Scatter plot of systemic oxygen extraction fraction obtained from calves at 3 mo of age, according to survival status to 7 mo of age, and 7 mo of age. Measurements were taken at an altitude of 2,730 m. Calves presumed to have died before 7 mo of age are individually identified by a number. Median and quartiles are represented by dashed lines. Calves presumed dead by 7 mo of age tended to have greater systemic oxygen extraction fractions at 3 mo of age than calves that survived (P = 0.13).