the lactation. To produce a litter of 5 young and raise 4 of them to weaning a female has to assimilate additionally 364 Kcal; 75 for the pregnancy and 289 Kcal for the lactation. The increase in food intake during this period corresponds to 406 Kcal. The digestibility coefficient is high in both non-reproducing and pregnant or lactating females (88.5%). The ecological efficiency is also very high; 11.8% during the pregnancy and 14.6% during the lactation. In the models of rodent bioenergetics the correction for gestation and lactation has to be considered. These corrections are computed for whole breeding season in relation to the number of mature females in the population.

Reproduction and mortality of bank voles and the changes in the size of an island population

“…The survival of mature females and that of immature ones, being different in the breeding season and similar in winter, seem therefore to be connected with their ability to reproduce and, first and foremost, with the reproductive functions of mature females and the decline of these functions in the winter season. Changes in metabolism may possibly be responsible for an increase in the survival of the mature females after the breeding season; participation in reproduction causes an increased expenditure of energy (Kaczmarski, 1966), and an increase in metabolism undoubtedly influences the survival of these females unfavourably.…”

Energy Allocation in Mammalian Reproduction

“…Mean caloric intake during lactation ranges from 66-188% greater than for non-reproductives {e.g., McC. Graham, 1964;Kaczmarski, 1966;Migula, 1969;Stebbins, 1977;Randolph et al 1977;Millar, 1978;Mattingly and McClure, 1982;Sadleir, 1982;Glazier, 1985«, b). These levels may vary directly with litter size {e.g., Smith and McManus, 1975;Millar, 1978;Sadleir, 1982) and may be over 200% in digestively inefficient species {e.g., the folivorous "carnivore," the red panda, Ailurus fulgens: Gittleman, 1988è; see also Studier, 1979).…”

“…For pregnant rodents, increase in mean daily caloric intake over non-reproductive rates ranges from 18-25% {e.g., Kaczmarski, 1966;Migula, 1969;Myrcha et al, 1969;Mattingly and McClure, 1982) and at least one of these species may store energy as fat for use during lactation {i.e., Sigmodon hispidus: Randolph et al, 1977; see also Mattingly and McClure, 1985). For most rodents, stored fat is not important for gestation.…”

Metabolism and energy budget in the snow vole

“…It was assumed that sex ratio in the population is 1:1 and 30% of females are reproducing. Since the rise of energy requirements of pregnant and lactating females amounts in common and bank voles to 70% on the average (Kaczmarski, 1966;Trojan & Wojciechowska, 1967; M i g u 1 a, 1969), the correction calculated for all the individuals in the population is equal to 10.5%. The two corrections amounting jointly to 24.9% can be added directly to the function expressing the relationship of ADMR and body weight.…”