First year birds for which visual sexing according to plumage characteristics was not possible, were sexed using molecular tools. Genomic DNA was extracted from the cell fraction of each blood sample using a semi-automatic Maxwell kit method (Maxwell®16 LEV system Research, Promega, Madison, WI) which involves an enzymatic lysis using proteinase K followed by a purification of DNA using magnetic beads that bind to DNA . The sex identification test employs the primer pair CHD-P2 (5’ TCTGCATCGCTAAATCCTTT 3’) and CHD-P8 (5’ CTCCCAAGGATGAGRAAYTG 3’)  to amplify a CHD gene fragment. Each PCR reaction was performed with approximately 20 ng of genomic DNA as template using the following conditions: an initial denaturing step at 94°C for 2 min, 55°C for 30 s, 72°C for 1 min was followed by 34 cycles of 92°C for 30 s, 50°C for 30 s and 72°C for 45 s. A final run at 72°C for 5 min completed the program. The reaction products were checked by running in a 1.5% agarose gels for band visualization and sexing of each sample.