Lactating mice (Mus musculus) exhibit compensatory flexibility in gut morphology in response to reduced dietary protein

Abstract

Protein affects key life-history traits, and deficiencies in this nutrient may have selected for the ability to invoke physiological or morphological mechanisms to aid nutrient assimilation. I examined the effect of dietary protein on gut characters in lactating mice (Mus musculus L., 1758) and predicted that mice, to improve assimilation efficiency, would increase the mass of the stomach and small intestine and (or) increase food retention in these organs. Mice were maintained on isocaloric diets differing in protein and carbohydrate content (P:C) during the reproductive period. The hypothesis that food would be preferentially retained was not supported. However, both the stomach and the small intestine responded to low P:C with increased mass, and the small intestine exhibited increased diameter. This study demonstrates that mammalian gut morphology of lactating mice can respond to nutrient availability under conditions of constant energy intake. Further study is needed to determine if gut flexibility in response to decreasing P:C levels results in improved nitrogen assimilation efficiency and if this response is a general strategy of mammals or is limited to those with particular breeding strategies.