| Popis: |
A mathematical model for energy requirements of individual, non-reproducing and reproducing female small rodents is developed. Employing data on the metabolism of the common vole Microtus arvalis during reproduction, the parameters are estimated by least square techniques. In all measurements applied the temperature was held constant at 20'C. The "best" mathematical representation of the data is found by analysis of variance and error-term analysis. The models so found are concluded to represent the data without systematic deviations. The analysis indicates, however, that some predictive variable other than weight, number of days from conception, and number in each litter is needed to predict the metabolic rate more accurately. Such identification represents an important bioenergetic field of study. The deductions of precise mathematical functions representing the data facilitate a detailed analysis of how metabolic rates depend on weight of mother, time in reproductive period, and number of young per litter. The conclusions reached are: (1) During gestation total metabolic rate is not increased greatly relative to non-reproductive state; (2) The increased total energetic cost due to pregnancy decreases with increasing initial weight of mother; (3) An initial drop in total metabolic rate during the first 1/3 of pregnancy is observed; (4) During lactation a marked increase in metabolic rate is seen, although no marked change occurs just at the time of parturition. These conclusions are compared with earlier statements in literature. Survival of fetuses and sucklings is discussed on the basis of the bioenergetic cost due to reproduction: This indicates that energy might be a limiting resource for demographic features such as survival. |
