| Abstract | dc.description.abstract | Lactation is the most energetically demanding period in the life
cycle of female mammals, and its effects on digestive flexibility
and the size of internal organs have been extensively studied in
laboratory mice and rats since the early 1900s. However, there
have been only two studies on this topic for wild rodent species.
Here, we analyzed digestive flexibility—that is, changes in gut
content, activity of digestive enzymes, and gut morphology—
during lactation in the caviomorph rodent Octodon degus. In
addition, we evaluated changes in the size of other internal organs
and analyzed their relationship with the resting metabolic rate.
We found that gut content, the dry masses of digestive chambers,
the dry mass of liver, and resting metabolic rate were greater in
lactating than in nonbreeding control females. In contrast, fat
stores were higher in control subjects. Maltase and aminopeptidase-
N specific activity did not change with lactation, and both
enzymes had greater activity values in the middle portion of the
small intestine. Thus, our data indicate that the previously reported
increase in food assimilation that occurs during lactation
in O. degus is related to a mass increase in several central organs,
leading, in turn, to higher energetic costs. Fat stores may help
to mitigate these costs, but, as expected for small animals, to a
limited extent. Our study reveals a complex interplay among
energy acquisition, storage, and expenditure processes that ultimately
determine an organism’s fitness. | en_US |
