The cows were split into four groups: Group 1 (Double ovisynch): GnRH on day 0, PGF2 on day 7, and GnRH after 72hrs from PGF2?Group 2(Cidersynch): Cows of this group received CIDR + dose of GnRH on day o, CIDR was removed + injection dose PGF2 ?on day 35 after TAI, non-pregnant cows were administered, 2nd dose of PGF2?Group 3 (Resynch): GnRH on day 28 after AI, PGF2 ?injection.