Cows in drylot were in estrus longer (P < 0.04; 16.4 ± 0.8 h) than cows on pasture (14.2 ± 0.7 h). Duration of the longest interval between mounts received decreased (P < 0.002) as the number of cows in estrus at one time increased (5.3 ±0.7 h for 1 estrous cow; 2.6 ± 0.3 h when ≥7 cows were in estrus).