This article study on effects of different temperatures and storage time (group A:4℃ 0 day; group B:-70℃ 30 days; group C:4℃ 7 days) on blood DNA extracting from Chinese Holstein and comparison of three blood DNA extraction methods [reagent box method(E); improved reagent box method (F);phenol-chloroform method (G)].The results indicate:it had no significant effect on blood DNA extraction between group A and group B (P〉0.05);it bad significant effect on blood DNA extraction between group A and group C (P〈0.05),also between ...