Effect of rams on the duration of oestrous behaviour in ewes.

rams once every 4 hr was shorter when ewes and rams remained together than when they were kept apart between observations. Continuous contact with rams appeared to limit the duration ofoestrus by inhibiting the neural mechanism controlling the expression of oestrous behaviour. Second, the duration of oestrus measured by teasing ewes individually every 4 hr and keeping them with rams between observations was longer than that measured when ewes were kept in continuous uncontrolled association with rams. Regular teasing probably resulted in a longer duration of oestrus because it eliminated competition between ewes and