After sperm cells were counted, the nuclei from 100,000 sperm were isolated with Lysis Buffer (10 mM Tris-HCl pH 7.4, 10 mM NaCl, 3mM MgCl2) containing 0.1% NP40, 0.1% Tween-20, and 0.01% Digitonin. Purified sperm nuclei pellet was then resuspended in the transposase reaction mix containing 0.05% digitonin and incubated for 30 min at 37°C. Following incubation, sperm were treated with Proteinase K at 55°C for 2 hr, and gDNA was isolated by phenol:chloroform:isoamyl alcohol and EtOH precipitation. Library amplification was done with 2x KAPA HiFi mix and 1.25 µM indexed primers using the following PCR conditions: 72°C for 5 min; 98°C for 30 s; and 10-11 cycles at 98°C for 10 s, 63°C for 30 s, and 72°C for 1 min.