Meeting Abstract

P2.101  Jan. 5  Low protein diets in lactating Mus musculus may increase protein assimilation DERRICKSON, EM*; MAREK, M; BRODRICK, J; Loyola College; Loyola College; Loyola College ederrickson@loyola.edu

Previous research has demonstrated that dietary protein levels lead to changes in milk protein levels in Mus musculus. Mice on a diet containing 10% protein produce milk that is 12% lower in protein content compared to females on an isocaloric 20% protein diet. The decline in milk protein is not linear with the decrease in dietary protein, indicating that females may compensate for this loss. Although females might maintain milk protein by utilizing body stores of protein, mass loss is minimal for females on low protein diets. Further, females do not compensate for low levels of dietary protein by increasing food consumption. We hypothesized that females may increase assimilation efficiency, which may be reflected in greater mass of tissues involved in assimilation. Female mice were placed on 10% or 20% isocaloric diets for 3 or 28 days. Female mass, small intestine length, wet and dry mass of organs of the digestive tract, and wet mass of heart, kidneys, gonads, and liver were measured. Significantly greater stomach wet and dry mass, liver mass, and colon dry mass were seen by day 3 for females receiving the 10% diet. We also investigated whether transit time decreased on the low protein diet. Total transit time did not differ by diet treatment and averaged 204 minutes. Initial movement through the small intestine also was measured in lactating and non-lactating females. Although reproductive status affected the length of the small intestine, neither diet nor reproductive status affected the speed that a marker traveled. These results support the hypothesis that mice increase assimilation efficiency in response to low protein levels by increasing the surface area for absorption, and not by increasing the amount of time that food is processed.