Body weight and rumen-reticulum capacity in tule elk and mule deer

The relationship between body size and rumen-reticulum capacity among conspecific individuals is predicted to be isometric. We examined whether the relationship between body weight and rumen-reticulum capacity was isometric in adult male and female rule elk (Cervus elaphus nannodes) and in adult female mule deer (Odocoileus hemionus). We detected no effect of sex on this relationship in elk, and the slope of the regression was 1.0 for one measure of rumen-reticulum capacity and <1.0 for another. Among deer, the slope of the relationship was <1.0 in one measure of rumen-reticulum capacity, and we detected no relationship with the other.