For phase 2 (daily collection for 14 d), sperm number decreased from d 1 to 5 and remained stable thereafter. During the intensive period (phase 2), there were 2.0 × 108 ± 0.1 sperm/mL and 2.1 × 1010 ± 0.1 sperm per ejaculate (means ± SEM). For phase 3 (collection twice/ week during 10 wk), there were 3.7 × 108 ± 0.1 sperm/ mL and 5.2 1010 ± 0.1 sperm per ejaculate (means ± SEM).