At each farm, rams fitted with marking harnesses were
joined with ewes and ran as a single breeding group for
approximately 30 (May–July, studies 1 and 2) or 75 days
(August, study 3) beginning at CIDR removal. To detect
estrus at the first service period, ewes were observed for
the presence of raddle marks between 24 and 96 h after
ram introduction.