Abstract: For facilitation of conventional PCR technology to identify chicken sex, this study took the whole blood of adult chicks as a sample by the conventional PCR reaction mix and Tap DNA polymerase for direct PCR amplification, optimization was conducted in adult chicken whole blood (from 0.05 to 4.0 μL), Tap DNA polymerase (from 0.05 to 1.5 μL) and cycle number (from 30 to 40) in 50 μL direct PCR amplification system. Anti-coagulant selection and storage temperature of blood sample were evaluated, sex was identified with direct whole blood PCR amplification and compared with gonadal sex in 62 of 1-day-old chicklings, 80 of 12-day-old and 80 of 16-day-old chicken embryos, respectively. The results showed that sex identification with direct PCR amplification with 0.1 μL whole blood sample was fully consistent with the gonadal sex, therefore it was accuracy in chicklings and chicken embryos. ACD, heparin or DETA could be adopted as anticoagulant and blood samples could be stored at 4, －20 or －80 ℃ for 3 months at least. Compared with conventional PCR, the direct whole blood PCR could be economic, efficient and low possible of cross-contamination.

Key words: CHD1 gene; PCR amplification; whole blood; sex identification; chicken embryo; chicklings