Serum IGF-1 in pups and breeders. A. Serum IGF-1 concentrations in pups sacrificed at 35, 100, and 200 days of age. Bars and error bars represent means + SEM for each dietary group, N = 7–8 rats/group. For each time point, means not sharing a common superscript are significantly (p < 0.05) different using Fisher's or Tukey's pairwise comparisons. At each time point the main effects of Se (p < 0.0001, p = 0.022, and p = 0.003 at 35 days, 100 days, and 200 days, respectively) and of isoflavones (p = 0.019, p = 0.022, and p = 0.046 at 35 days, 100 days, and 200 days, respectively) were statistically significant. Interactions were statistically significant at 35 days (p = 0.004) and 200 days (p = 0.034). B. Serum IGF-1 concentrations in male breeders sacrificed at approximately 336 days of age. Neither isoflavones nor Se was significantly associated with serum IGF-1 levels in breeders.