Meeting Abstract

P3.46  Monday, Jan. 6 15:30  The Influence of Dietary Protein on Reproduction in Peromyscus californicus DERRICKSON, E.M.*; BRAZIER, L.; Loyola University Maryland, Baltimore; Loyola University Maryland, Baltimore ederrickson@loyola.edu

Mice of the genus Peromyscus, despite their many similarities, differ in body size, geographic range and reproductive characters. Larger members of the genus have smaller litters, slower growth, and more limited ranges, but the reason behind these changes in life history is not well understood. One possible correlate with a slower life history may be an inability to respond flexibly to changes in diet quality. The objective of this study is to determine whether species of Peromyscus that naturally have lower reproductive rates are less responsive to changes in dietary protein levels compared to species with higher reproductive rates. In the first stage of this study, our objectives were to determine (1) an “optimal” protein value in the diet in P. californicus and (2) the response curves to changing protein levels on pup production and growth, pup endurance, and maternal and pup body composition. Female P.californicus were placed on one of five isocaloric diets containing 6.9-23% protein and followed for three litters. Juveniles were tested for endurance when they reached 50% of adult mass. P. californicus exhibited a threshold type response to dietary protein with similar pup production and pup growth at all protein levels except the lowest. Optimal protein for pup growth occurred at 9%. Pup response, however, was plastic with pup endurance positively associated with maternal dietary protein. We are currently analyzing pup and maternal body composition patterns. This study provides a baseline in which to compare the response to dietary protein by Peromyscus that vary in body size and reproductive parameters.